Search

Introduction: Transseptal puncture (TSP) is routinely performed for left atrial ablation procedures. The use of a three-dimensional (3D) mapping system or intracardiac echocardiography (ICE) is useful in localizing the fossa ovalis and reducing fluoroscopy use. We aimed to compare the safety and efficacy between 3D mapping system-guided TSP and ICE-guided TSP techniques., Methods: We conducted a prospective observational study of patients undergoing TSP for left atrial catheter ablation procedures (mostly atrial fibrillation ablation). Propensity scoring was used to match patients undergoing 3D-guided TSP with patients undergoing ICE-guided TSP. Logistic regression was used to compare the clinical data, procedural data, fluoroscopy time, success rate, and complications between the groups., Results: Sixty-five patients underwent 3D-guided TSP, and 151 propensity score-matched patients underwent ICE-guided TSP. The TSP success rate was 100% in both the 3D-guided and ICE-guided groups. Median needle time was 4.00 min (interquartile range [IQR]: 2.57-5.08) in patients with 3D-guided TSP compared to 4.02 min (IQR: 2.83-6.95) in those with ICE-guided TSP (p = .22). Mean fluoroscopy time was 0.2 min (IQR: 0.1-0.4) in patients with 3D-guided TSP compared to 1.2 min (IQR: 0.7-2.2) in those with ICE-guided TSP (p < .001). There were no complications related to TSP in both group., Conclusions: Three-dimensional mapping-guided TSP is as safe and effective as ICE-guided TSP without additional cost., (© 2022 The Authors. Journal of Cardiovascular Electrophysiology published by Wiley Periodicals LLC.)

Introduction: Monitored anesthesia care (MAC) or general anesthesia (GA) can be used during catheter ablation (CA) of atrial fibrillation (AF). However, each approach may have advantages and disadvantages with variability in operator preferences. The optimal approach has not been well established. The purpose of this study was to compare procedural efficacy, safety, clinical outcomes, and cost of CA for AF performed with MAC versus GA., Methods: The study population consisted of 810 consecutive patients (mean age: 63 ± 10 years, paroxysmal AF: 48%) who underwent a first CA for AF. All patients completed a preprocedural evaluation by the anesthesiologists. Among the 810 patients, MAC was used in 534 (66%) and GA in 276 (34%). Ten patients (1.5%) had to convert to GA during the CA., Results: Although the total anesthesia care was longer with GA particularly in patients with persistent AF, CA was shorter by 5 min with GA than MAC (p < 0.01). Prevalence of perioperative complications was similar between the two groups (4% vs. 4%, p = 0.89). There was no atrioesophageal fistula with either approach. GA was associated with a small, ~7% increase in total charges due to longer anesthesia care. During 43 ± 17 months of follow-up after a single ablation procedure, 271/534 patients (51%) in the MAC and 129/276 (47%) patients in the GA groups were in sinus rhythm without concomitant antiarrhythmic drug therapy (p = 0.28)., Conclusion: With the participation of an anesthesiologist, and proper preoperative assessment, CA of AF using GA or MAC has similar efficacy and safety., (© 2022 The Authors. Journal of Cardiovascular Electrophysiology published by Wiley Periodicals LLC.)

Purpose: We aim to describe the long-term safety and efficacy of catheter ablation (CA) in young patients (<30 years) with atrial fibrillation (AF)., Methods: This was a retrospective study of patients aged 18-30 who underwent CA for AF, and clinical characteristics and long-term outcomes are reported. Survival analyses were performed between the study group and a propensity-matched older cohort (>30 years, mean age: 58±10 years)., Results: From January 2000 to January 2019, a 1st CA (radiofrequency energy n=72, cryoballoon n=10), was performed in 82 patients (mean age 26±4 years, paroxysmal n=61, persistent n=14, longstanding persistent n=7), among 6336 consecutive patients with AF. During a follow-up of 5±5 years, 56% and 30% of the patients with paroxysmal and non-paroxysmal AF were arrhythmia free without antiarrhythmic drug (AAD) therapy after a single CA (P=0.02). After 1.5±0.8 CA procedures, 76% and 75% of the patients with paroxysmal AF and non-paroxysmal AF were arrhythmia free without AADs (P=0.54). Compared to a propensity-matched group of older patients, young patients were as likely to remain in sinus rhythm after CA (P=0.47), however after fewer repeat CAs (1.5±0.8 vs 1.9±0.9, P<0.009). There were no long-term adverse outcomes associated with CA., Conclusions: CA is a safe and effective treatment of AF in young patients with comparable outcomes to the older patients, however after fewer procedures., (© 2021. Springer Science+Business Media, LLC, part of Springer Nature.)

Background: Diabetes mellitus (DM) is a risk factor for atrial fibrillation (AF). The effect of antidiabetic medications on AF or the outcomes of catheter ablation (CA) has not been well described. We sought to determine whether metformin treatment is associated with a lower risk of atrial arrhythmias after CA in patients with DM and AF., Methods and Results: A first CA was performed in 271 consecutive patients with DM and AF (age: 65 ± 9 years, women: 34%; and paroxysmal AF: 51%). At a median of 13 months after CA (interquartile range: 6-30), 100/182 patients (55%) treated with metformin remained in sinus rhythm without antiarrhythmic drug therapy, compared with 36/89 patients (40%) not receiving metformin (p = .03). There was a significant association between metformin therapy and freedom from recurrent atrial arrhythmias after CA in multivariable Cox hazards models (hazard ratio [HR]: 0.66; ±95% confidence interval [CI]: 0.44-0.98; p = .04) that adjusted for age, sex, body mass index, AF type (paroxysmal vs. nonparoxysmal), antiarrhythmic medication, obstructive sleep apnea, chronic kidney disease, coronary artery disease, left ventricular ejection fraction, and left atrial diameter. A Cox model that also incorporated other antidiabetic agents and fasting blood glucose demonstrated a similar reduction in the risk of recurrent atrial arrhythmias with metformin treatment (HR: 0.63; ±95% CI: 0.42-0.96; p = .03)., Conclusions: In patients with DM, treatment with metformin appears to be independently associated with a significant reduction in the risk of recurrent atrial arrhythmias after CA for AF. Whether this effect is due to glycemic control or pleiotropic effects on electroanatomical mechanisms of AF remains to be determined., (© 2021 Wiley Periodicals LLC.)

Background: It is not clear if antiarrhythmic drug therapy (AAD) after catheter ablation (CA) of atrial fibrillation (AF) increases mortality., Objective: To determine whether there is an association between AAD therapy and mortality after CA of AF., Methods: There were 3624 consecutive patients with AF (mean age: 59 ± 11 years, women: 27%, paroxysmal AF: 58%). An AAD was used in 2253 patients (62%, AAD group) for a mean duration of 1.3 ± 0.8 years, during a mean follow-up of 6.7 ± 2.2 years after CA of AF. Using propensity score matching, with every 2 patients using an AAD matched to 1 patient who did not use AAD (NO-AAD group), Cox regression models were utilized to assess the association between AAD use (as a time-variable covariate) and all-cause mortality., Results: There were a total of 50 deaths (2.2%) in the AAD and 62 deaths (4.5%) in the NO-AAD groups, respectively (P = .02). At the time of death, 46 of 50 patients (92%) who died in the AAD cohort were still using an AAD (P = .21, compared to baseline use). On multivariate analysis, although the risk of death was not statistically significant between the AAD and NO-AAD cohorts, there was a trend towards mortality benefit with AAD therapy (hazard ratio [HR]: 0.66, 95% confidence interval [CI]: 0.43-1.00, P = .05), regardless of the rhythm or anticoagulation status., Conclusion: AAD use after CA of AF is not associated with an increased risk of mortality, suggesting that when carefully chosen and monitored, AADs appear to be safe after CA of AF., (Copyright © 2019 Heart Rhythm Society. All rights reserved.)

Background: The role of cryoballoon ablation (CBA) for antral pulmonary vein isolation (APVI) has not been well established in persistent atrial fibrillation (PerAF). Isolation of the left atrial posterior wall (BOX) after APVI has been suggested to improve the efficacy of radiofrequency catheter ablation (RFA) in PerAF., Objective: The purpose of this study was to compare characteristics and clinical outcomes of APVI by CBA vs APVI + BOX by contact force-guided RFA (CF-RFA) in patients with PerAF., Methods: APVI was performed in 167 consecutive patients with PerAF (mean age 64 ± 9 years; left atrial diameter 46 ± 6 mm) using CBA (n = 90) or CF-RFA (n = 77). After APVI, a roofline was created in 33 of 90 patients (37%) in the CBA group and BOX was performed in all 77 patients in the CF-RFA group., Results: During 21 ± 10 months of follow-up after a single ablation procedure, 37 of 90 patients (41%) in the CBA group (APVI) and 39 of 77 (51%) in the CF-RFA group (APVI + BOX) remained in sinus rhythm without antiarrhythmic drugs (AADs) (P = .22). During repeat ablation, APVI + BOX using CF-RFA was performed in 20 of 90 patients (22%) and in 18 of 77 patients (23%) who initially underwent CBA or CF-RFA, respectively. At 19 ± 10 months after repeat ablation, sinus rhythm was maintained in 55 of 90 patients (61%) and 52 of 77 patients (68%) in the CBA and CF-RFA groups without AADs, respectively (P = .39)., Conclusion: In PerAF, an initial approach of APVI by CBA or APVI + BOX by CF-RFA has a similar efficacy of 40%-50% without AADs. After repeat ablation for APVI + BOX by CF-RFA in ∼25%, sinus rhythm is maintained in 60%-70% of patients without AADs., (Copyright © 2018 Heart Rhythm Society. All rights reserved.)

Purpose: The endpoint for radiofrequency catheter ablation (RFA) of cavo-tricuspid isthmus (CTI)-dependent atrial flutter (AFL) is complete conduction block along the CTI. The purpose of this study is to evaluate the utility of the temporal relationship between the P wave and the local atrial electrograms in determining complete CTI block., Methods: RFA of CTI was performed in 125 patients (age 63 ± 11 years). During pacing from the coronary sinus (CS), the intervals from the peak of the P wave (P peak ) in lead V 1 to the second component of the local atrial electrogram (A 2 ) along the ablation line (P peak -A 2 ) and from the end of the P wave (P end ) to A 2 (P end -A 2 ) were investigated before and after complete block in the first 100 patients (training set). In the next 25 patients (validation set), P peak -A 2 and P end -A 2 intervals were prospectively assessed to determine CTI block., Results: The mean P peak -A 2 and P end -A 2 immediately before complete block were - 15±24 and - 39±23 ms compared to 49 ± 17 and 21 ± 16 ms after CTI block (P < 0.0001). P peak -A 2 ≥ 20 ms and P end -A 2 ≥ 0 ms predicted CTI block with 98% sensitivity and 95% specificity and 96% sensitivity and 100% specificity, respectively. In the validation set, the positive and negative predictive values of P peak -A 2 ≥ 20 ms or P end -A 2 ≥ 0 ms were 100 and 96%, respectively. The diagnostic accuracy was 98%., Conclusions: During pacing from the CS, the temporal relationship between the P wave in lead V 1 and A 2 is a simple and reliable indicator of complete block during RFA of CTI-AFL.

Background: There are no randomized controlled studies of the efficacy and safety of protamine to reverse anticoagulant effects of heparin after catheter ablation (CA) of atrial fibrillation (AF)., Objective: The purpose of this study was to determine the efficacy and safety of protamine to expedite vascular hemostasis and ambulation after CA of AF., Methods: CA to eliminate AF (n = 139) or left atrial flutter (n = 11) was performed in 150 patients using radiofrequency catheter ablation (n = 112) or cryoballoon ablation (n = 38). CA was performed under uninterrupted anticoagulation with warfarin in 28 patients or after skipping a single dose of a novel oral anticoagulant in 122 patients who were randomized to receive protamine (n = 77) or to the control group (n = 73). Baseline and procedural characteristics were similar between the 2 groups. Hemostasis was achieved manually once the activated clotting time returned to preprocedural values., Results: The maximum activated clotting time during CA was 359 ± 31 and 359 ± 29 seconds in the protamine and control groups, respectively (P = .91). The time to hemostasis was 123 ± 95 minutes in the protamine group and 260 ± 70 minutes in the control group (P < .001). The time to ambulation was 316 ± 80 and 480 ± 92 minutes in the protamine and control groups, respectively (P < .001). There were no differences in the rates of major or minor vascular access complications or thromboembolic events (P > .05)., Conclusion: Protamine expedites vascular hemostasis and time to ambulation by ∼3 hours after CA of AF without an increase in the risk of vascular or thromboembolic complications., (Copyright © 2018 Heart Rhythm Society. All rights reserved.)

Introduction: Although noninferiority of cryoballoon ablation (CBA) and radiofrequency catheter ablation for antral pulmonary vein isolation (APVI) has been reported in patients with paroxysmal atrial fibrillation (PAF), it is not clear whether contact force sensing (CF-RFA) and CBA with the second-generation catheter have similar procedural costs and long-term outcomes. The objective of this study is to compare the long-term efficacy and cost implications of CBA and CF-RFA in patients with PAF., Methods and Results: A first APVI was performed in 146 consecutive patients (age: 63 ± 10 years, men: 95 [65%], left atrial diameter: 42 ± 6 mm) with PAF using CBA (71) or CF-RFA (75). Clinical outcomes and procedural costs were compared. The mean procedure time was significantly shorter with CBA than with CF-RFA (98 ± 39 vs. 158 ± 47 minutes, P < 0.0001). Despite a higher equipment cost in the CBA than the CF-RFA group, the total procedure cost was similar between the two groups (P = 0.26), primarily driven by a shorter procedure duration that resulted in a lower anesthesia cost. At 25 ± 5 months after a single ablation procedure, 51 patients (72%) in the CBA, and 55 patients (73%) in the CF-RFA groups remained free from atrial arrhythmias without antiarrhythmic drug therapy (P = 0.84)., Conclusions: The procedure duration was approximately 60 minutes shorter with CBA than CF-RFA. The procedural costs were similar with both approaches. At 2 years after a single procedure, CBA and CF-RFA have similar single-procedure efficacies of 72-73%., (© 2017 Wiley Periodicals, Inc.)

Background: Frequent premature ventricular complexes (PVCs) have been associated with increased mortality. However, the optimal approach to the risk stratification of these patients is unclear., Objective: The purpose of this study was to prospectively assess the use of cardiac magnetic resonance imaging (MRI) and programmed ventricular stimulation to identify patients with PVCs undergoing radiofrequency ablation at risk for adverse long-term outcomes., Methods: A total of 321 consecutive patients (52 ± 15 years; 157 men [49%]; left ventricular ejection fraction 51% ± 12%) underwent PVC ablation between 2004 and 2015, preceded by cardiac MRI to assess for structural heart disease (SHD). Programmed stimulation was performed at the time of the ablation procedure. If ventricular tachycardia (VT) was induced in the presence of SHD, an implantable cardioverter-defibrillator (ICD) was implanted., Results: SHD was identified by MRI in 64 patients (20%), and sustained monomorphic VT was inducible in 15 patients (5%). Fourteen patients had both SHD and inducible VT, and received an ICD after the procedure. The primary endpoint of VT/ventricular fibrillation or death was met in 15 patients after a median 20 months of follow-up. The combination of SHD by MRI and VT inducibility conferred independently an increased risk of adverse outcome (multivariate hazard ratio 25.73, 95% confidence interval 6.74-98.20; P <.001)., Conclusion: Preablation cardiac MRI and programmed stimulation can be useful for risk stratification in patients with frequent PVCs. Patients with inducible VT in the setting of SHD may benefit from ICD implantation after ablation regardless of left ventricular ejection fraction., (Copyright © 2017 Heart Rhythm Society. All rights reserved.)

Background: Frequent idiopathic premature ventricular complexes (PVCs) can result in PVC-induced cardiomyopathy. Frequent PVCs can also aggravate ischemic cardiomyopathy., Objective: The purpose of this study was to investigate the impact of frequent PVCs on nonischemic cardiomyopathy., Methods: This was a consecutive series of 30 patients (mean age 59.1 ± 12.1; 18 men; mean ejection fraction [EF] 38% ± 15%) with structurally abnormal hearts based on the presence of scar on cardiac magnetic resonance imaging and/or a history of cardiomyopathy before the presence of frequent PVCs who were referred for ablation of frequent PVCs., Results: Ablation was successful in 18 of 30 patients (60%), resulting in an increase of mean EF from 33.9% ± 14.5% to 45.7% ± 17% (P < .0001) during mean follow-up of 30 ± 28 months. The PVC burden in these patients was reduced from 23.1% ± 8.8% to 1.0% ± 0.9% (P < .0001). Mean EF did not change in patients with a failed ablation procedure (44.4 ± 16 vs 43.5 ± 21, P = .85). The PVC site of origin was in scar tissue in 14 of 18 patients with a successful ablation procedure. Mean New York Heart Association functional class improved from 2.3 ± 0.6 to 1.1 ± 0.2 (P < .0001) in patients with a successful outcome and remained unchanged in patients with an unsuccessful outcome (1.9 ± 0.9 vs 1.9 ± 0.7, P = 1)., Conclusion: In patients with frequent PVCs and nonischemic cardiomyopathy, EF and functional class can be improved but not always normalized by successful PVC ablation. In most patients with an effective ablation, the arrhythmogenic substrate was located in scar tissue., (Copyright © 2015 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Atrial fibrillation (AF) is associated with a significant increase in the risk of stroke and mortality. It is unclear whether maintaining sinus rhythm (SR) after radiofrequency ablation (RFA) is associated with an improvement in stroke risk and survival., Objective: The purpose of this study was to determine whether SR after RFA of AF is associated with an improvement in the risk of cerebrovascular events (CVEs) and mortality during an extended 10-year follow-up., Methods: RFA was performed in 3058 patients (age 58 ± 10 years) with paroxysmal (n = 1888) or persistent AF (n = 1170). The effects of time-dependent rhythm status on CVEs and cardiac and all-cause mortality were assessed using multivariable Cox models adjusted for baseline and time-dependent variables during 11,347 patient-years of follow-up., Results: Independent predictors of a higher arrhythmia burden after RFA were age (estimated beta coefficient [β] = 0.017 per 10 years, 95% confidence interval [CI] 0.006-0.029, P = .003), left atrial (LA) diameter (β = 0.044 per 5-mm increase in LA diameter, 95% CI 0.034-0.055, P <.0001), and persistent AF (β = 0.174, 95% CI 0.147-0.201, P <.0001). CVEs and cardiac and all-cause mortality occurred in 71 (2.3%), 33 (1.1%), and 111 (3.6%), respectively. SR after RFA was associated with a significantly lower risk of cardiac mortality (hazard ratio [HR] 0.41, 95% CI 0.20-0.84, P = .015). There was not a significant reduction in all-cause mortality (HR 0.86, 95% CI 0.58-1.29, P = .48) or CVEs (HR 0.79, 95% CI 0.48-1.29, P = .34) in patients who remained in SR after RFA., Conclusion: Maintenance of SR after RFA is associated with a reduction in cardiovascular mortality in patients with AF., (Copyright © 2014 Heart Rhythm Society. All rights reserved.)

Background: The prevalence and clinical consequences of coronary arterial injury in a large series of patients undergoing radiofrequency ablation (RFA) of atrial fibrillation (AF) are unknown., Objective: The purpose of this study was to describe the frequency and clinical consequences of coronary arterial injury in a large series of patients undergoing catheter ablation of AF and postablation atrial tachycardia., Methods: The medical records of 5,709 consecutive patients undergoing RFA of AF were reviewed. Heart specimens were also dissected to analyze the course of the coronary arteries., Results: Arterial injury occurred in 8 patients (0.14%). Three patients developed ventricular fibrillation (VF) due to occlusion of the distal or proximal circumflex (Cx) artery related to RFA in the distal coronary sinus (CS) or base of the LA appendage, respectively. Two VF patients underwent stenting. Five patients developed acute sinus node (SN) dysfunction. In 4/5 patients, the culprit site was subjacent to the SN artery (per computed tomography) coursing over the anterior LA (n = 3) or the septal RA (n = 1). Two patients required a permanent pacemaker. In the heart specimens, the SN artery, after its origin from the proximal Cx artery, coursed along the anterior LA. Also, the proximal Cx artery was found in the atrioventricular groove underneath the base of the LA appendage., Conclusion: Clinically apparent injury to the coronary arteries during LA ablation for AF is rare. However, it may be associated with potentially life-threatening ventricular arrhythmias and acute SN dysfunction requiring permanent pacing. The culprit sites seem to be in the distal coronary sinus and the anterior LA, and correlate well with the course of the coronary arteries in pathologic specimens. Vigilance and low-power settings are important in minimizing the risk of arterial injury., (© 2013 Heart Rhythm Society. All rights reserved.)

Background: Ventricular arrhythmias have been described to originate from intramural locations. Intramural scar can be assessed by delayed-enhanced MRI, but MRIs cannot be performed on every patient. The objective of this study was to assess the value of voltage mapping to detect MRI-defined intramural scar and to correlate the scar with ventricular arrhythmias., Methods and Results: In 15 consecutive patients (3 women; age 55±16 years; ejection fraction, 49±13%) with structural heart disease, intramural scar was detected by delayed-enhanced MRI. All patients underwent endocardial unipolar and bipolar voltage mapping guided by the registered intramural scar. Scar volume by MRI was 11.7±8 cm3 with a scar thickness of 4.6±0.7 mm and a preserved endocardial/epicardial rim of 3.3±1.6 and 4.8±2.6 mm, respectively. Endocardial bipolar voltage was 1.6±1.73 mV at the scar, 2.12±2.15 mV in a 1 cm perimeter around the scar, and 2.83±3.39 mV in remote myocardium without scar. The corresponding unipolar voltage was 4.94±3.25, 6.59±3.81, and 8.32±3.39 mV, respectively (P<0.0001). Using receiver-operator characteristic curves, a unipolar cut-off value of 6.78 mV (area under the curve, 0.78) and a bipolar cut-off value of 1.55 mV (area under the curve, 0.69) best separated endocardial measurements overlying scar as compared with areas not overlying a scar. At least 1 intramural ventricular arrhythmia was eliminated in all but 2 patients in this series., Conclusions: Intramural scar can be detected by unipolar and bipolar voltage, unipolar voltage being more useful. Mapping and ablation of intramural arrhythmias originating from an intramural focus can be accomplished.

Background: The right ventricular outflow tract (RVOT) is the most common site of origin of ventricular arrhythmias (VAs) in patients with idiopathic VAs. A left bundle branch block, inferior axis morphology arrhythmia is the hallmark of RVOT arrhythmias. VAs from other sites of origin can mimic RVOT VAs, and ablation in the RVOT typically fails for these VAs., Objective: To analyze reasons for failed ablations of RVOT-like VAs., Methods: Among a consecutive series of 197 patients with an RVOT-like electrocardiographic (ECG) morphology who were referred for ablation, 38 patients (13 men; age 46 ± 14 years; left ventricular ejection fraction 47% ± 14%) in whom a prior procedure failed within the RVOT underwent a second ablation procedure. ECG characteristics of the VA were compared to a consecutive series of 50 patients with RVOT VAs., Results: The origin of the VA was identified in 95% of the patients. In 28 of 38 (74%) patients, the arrhythmia origin was not in the RVOT. The VA originated from intramural sites (n = 8, 21%), the pulmonary arteries (n = 7, 18%), the aortic cusps (n = 6, 16%), and the epicardium (n = 5, 13%). The origin was within the RVOT in 10 (26%) patients. In 2 (5%) patients, the origin could not be identified despite biventricular, aortic, and epicardial mapping. The VA was eliminated in 34 of 38 (89%) patients with repeat procedures. The ECG features of patients with failed RVOT-like arrhythmias were different from the characteristics of RVOT arrhythmias., Conclusions: In patients in whom ablation of a VA with an RVOT-like appearance fails, mapping of the pulmonary artery, the aortic cusps, the epicardium, the left ventricular outflow tract, and the aortic cusps will help identify the correct site of origin. The 12-lead ECG is helpful in differentiating these VAs from RVOT VAs., (Copyright © 2013 Heart Rhythm Society. All rights reserved.)

Background: Most infarct-related ventricular tachycardias (VTs) have an exit site that can be targeted by endocardial ablation. However, some VT reentry circuits have an exit site that is intramural or epicardial. Even these circuits may have an endocardial component that can be endocardially ablated., Objective: To assess the prevalence of postinfarction VTs with a nonendocardial exit site that can be successfully eliminated by endocardial ablation., Methods: Twenty-eight consecutive patients with postinfarction VT (27 men, age 69 ± 8 years, ejection fraction 0.25% ± 0.15%) were referred for VT ablation. A total of 213 VTs were inducible (cycle length 378 ± 100 ms). Pace mapping was performed throughout the scar, and critical sites were identified for 137 VTs (64.5%). Critical sites identified by entrainment mapping and/or pace mapping were divided into exit and nonexit sites depending on the stimulus-QRS/VT cycle length ratio (S-QRS/VT CL ≤ 0.3 vs>0.3)., Results: Endocardial exit sites (S-QRS/VTCL ≤ 0.3) were identified for 100 of 137 VTs. Only critical nonexit sites were identified for 37 of 137 (27%) VTs. Nonexit sites were confined to a smaller area within the endocardium (1.81 ± 1.7 cm(2)) and were located within dense scar (0.28 ± 0.24 mV) further away from the border zone (2.05 ± 2.79 cm) than did the VT exit sites. Exit sites had a larger area of matching pace maps (3.86 ± 1.9 cm(2); P<.01) and were at a closer distance to the border zone (0.93 ± 1.06 cm; P<.01). A total of 133 of 137 VTs were ablated. The success rate was similar for VTs in which exit sites were targeted (n = 90 of 100) and VTs in which only nonexit sites were targeted (n = 36 of 37) (P = .83)., Conclusions: In about one-third of postinfarction VTs for which critical sites were identified, the exit site was not endocardial. Critical nonexit sites that are effective for ablation are often within dense scar at a distance from the border zone and can be missed if only the border zone is targeted., (Copyright © 2013 Heart Rhythm Society. All rights reserved.)

Background: It is not clear whether dabigatran is as safe and effective as uninterrupted anticoagulation with warfarin during radiofrequency catheter ablation (RFA) of atrial fibrillation (AF)., Objective: To compare the safety and efficacy of dabigatran by using a novel administration protocol and uninterrupted anticoagulation with warfarin for periprocedural anticoagulation in patients undergoing RFA of AF., Methods: In this case-control analysis, 763 consecutive patients (mean age 61±10 years) underwent RFA of AF using dabigatran (N = 191) or uninterrupted warfarin (N = 572) for periprocedural anticoagulation. In all patients, anticoagulation was started≥4 weeks before RFA. Dabigatran was held after the morning dose on the day before the procedure and resumed 4 hours after vascular hemostasis was achieved., Results: A transesophageal echocardiogram performed in all patients receiving dabigatran did not demonstrate an intracardiac thrombus. There were no thromboembolic complications in either group. The prevalence of major (4 of 191, 2.1%) and minor (5 of 191, 2.6%) bleeding complications in the dabigatran group were similar to those in the warfarin group (12 of 572, 2.1%; P = 1.0 and 19 of 572, 3.3%; P = .8, respectively). Pericardial tamponade occurred in 2 of 191 (1%) patients in the dabigatran group and in 7 of 572 (1.2%) patients in the warfarin group (P = 1.0). All patients who had a pericardial tamponade, including 2 in the dabigatran group, had uneventful recovery after perdicardiocentesis. On multivariate analysis, international normalized ratio (odds ratio [OR] 4.0; 95% confidence interval [CI] 1.1-15.0; P = .04), clopidogrel use (OR 4.2; 95% CI 1.5-12.3; P = .01), and CHA2DS2-VASc score (OR 1.4; 95% CI 1.1-1.8; P = .01) were the independent risk factors of bleeding complications only in the warfarin group., Conclusions: When held for approximately 24 hours before the procedure and resumed 4 hours after vascular hemostasis, dabigatran appears to be as safe and effective as uninterrupted warfarin for periprocedural anticoagulation in patients undergoing RFA of AF., (Copyright © 2013 Heart Rhythm Society. All rights reserved.)

Background: While macroreentrant atrial tachycardias (ATs) have been reasonably well described, little is known about small reentrant circuits., Objective: To compare characteristics of large and small reentrant circuits after ablation of persistent atrial fibrillation., Methods: Seventy-seven patients (age 61±10 years; left atrium 46±6 mm; ejection fraction 0.52±0.13) underwent a procedure for postablation AT. The p-wave duration, circuit size, electrogram characteristics, and conduction velocity were determined., Results: AT was due to macroreentry in 62 (80%) patients, a small reentrant circuit in 13 (17%), and a focal mechanism in 2 (3%). The p-wave duration during small reentrant ATs was shorter than that during macroreentry (174±12 ms vs 226±22 ms; P<.0001). The duration of fractionated electrograms at the critical site was longer in small vs large circuits (167±43 ms vs 98±38 ms, respectively; P<.0001) and accounted for a greater percentage of the tachycardia cycle length (59%±18% vs 38%±14%, respectively; P<.0001). The mean diameters of macroreentrant and small reentrant circuits were 44±7 and 26±11 mm, respectively (P<.0001). The mean conduction velocity along the small circuits was lower (0.5±0.2 m/s vs 1.2±0.3 m/s; P<.0001). Catheter ablation eliminated the AT in all 77 patients., Conclusions: AT due to a small reentrant circuit after ablation of atrial fibrillation may be distinguished from macroreentry by a shorter p-wave duration and the presence of long-duration electrograms at the critical site owing to extremely slow conduction. These features may aid the clinician in the mapping of postablation ATs., (Copyright © 2013 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Patients with frequent premature ventricular complexes (PVCs) and PVC-induced cardiomyopathy usually have recovery of left ventricular (LV) dysfunction postablation. The time course of recovery of LV function has not been described., Objective: To describe the time course and predictors of recovery from LV dysfunction after effective ablation of PVCs in patients with PVC-induced cardiomyopathy., Methods: In a consecutive series of 264 patients with frequent idiopathic PVCs referred for PVC ablation, LV dysfunction was present in 87 patients (mean ejection fraction 40%±10%). The PVC burden was reduced to<20% of the initial PVC burden in 75 patients. In these patients, echocardiography was repeated 3-4 months postablation. If LV function did not normalize after 3-4 months, a repeat echocardiogram was performed every 3 months until there was normalization or stabilization of LV function., Results: The ejection fraction normalized at a mean of 5±6 months postablation. The majority of patients (51 of 75, 68%) with PVC-induced LV dysfunction had a recovery of LV function within 4 months. In 24 (32%) patients, recovery of LV function took more than 4 months (mean 12±9 months; range 5-45 months). An epicardial origin of PVCs was more often present (13 of 24, 54%) in patients with delayed recovery of LV function than in patients with early recovery of LV function (2 of 51, 4%; P<.0001). The PVC-QRS width was significantly longer in patients with delayed recovery than in patients with recovery within 4 months (170±21 ms vs 159±16 ms; P = .02). In multivariate analysis, only an epicardial PVC origin was predictive of delayed recovery of LV function in patients with PVC-induced cardiomyopathy., Conclusions: PVC-induced cardiomyopathy resolves within 4 months of successful ablation in most patients. In about one-third of the patients, recovery is delayed and can take up to 45 months. An epicardial origin predicts delayed recovery of LV function., (Copyright © 2013 Heart Rhythm Society. All rights reserved.)

Background: Advancing age is a strong risk factor for the development of atrial fibrillation (AF). However, its impact on the left atrial (LA) substrate in patients is not well defined., Methods: Forty-seven patients underwent catheter ablation of persistent AF. Bipolar electrograms from the LA were recorded for voltage analysis. The AF cycle length was determined by averaging the cycle lengths of ten fibrillatory ("f") waves on lead V(1). The mean amplitude of the same ten "f" waves was also determined. The ablation strategy consisted of pulmonary vein isolation, electrogram guided, and linear ablation., Results: There was an inverse relationship between the mean bipolar LA voltage and age (R = -0.58; P < 0.0001). There was a direct relationship between AF cycle length and age (R = 0.74; P < 0.0001). There was an inverse relationship between amplitude of the "f" waves and age (R = -0.62; P < 0.0001). Areas of scar were found in 15 of the 47 patients (32%). AF cycle length was longer in patients with vs. those without scar (183 ± 20 vs. 151 ± 15 ms; P < 0.0001). Advancing age was the only predictor of LA scar (OR, 1.32; 95% CI, 1.11-1.58; P < 0.01). Forty patients (85%) remain arrhythmia-free without antiarrhythmic medications after a mean follow-up of 18 ± 10 months. Neither age nor LA scar was associated with outcome., Conclusions: In patients undergoing ablation of persistent AF, advancing age makes for a complex LA substrate that is characterized by areas of low voltage/scar, and yet is associated with a lower AF frequency. LA scar did not seem to impact outcome in this small study.

Purpose: This study aims to determine the impact of preprocedural imaging using computerized tomography (CT) or magnetic resonance imaging (MRI) with 3-D reconstruction on procedural efficiency, efficacy, complications and clinical outcome in patients who undergo radiofrequency catheter ablation (RFA) to eliminate atrial fibrillation (AF)., Methods: In this registry, a CT (n = 161) or MRI (n = 37) was obtained prior to RFA in 198 of 333 consecutive patients (age 61 ± 10 years) with paroxysmal (172) or persistent (161) AF. Antral pulmonary vein isolation was performed in all patients using an open-irrigation-tip catheter with a 3-D electroanatomical navigation system. Procedural and clinical outcomes were compared among patients who underwent RFA with and without preprocedural imaging., Results: The mean duration of the procedure (246 ± 47 vs. 242 ± 40 min, P = 0.55), fluoroscopy (47 ± 13 vs. 50 ± 10 min, P = 0.16), and total RF application (83 ± 27 vs. 78 ± 23 min, P = 0.17) were similar among patients who did and did not have preprocedural imaging. The likelihood of a complication also was similar (5/198 [3%] vs. 4/135 [3%], P = 1.0). A repeat ablation was performed in 95/198 (48%) and 61/135 (45%) of the patients who did and did not have imaging study, respectively (P = 0.62). At 22 ± 9 months, after a mean of 2 ± 1 procedures, 140/198 (71%) and 101/135 (75%) of the patients who did and did not have preprocedural imaging were in sinus rhythm (P = 0.4)., Conclusions: Preprocedural awareness of pulmonary venous and left atrial anatomy does not appear to have an effect on procedural efficiency or clinical outcomes in patients who undergo catheter ablation for AF.

Background: Intramural septal idiopathic ventricular arrhythmias have not been described systematically., Methods and Results: In a consecutive group of 93 patients with idiopathic ventricular arrhythmias referred for ablation, the site of origin of ventricular arrhythmias was assessed by activation mapping and pace-mapping. In 7 of 93 patients (8%), an intramural focus in the interventricular septum was identified. All ventricular arrhythmias arising intramurally had a left bundle-branch block morphology with inferior axis. The intramural focus was effectively ablated from both sides of the septum in 4 patients and from within the septum in 1 patient. The ablation procedure of an intramural focus near the His bundle failed in 2 of 7 patients. ECG and mapping characteristics of the patients with intramural septal ventricular arrhythmias differentiated intramural arrhythmias from other sites of origin., Conclusions: Idiopathic septal ventricular arrhythmias can originate from intramural foci. Activation mapping from within a perforator branch within the interventricular septum is helpful in identifying the site of origin of intramural septal arrhythmias. Ablation within the septum or from both sites of the septum may be required to eliminate the targeted arrhythmia.

Post-infarction arrhythmias are most often confined to scar tissue. Scar can be detected by delayed-enhanced cardiac magnetic resonance. The purpose of this study was to assess the feasibility of pre-procedural scar identification and intraprocedural real-time image registration with an electroanatomical map in 23 patients with previous infarction and ventricular arrhythmias (VAs). Registration accuracy and cardiac magnetic resonance/electroanatomical map correlations were assessed, and critical areas for VA were correlated with the presence of scar. With a positional registration error of 3.8 ± 0.8 mm, 86% of low-voltage points of the electroanatomical map projected onto the registered scar. The delayed-enhanced cardiac magnetic resonance-defined scar correlated with the area of low voltage (R = 0.82, p < 0.001). All sites critical to VAs projected on the registered scar. Selective identification and extraction of delayed-enhanced cardiac magnetic resonance defined scar followed by registration into a real-time mapping system are feasible and help to identify and display the arrhythmogenic substrate in post-infarction patients with VAs., (Copyright © 2012 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: Frequent idiopathic premature ventricular complexes (PVCs) can result in a reversible form of cardiomyopathy. In this study, the determinants of PVC-induced left ventricular (LV) dysfunction were assessed., Methods: The subjects of this study were 241 consecutive patients (115 men [48%], mean age 48 ± 14 years) referred for ablation of frequent PVCs. One hundred eighty patients (75%) experienced palpitations and 61 (25%) did not. The PVC burden was determined by 24-hour Holter monitoring, and echocardiograms were performed to assess LV function. An LV ejection fraction of <50% was considered abnormal., Results: LV ejection fraction (mean 0.36 ± 0.09) was present in 76 of 241 patients (32%). There was a higher prevalence of males among the patients with PVC cardiomyopathy compared to patients with normal LV function (51/76 [67%] vs 64/165 [39%]; P <.0001). The mean PVC burden was significantly higher in patients with PVC cardiomyopathy than in patients with normal LV function (28% ± 12% vs 15% ± 13%; P <.0001). Among symptomatic patients, those with cardiomyopathy had a significantly longer duration of palpitations (135 ± 118 months) compared with patients with normal LV function (35 ± 52 months; P <.0001). The proportion of asymptomatic patients was significantly higher in the presence of cardiomyopathy (36/76, 47%) than in normal LV function (25/165, 15%; P <.0001). Symptom duration of 30 to 60 months, symptom duration >60 months, the absence of symptoms, and the PVC burden in asymptomatic patients were independent predictors of impaired LV function (adjusted odds ratio [95% confidence interval]: 4.0 [1.1-14.4], 20.1 [6.3-64.1], 13.1 [4.1-37.8], and 2.1 [1.2-3.6], respectively)., Conclusions: The duration of palpitations and the absence of symptoms are independently associated with PVC-induced cardiomyopathy., (Copyright © 2012 Heart Rhythm Society. All rights reserved.)

Introduction: Factors associated with cerebrovascular events (CVEs) after radiofrequency catheter ablation (RFA) of atrial fibrillation (AF) have not been well defined in elderly patients (≥65 years). The purpose of this study was to determine the prevalence and predictors of CVEs after RFA in patients with AF ≥65 years old, in comparison to patients <65 years, and with or without AF., Methods and Results: This study included 508 consecutive patients ≥65 years old (mean age: 70 ± 4 years), who underwent RFA for paroxysmal (297) or persistent (211) AF. A stratified group of 508 patients < 65 years old who underwent RFA for AF served as a control group. All patients were anticoagulated with warfarin for ≥3 months after RFA. A perioperative CVE (≤4 weeks after RFA) occurred in 0.8% and 1% of patients ≥65 and <65 years old, respectively (P = 1). Among the patients ≥65 years old who remained in sinus rhythm after RFA, warfarin was discontinued in 60% and 56% of the patients with a CHADS(2) score of 0 and ≥1, respectively. Paroxysmal AF, no history of CVE, and successful RFA were independent predictors of discontinuing warfarin. During a mean follow-up of 3 ± 2 years, a late CVE (>4 weeks after the RFA) occurred in 15 of 508 (3%) of patients ≥65 years old (1% per year) and in 5 of 508 (1%) patients <65 years old (0.3% per year, P = 0.03). Among patients ≥65 years old, age >75 years old (OR = 4.9, ±95% CI: 3.3-148.5, P = 0.001) was the only independent predictor of a CVE. Among patients <65 years old, body mass index was the only independent predictor of a late CVE (OR = 1.2, ±95% CI: 1.03-1.33, P = 0.02)., Conclusions: The risk of a periprocedural CVE after RFA of AF is similar among patients ≥65 and <65 years old. Late CVEs after RFA are more prevalent in older than younger patients with AF, and age >75 years old is the only independent predictor of late CVEs regardless of the rhythm, anticoagulation status, or the CHADS(2) score (Congestive heart failure, Hypertension, Age ≥ 75 years, Diabetes mellitus and prior Stroke or transient ischemic attack)., (© 2011 Wiley Periodicals, Inc.)

Objective: The objective was to determine the effect of radiofrequency catheter ablation (RFA) on progression of paroxysmal atrial fibrillation (AF)., Background: Progression to persistent AF may occur in up to 50% of patients with paroxysmal AF receiving pharmacological therapy. Hypertension, age, prior transient ischemic event, chronic obstructive pulmonary disease, and heart failure (HATCH score) have been identified as independent risk factors for progression of AF., Methods: RFA was performed in 504 patients (mean age: 58 ± 10 years) to eliminate paroxysmal AF. A repeat RFA procedure was performed in 193 patients (38%). Clinical variables predictive of outcome and their relation to progression of AF after RFA were assessed using multivariate analysis., Results: At a mean follow-up of 27 ± 12 months after RFA, 434/504 patients (86%) were in sinus rhythm; 49/504 patients (9.5%) continued to have paroxysmal AF; and 14 (3%) were in atrial flutter. Among the 504 patients, 7 (1.5%) progressed to persistent AF. In patients with recurrent AF after RFA, paroxysmal AF progressed to persistent AF in 7/56 (13%, P < 0.001). The progression rate of AF was 0.6% per year after RFA (P < 0.001 compared to 9% per year reported in pharmacologically treated patients). Age >75 years, duration of AF >10 years and diabetes were independent predictors of progression to persistent AF. The HATCH score was not significantly different between patients with paroxysmal AF who did and did not progress to persistent AF (0.7 ± 0.8 vs 1.0 ± 0.5, P = 0.3)., Conclusions: Compared to a historical control group of pharmacologically treated patients with paroxysmal AF, RFA appears to reduce the rate of progression of paroxysmal AF to persistent AF. Age, duration of AF, and diabetes are independent risk factors for progression to persistent AF after RFA., (© 2011 Wiley Periodicals, Inc.)

Objectives: The purpose of this study was to assess the prevalence of the re-entry circuit within the interventricular septum in post-infarction patients referred for ventricular tachycardia (VT) ablation., Background: Post-infarction ventricular tachycardia can involve the endocardial myocardium, the intramural myocardium, the epicardium, or the His Purkinje system., Methods: Among 74 consecutive patients with recurrent post-infarction VT, 33 patients (45%) were identified in whom the critical part of the VT involved the interventricular septum. A total of 206 VTs were induced in these 33 patients. In 46 of the 206 VTs, a critical component was identified in the interventricular septum. The critical isthmus of the re-entry circuit was identified by entrainment mapping, activation mapping, or pace-mapping., Results: In 32 of 46 VTs (70%), the critical component of the re-entry circuit was confined to the endocardium. In 9 of 46 VTs (20%), the critical component involved the Purkinje system, and in 5 of 46 VTs (11%), an intramural area was critical. Entrainment and/or pace-mapping helped to identify critical areas of endocardial VTs as well as VTs involving the Purkinje fibers, but neither of these mapping techniques localized intramural VTs. Electrocardiographic characteristics were specific for each of the septal locations. All VTs mapped to the interventricular septum were acutely successfully ablated. VTs recurred in 9 of 33 patients with septal VTs during a mean follow-up period of 40 ± 20 months., Conclusions: Post-infarction VT involving the interventricular septum can involve the endocardial muscle, Purkinje fibers, or intramural muscle fibers. Electrocardiographic characteristics differ depending on the type of tissue involved., (Copyright © 2011 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: Idiopathic epicardial ventricular arrhythmias can be targeted from the coronary venous system or the pericardial space, the endocardium, or the aortic sinus cusps., Objective: The purpose of this study was to analyze systematically the contribution of ablation at sites other than the epicardium to eliminate an arrhythmia originating in the epicardium., Methods: In a consecutive patient series of 33 patients (14 women, age 51 ± 14 years, ejection fraction 51% ± 9%) with epicardial ventricular arrhythmias, mapping and ablation was performed via the cardiac venous system/pericardial space, the aortic sinus cusp, and the left ventricular endocardium. An arrhythmia was defined as epicardial if the earliest onset of activation and a matching pace-map (≥10/12 leads) were identified in the epicardium., Results: In 12/33 patients (36%), either an endocardial approach alone (n = 3) or a combined endocardial/epicardial (n = 6), cusp/endocardial (n = 1), or cusp/epicardial (n = 2) approach was required to eliminate the ventricular arrhythmias. In 10 of 33 patients (30%), epicardial ablation alone was effective in eliminating epicardial ventricular arrhythmias. Ablation was ineffective due to failure to reach the site of origin with the ablation catheter in 5 of 33 patients (15%), the site of origin was too close to an epicardial artery or the phrenic nerve in 3 patients (6%), and power delivery was insufficient in 3 patients (9%)., Conclusion: About one-third of epicardial arrhythmias require ablation from sites other than the epicardium to eliminate the arrhythmia focus., (Copyright © 2011 Heart Rhythm Society. All rights reserved.)

Background: Large-tip (10 mm) catheters (LTCs) and open-irrigation-tip catheters (OITCs), both capable of creating large lesions, are more effective than conventional catheters for cavotricuspid isthmus (CTI) ablation. However, it is not clear whether complete CTI block can be achieved more efficiently using an LTC or an OITC. The purpose of this study was to compare the efficiency of radiofrequency catheter ablation (RFA) of the CTI using LTC versus OITC to eliminate atrial flutter (AFL)., Methods and Results: Sixty consecutive patients (age = 62 ± 10 years) with typical AFL were randomized to undergo RFA of CTI using an LTC (10 mm) or an OITC. If complete CTI block was not achieved by ≤30 minutes of RFA, patients were allowed to cross over to ablation with the other catheter. A 3-dimensional electroanatomical mapping system was used for catheter navigation only with the OITC. The mean duration of RFA to achieve CTI block in 50% of the patients was 6.8 ± 2.2 minutes with an LTC and 11.7 ± 2.7 minutes with an OITC (P = 0.001). After 30 minutes of RFA, CTI block was achieved in 26/30 (87%) and 25/30 patients (83%) using an LTC and an OITC, respectively (P = 1.0). After crossover, CTI block was achieved in 4/5 (80%) and in 4/4 patients (100%) with an LTC and OITC, respectively (P = 1.0). LTC was associated with a lower volume of intravenous fluid administration (388 ± 365 mL versus 865 ± 451 mL, P = 0.0001) and a trend for shorter procedure duration (95 ± 31 minutes versus 114 ± 50 minutes, P = 0.09) than the OITC. At 6 ± 3 months, 30/30 patients (100%) in the LTC and 27/30 patients (90%) in the OITC groups remained free from AFL, respectively (P = 0.24). Except for one inconsequential steam-pop during RFA with the OITC, there were no complications., Conclusions: Complete CTI block is achieved more rapidly using an LTC than an OITC, and with a similar clinical efficacy. , (© 2011 Wiley Periodicals, Inc.)

Introduction: Up to 6% of patients experience complications after radiofrequency catheter ablation (RFA) of atrial fibrillation (AF). The purpose of this study is to determine the prevalence and predictors of periprocedural complications after RFA for AF., Methods and Results: The subjects were 1,295 consecutive patients (age = 60 ± 10 years) who underwent RFA (n = 1,642) for paroxysmal (53%) or persistent AF (47%) from January 2007 to January 2010. A complication occurred in 57 patients (3.5%); a vascular access complication in 31 (1.9%); pericardial tamponade in 20 (1.2%); a thromboembolic event in 4 (0.2%); deep venous thrombosis in 1 (<0.01%); and pulmonary vein stenosis in 1 patient (<0.01%). There were no procedure-related deaths. On multivariate analysis, female gender (OR = 2.27; ±95% CI: 1.31-2.57, P < 0.01) and procedures performed in July or August (OR = 2.10; ±95% CI: 1.16-3.80, P = 0.01) were independent predictors of any complication. For vascular complications, treatment with clopidogrel (OR = 4.40; ±95% CI: 1.43-13.53, P = 0.01), female gender (OR = 3.65; ±95% CI: 1.72-7.75, P < 0.01) and performing RFA in July or August (OR = 2.71; ±95% CI: 1.25-5.87, P = 0.01) were independent predictors. The only predictor of cardiac tamponade was prior RFA (OR = 3.32; ±95% CI: 0.95-11.61; P < 0.05)., Conclusion: Prevalence of perioperative complications for RFA of AF is 3.5% and vascular access complications constitute the majority. The need for clopidogrel therapy should be carefully considered prior to RFA. At teaching institutions close supervision should be exercised during vascular access early in the year. Improvements in ablation technology and elimination of the need for repeat procedures may decrease the risk of pericardial tamponade., (© 2011 Wiley Periodicals, Inc.)

Background: Structural factors contributing to the development of postinfarction ventricular tachycardia (VT) are unclear. The purpose of this study was to analyze infarct architecture and electrogram characteristics in patients with and without inducible VT and to identify correlates of postinfarction VT., Methods and Results: Twenty-four postinfarction patients (median age, 64 [53, 70] years) were referred for radiofrequency catheter ablation of VT (n = 12) or frequent symptomatic premature ventricular contractions (PVCs) (n = 12). Delayed-enhanced (DE) MRI was obtained before ablation. Electroanatomical mapping was performed and scar area and electrogram characteristics of the scar tissue compared in patients with and without inducible VT. The median ejection fraction in patients with and without inducible VT was 27% (22%, 43%) and 43% (40%, 47%), respectively (P = 0.085). Subendocardial infarct area determined by DE-MRI was larger in patients with inducible VT (43 [38, 62] cm(2)) than in those with noninducible VT (8 [4, 11] cm(2); P = 0.002), and unipolar and bipolar voltages on electroanatomical maps were significantly lower in patients with inducible VT (both P<0.05). An infarct volume of >14% identified 11 of 12 patients with inducible VT (area under the curve, 0.94; P = 0.007). On electroanatomical mapping, distinct sites with isolated potentials (IPs) were more prevalent in patients with inducible VT than in those without (13.2% versus 1.1% of points within scar; P < 0.001). The number of inducible VTs correlated with the number of distinct sites with IPs (R = 0.87; P<0.0001)., Conclusions: Scar tissue in postinfarction patients with inducible VT shows quantitative and qualitative differences from scars in patients without inducible VT. Scar size and IPs are correlated with VT inducibility.

Background: Ablation of arrhythmias arising from the papillary muscles (PAPs) is challenging., Objective: The purpose of this study was to assess the predictors of successful catheter ablation in patients with ventricular arrhythmias arising from the PAPs., Methods: Forty consecutive patients (15 women, mean age 51 ± 14 years, left ventricular ejection fraction 0.46 ± 0.13) with refractory PAP arrhythmias underwent mapping and ablation. Catheter stability was assessed with intracardiac echocardiography. Activation mapping and/or pace mapping were performed to identify the site of origin. Electrophysiological data and anatomic characteristics were assessed in patients with effective versus ineffective ablation. Catheter stability was assessed with intracardiac echocardiography., Results: Radiofrequency ablation was acutely effective in eliminating the targeted arrhythmia in 31 patients (78%). The presence of Purkinje potentials at the site of origin of the targeted arrhythmia was associated with an effective outcome (48% vs. 0%; P = .01). The mass of the arrhythmogenic PAPs in the left ventricle was significantly larger in patients with failed versus effective ablation (4.7 ± 2.2 g vs. 2.3 ± 0.6 g; P < .0001). Also, the presence of a matching pace map at the earliest endocardial activation time was associated with an effective procedure (71% vs. 22%; P = .02), Conclusion: The presence of Purkinje potentials at the site of origin and a smaller size of the PAP are associated with successful ablation of PAP arrhythmias., (Copyright © 2010 Heart Rhythm Society. All rights reserved.)

Introduction: Premature ventricular complexes (PVCs) occur frequently in patients with heart disease. The sites of origin of PVCs in patients with prior myocardial infarction and the response to catheter ablation have not been systematically assessed., Methods and Results: In 28 consecutive patients (24 men, age 60 ± 10, ejection fraction [EF] 0.37 ± 0.14) with remote myocardial infarction referred for catheter ablation of symptomatic refractory PVCs, the PVCs were mapped by activation mapping or pace mapping using an irrigated-tip catheter in conjunction with an electroanatomic mapping system. The site of origin (SOO) was classified as being within low-voltage (scar) tissue (amplitude ≤1.5 mV) or tissue with preserved voltage (>1.5 mV). The SOO was confined to endocardial scar tissue in 24/28 patients (86%). The SOO was outside of scar in 3 patients and could not be identified in 1 patient. At the SOO, local endocardial activation preceded the PVC by 46 ± 19 ms, and the electrogram amplitude during sinus rhythm was 0.48 ± 0.34 mV. The PVCs were effectively ablated in 25/28 patients (89%), resulting in a decrease in PVC burden on a 24-hour Holter monitor from 15.6 ± 12.3% to 2.4 ± 4.2% (P < 0.001). The SOO most often was confined to scar tissue located in the left ventricular septum and the papillary muscles., Conclusion: Similar to post-infarction ventricular tachycardia, PVCs after remote myocardial infarction most often originate within scar tissue. Catheter ablation of these PVCs has a high-success rate., (© 2010 Wiley Periodicals, Inc.)

Background: In patients with prior infarction, isolated potentials (IPs) during sinus rhythm reflect fixed scar and often indicate sites critical for ventricular tachycardia (VT). The purpose of this study was to determine the value of IPs in conjunction with pace-mapping to guide VT ablation in patients with various types of nonischemic cardiomyopathy., Methods: Mapping and ablation of VT were performed in 35 consecutive patients (26 men, age 55 ± 13 years, ejection fraction 0.31 ± 0.14) with VT and various etiologies of nonischemic cardiomyopathy. Pace-mapping was performed at sites with low voltage. Radiofrequency energy was delivered at sites with concealed entrainment or matching pace-maps., Results: One hundred ninety-five VTs (mean cycle length 363 ± 88 ms) were induced. Sites with prespecified ablation criteria displaying IPs during sinus rhythm were recorded in 21 of 35 patients (60%, IP-positive). In these patients, a total of 216 sites meeting prespecified ablation criteria were identified and 146 of 216 sites (68%) displayed IPs. Fifteen of 21 IP-positive patients (71%) no longer had inducible VT after ablation. In 14 of 35 patients, no sites with IPs where prespecified ablation criteria were met were identified (IP-negative) despite combined endocardial and epicardial mapping in 7 of 14 patients. Only 1 of 14 IP-negative patients (7%) no longer had inducible VT at the end of the ablation procedure. During a mean follow-up of 18 ± 13 months, 14 of 21 IP-positive patients (67%) remained arrhythmia-free, compared to 1 of 14 IP-negative patients (7%; P < 0.01). Half of the IP-negative patients had major adverse events due to recurrent arrhythmias, compared to none in IP-positive patients., Conclusion: IPs in conjunction with pace-mapping are helpful for identifying critical isthmus areas for ablation of VT in patients with various types of nonischemic cardiomyopathy. Patients with nonischemic cardiomyopathy in whom the arrhythmogenic substrate is characterized by IPs have a more favorable outcome than patients in whom IPs are absent., (© 2010 Wiley Periodicals, Inc.)

Background: The prevalence of epicardial idiopathic ventricular arrhythmias that can be ablated from within the coronary venous system (CVS) has not been described., Methods and Results: In a consecutive group of 189 patients with idiopathic ventricular arrhythmias referred for ablation, the site of origin (SOO) of ventricular tachycardia and/or premature ventricular contractions was determined by activation mapping and pace mapping. Mapping was performed within the CVS if endocardial mapping did not reveal an SOO. Venography of the CVS and coronary angiography were performed before ablation in the CVS. In 27 of 189 patients (14%+/-5%; 95% confidence interval), the SOO of the ventricular arrhythmia was identified from within the coronary venous system, either in the great cardiac vein (n=26) or the middle cardiac vein (n=1). The mean activation time at the SOO was -29+/-8 ms. Twenty of 27 patients (74%) underwent successful ablation within the CVS. Epicardial ventricular arrhythmias displayed a broader R wave in V(1) compared with arrhythmias in the control group (85 ms [interquartile range, 40] versus 65 ms [interquartile range, 95]; P<0.01). Two patients had recurrent premature ventricular contractions within 2 weeks after ablation, and no recurrences occurred in the remaining patients during a median follow-up of 13 months (range, 25). In the 7 patients with unsuccessful ablation, failure was because the ablation catheter could not be advanced to the SOO within the great cardiac vein (n=4), inadequate power delivery at the SOO (n=1), proximity to the phrenic nerve (n=1), or proximity of the SOO to a major coronary artery (n=1). Transcutaneous epicardial ablation was effective in 1 of 2 patients in whom it was attempted., Conclusions: Almost 15% of idiopathic ventricular arrhythmias have an epicardial origin. ECG characteristics help to differentiate epicardial arrhythmias from endocardial ventricular arrhythmias. The SOO of epicardial arrhythmias can be ablated from within the CVS in approximately 70% of patients.

Background: Premature ventricular complexes (PVCs) and ventricular tachycardia (VT) with origin in the left ventricular papillary muscle have recently been described. There are no prior studies describing the characteristics of the ventricular arrhythmias (VAs) arising from the right ventricular papillary muscles (RV PAPs)., Methods: Among 169 consecutive patients who underwent a catheter ablation of a VA, eight patients with RV PAPs were identified (seven men, mean PVC burden 17.0% +/- 20%). A control group consisted of 10 consecutive patients with arrhythmias originating from the right ventricle (10 women, mean PVC burden 13.9% +/- 12.8%). All patients underwent cardiac magnetic resonance imaging (MRI). Intracardiac echocardiography was used to identify the site of origin of the RV PAP arrhythmias. The site of origin of a total of 15 distinct PAP arrhythmias was mapped to the following papillary muscles: posterior (n = 3), anterior (n = 4), or septal (n = 8)., Results: Postablation echocardiograms did not reveal new tricuspid regurgitation. During a mean follow-up of 8 +/- 9 months, there were no adverse outcomes. The PVC burden was reduced from 17% +/- 20% preablation to 0.6% +/- 0.8% postablation in the RV PAP group and from 13.9% +/- 12.8% to 0.3% +/- 0.4% in the control group. The QRS complex was broader in the RV PAP group compared with in the control group (163 +/- 21 ms vs. 141 +/- 22 ms; P = .02). RV PAP arrhythmias originating from the posterior or anterior RV PAPs more often had a superior axis with late R-wave transition (>V4) compared with septal RV RAP arrhythmias, which more often had an inferior axis with an earlier R-wave transition in the precordial leads (

Objectives: To identify and characterize ablation lesions after radiofrequency (RF) catheter ablation of ventricular arrhythmias in patients without prior myocardial infarction and to correlate the ablation lesions with the amount of RF energy delivered and the clinical outcome., Background: Visualization of RF energy lesions after ablation of ventricular arrhythmias might help to identify reasons for ablation failure., Methods: In a consecutive series of 35 patients (19 women, age: 48 +/- 15 years, ejection fraction: 0.56 +/- 0.12) without structural heart disease who were referred for ablation of ventricular arrhythmias, cardiac magnetic resonance imaging with delayed enhancement was performed before and after ablation. Ablation lesions were sought in the post-ablation cardiac magnetic resonance images. The endocardial area, depth, and volume of the lesions were measured. Lesion size was correlated with the type of ablation catheter used and the duration of RF energy delivered., Results: In 25 of 35 patients (71%), ablation lesions were identified by delayed enhancement a mean of 22 +/- 12 months after the initial ablation procedure. The mean lesion volume was 1.4 +/- 1.4 cm(3), with a mean endocardial area of 3.5 +/- 3.0 cm(2). The largest lesions (mean volume of 2.9 +/- 2.1 cm(3) with an endocardial area of 6.4 +/- 3.4 cm(2)) were identified in patients in whom the arrhythmias originated in the papillary muscles. Ablation duration correlated with lesion size (r = 0.67, p < 0.001). There was no difference in lesion volume with irrigated versus nonirrigated ablation catheters (1.0 +/- 0.73 vs. 2.0 +/- 2.1 cm(3), p = 0.09). Identification of ablation lesions in patients with a failed procedure identified the sites where ineffective RF energy lesions were created., Conclusions: RF ablation lesions can be detected long term after an ablation procedure targeting ventricular arrhythmias in patients without previous infarction. Lesion size correlates with the amount of RF energy delivered and is largest when a targeted arrhythmia originates in a papillary muscle., (Copyright 2010 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: Termination of persistent atrial fibrillation (AF) by radiofrequency ablation (RFA) is associated with a high probability of freedom from AF but requires extensive ablation and long procedure times., Objective: The purpose of this study was to determine whether a critical decrease in the dominant frequency (DF) of AF is a sufficient endpoint for RFA of persistent AF., Methods: Antral pulmonary vein isolation (APVI) followed by RFA of complex fractionated atrial electrograms (CFAEs) in the atria and coronary sinus was performed in 100 consecutive patients with persistent AF. The DF of AF in lead V1 and in the coronary sinus was determined by fast Fourier transform (FFT) analysis at baseline and before termination of AF to identify a critical decrease in DF predictive of sinus rhythm after RFA., Results: A > or =11% decrease in DF had the highest accuracy in predicting freedom from atrial arrhythmias, with a sensitivity of 0.71 and a specificity of 0.82 (P <.001). At a mean follow-up of 14 +/- 3 months after one ablation procedure, sinus rhythm was maintained off antiarrhythmic drugs in 8/35 (23%) and 20/26 (77%) of patients with a <11% and > or =11% decrease in DF, respectively (P <.001). Sinus rhythm was maintained in 24/39 patients (62%) in whom RFA terminated AF. The duration of RFA and total procedure time were longer in patients with AF termination (95 +/- 23 and 358 +/- 87 minutes) than in patients with a <11% decrease in the DF (77 +/- 16 and 293 +/- 70 minutes) or > or =11% decrease in DF (80 +/- 17 and 289 +/- 73 minutes), respectively (P <.01). Among the variables of age, gender, left atrial diameter, duration of AF, left ventricular ejection fraction, duration of RFA, a > or =11% decrease in DF, and termination of AF, a > or =11% decrease in DF (odds ratio = 9.89, 95% confidence interval [CI] 2.84-34.47) and termination during RFA (OR = 4.38, 95% CI 1.50-12.80) were the only independent predictors of freedom from recurrent atrial arrhythmias., Conclusion: In a retrospective analysis of consecutive patients with persistent AF, a decrease in the DF of AF by 11% in response to APVI and ablation of CFAEs was associated with a probability of maintaining sinus rhythm that was similar to that when RFA terminates AF., (Copyright 2009 Heart Rhythm Society. All rights reserved.)

Background: Termination of ventricular tachycardia (VT) by mechanical pressure has been described for fascicular and postinfarction VT. Mechanical interruption of idiopathic ventricular arrhythmias (VT/premature ventricular complexes [PVCs]) arising in the right ventricular outflow tract (RVOT) has not been described in systematic fashion., Methods: Eighteen consecutive patients (13 females, age 49 +/- 13 years, ejection fraction 0.55 +/- 0.12) underwent mapping and ablation of RVOT VT or PVCs. In 7 patients, 9 distinct VTs (mean cycle length 440 +/- 127 ms), and in 11 patients, 11 distinct PVCs originating in the RVOT were targeted. Mechanical termination was considered present if a reproducibly inducible VT was no longer inducible or if frequent PVCs suddenly ceased with the mapping catheter at a particular location. Endocardial activation time, electrogram characteristics, and pace-mapping morphology were assessed at this location. Radiofrequency energy was delivered if mechanical termination was observed., Results: All targeted arrhythmias were successfully ablated. In 7 of 18 patients (39%), catheter manipulation terminated the arrhythmia with the mapping catheter located at a particular site. Local endocardial activation time was earlier at sites of mechanical termination (-31 +/- 7 ms) compared with effective sites without termination (-25 +/- 3 ms, P = 0.04). The 10-ms isochronal area was smaller in patients with mechanical interruption (0.35 +/- 0.2 cm(2)) than in patients without mechanical termination (1.33 +/- 0.9 cm(2), P = 0.01). At all sites susceptible to mechanical trauma, the pace map displayed a match with the targeted VT/PVC. All sites where mechanical termination of VT or PVCs occurred were effective ablation sites., Conclusions: Mechanical suppression at the site of origin of idiopathic RVOT arrhythmias frequently occurs during the mapping procedure and is a reliable indicator of effective ablation sites. Mechanical termination of RVOT arrhythmias may be indicative of a more localized arrhythmogenic substrate.

Background: AF can be induced by RAP or ISO in >85% of patients with PAF., Methods: ISO was administered in escalating doses of 5, 10, 15, and 20 microg/min in 112 patients (age = 56 +/- 13 years) with PAF before radiofrequency catheter ablation. AF was inducible in 97 of 112 patients (87%) at a mean dose of 15 +/- 5 microg/min. RAP induced AF in the remaining 14 of 15 patients. Antral pulmonary vein (PV) isolation (APVI) was followed by ablation of complex fractionated atrial electrograms (CFAEs) as necessary to terminate AF and render AF noninducible in response to ISO., Results: AF terminated during APVI in 72 of 111 patients (65%) and after APVI plus ablation of CFAEs in 11 of 111 patients (10%). In the remaining 28 patients (25%), sinus rhythm was restored by transthoracic cardioversion. RAP was performed in the last 61 consecutive patients who were rendered noninducible by ISO. RAP initiated AF in 20 of 61 patients (33%) and atrial flutter in 6 patients (10%). No additional ablation was performed if AF was induced with RAP; however, atrial flutter was targeted. At 12 +/- 5 months, 63/75 patients (84%) who were noninducible by ISO and 2 of 8 (25%) who still were reinducible by ISO were free from recurrent AF after a single ablation procedure without antiarrhythmic drugs (P = 0.001). AF recurred in 20 of 36 patients (56%) who required cardioversion for persistent AF after ablation (P < 0.001). Among the 61 patients who also underwent RAP, 12 of 20 (60%) who were, and 31 of 41 (76%) who were not inducible by RAP were free from recurrent AF (P = 0.21). The accuracy of noninducibility as a predictor of clinical outcome was 83% with ISO and 64% by RAP (P = 0.03)., Conclusions: The response to isoproterenol after catheter ablation of PAF more accurately predicts clinical outcome than the response to RAP.

Background: Left atrial appendage (LAA) isolation is rare and may be associated with impaired transport function and thromboembolism., Objective: The purpose of this study was to determine the mechanisms of inadvertent isolation of the LAA during atrial fibrillation (AF) ablation., Methods: This study consisted of 11 patients (ejection fraction 0.43 +/- 0.18, left atrial diameter 51 +/- 8 mm) with persistent AF who had LAA conduction block during a procedure for AF (n = 8) or atrial tachycardia (AT) (n = 3)., Results: LAA conduction block occurred during ablation at the Bachmann bundle region in 6 patients, mitral isthmus in 3, LAA base in 2, and coronary sinus in 1. The mean distance from the ablation site to the LAA base was 5.0 +/- 1.9 cm. LAA isolation was transient in all 6 patients in whom LAA conduction was monitored and was permanent in the 4 patients in whom conduction was not monitored during energy delivery. The remaining patient was noted to have LAA isolation during a redo procedure before any ablation. Nine of (82%) the 11 patients have remained arrhythmia-free without antiarrhythmic drugs at mean follow-up of 6 +/- 7 months, and all have continued taking warfarin., Conclusion: Electrical isolation of the LAA may occur during ablation of persistent AF and AT even when the ablation site is remote from the LAA. This likely is due to disruption of the Bachmann bundle and its leftward extension, which courses along the anterior left atrium and bifurcates to surround the LAA. Monitoring of LAA conduction during ablation of persistent AF or AT is important in avoiding permanent LAA isolation.

Introduction: It is unclear whether early restoration of sinus rhythm in patients with persistent atrial arrhythmias after catheter ablation of atrial fibrillation (AF) facilitates reverse atrial remodeling and promotes long-term maintenance of sinus rhythm. The purpose of this study was to determine the relationship between the time to restoration of sinus rhythm after a recurrence of an atrial arrhythmia and long-term maintenance of sinus rhythm after radiofrequency catheter ablation of AF., Methods and Results: Radiofrequency catheter ablation was performed in 384 consecutive patients (age 60 +/- 9 years) for paroxysmal (215 patients) or persistent AF (169 patients). Transthoracic cardioversion was performed in all 93 patients (24%) who presented with a persistent atrial arrhythmia: AF (n = 74) or atrial flutter (n = 19) at a mean of 51 +/- 53 days from the recurrence of atrial arrhythmia and 88 +/- 72 days from the ablation procedure. At a mean of 16 +/- 10 months after the ablation procedure, 25 of 93 patients (27%) who underwent cardioversion were in sinus rhythm without antiarrhythmic therapy. Among the 46 patients who underwent cardioversion at < or =30 days after the recurrence, 23 (50%) were in sinus rhythm without antiarrhythmic therapy. On multivariate analysis of clinical variables, time to cardioversion within 30 days after the onset of atrial arrhythmia was the only independent predictor of maintenance of sinus rhythm in the absence of antiarrhythmic drug therapy after a single ablation procedure (OR 22.5; 95% CI 4.87-103.88, P < 0.001)., Conclusion: Freedom from AF/flutter is achieved in approximately 50% of patients who undergo cardioversion within 30 days of a persistent atrial arrhythmia after catheter ablation of AF.

Background: Real-time esophageal imaging is critical in avoiding esophageal injury. However, the safety of esophageal imaging with barium has not been specifically explored., Methods: Three hundred seventy consecutive patients underwent left atrial (LA) ablation of atrial fibrillation (AF) under conscious sedation. One hundred eighty-five patients (50%) underwent the ablation procedure with, and 185 patients (50%) underwent the procedure without administration of barium. Fever, as a surrogate for aspiration, was defined as a maximal temperature >or=100 degrees F within the first 24 hours following the ablation procedure., Results: Thirty of the 370 patients (8%) developed fever within 24 hours after LA ablation. The prevalence of fever was 9% (17/185) among patients who received barium and 7% (13/185) among those who did not receive barium (P = 0.6). Evaluation revealed the following causes of fever in 14 of the 30 patients (47%) with no difference in prevalence between the 2 groups: pericarditis, venous thromboembolism, hematoma, and infiltrate on chest radiography. Multivariate analysis failed to reveal any factors associated with development of fever. None of the patients experienced serious complications such as respiratory failure or atrioesophageal fistula., Conclusions: Fever may occur in approximately 10% of patients undergoing LA ablation of AF. Administration of barium is not associated with fever or other complications such as aspiration pneumonia. Real-time imaging of the esophagus with barium administration in conjunction with conscious sedation appears to be safe.

Objectives: This study sought to determine whether ablation of complex fractionated atrial electrograms (CFAEs) after antral pulmonary vein isolation (APVI) further improves the clinical outcome of APVI in patients with long-lasting persistent atrial fibrillation (AF)., Background: Ablation of CFAEs has been reported to eliminate persistent AF. However, residual pulmonary vein arrhythmogenicity is a common mechanism of recurrence., Methods: In this randomized study, 119 consecutive patients (mean age 60 +/- 9 years) with long-lasting persistent AF underwent APVI with an irrigated-tip radiofrequency ablation catheter. Antral pulmonary vein isolation resulted in termination of AF in 19 of 119 patients (Group A, 16%). The remaining 100 patients who still were in AF were randomized to no further ablation and underwent cardioversion (Group B, n = 50) or to ablation of CFAEs in the left atrium or coronary sinus for up to 2 additional hours of procedure duration (Group C, n = 50)., Results: Atrial fibrillation terminated during ablation of CFAEs in 9 of 50 patients (18%) in Group C. At 10 +/- 3 months after a single ablation procedure, 18 of 50 (36%) in Group B and 17 of 50 (34%) in Group C were in sinus rhythm without antiarrhythmic drugs (p = 0.84). In Group A, 15 of 19 patients (79%) were in sinus rhythm. A repeat ablation procedure was performed in 34 of 100 randomized patients (for AF in 30 and atrial flutter in 4). At 9 +/- 4 months after the final procedure, 34 of 50 (68%) in Group B and 30 of 50 (60%) in Group C were in sinus rhythm without antiarrhythmic drugs (p = 0.40)., Conclusions: Up to 2 h of additional ablation of CFAEs after APVI does not appear to improve clinical outcomes in patients with long-lasting persistent AF.

Background: Left atrial (LA) ablation of atrial fibrillation (AF) may rarely be complicated by an atrio-esophageal fistula., Objective: The purpose of this study was to determine the feasibility of mechanical displacement of the esophagus in patients undergoing LA ablation., Methods: Twelve patients underwent mechanical displacement of the esophagus performed by an endoscopist during an LA ablation procedure under conscious sedation., Results: The intrinsic course of the esophagus was near the left pulmonary veins (PVs) in 6 patients, the right PVs in 5 patients, and the mid-LA in 1 patient. In 10 (83%) of the 12 patients, the esophagus could be displaced with the endoscope. The maximal displacement toward the left-sided and right-sided PVs was 2.4 and 2.1 cm, respectively. In 2 (22%) of the 9 patients in whom a prior procedure was unsuccessful because of an unfavorable esophageal course, the esophagus remained at the same location to which it was displaced after removal of the endoscope, facilitating energy delivery at the target site. In the remaining 7 patients, the esophagus returned to its original location after the endoscope was removed. There were no complications related to the endoscopic procedure., Conclusion: The esophagus can be mechanically displaced with an endoscope during an LA ablation procedure under conscious sedation. However, in most patients, the esophagus assumes its original course after removal of the endoscope. In some patients in whom PV isolation is problematic because of an unfavorable esophageal course, endoscopic displacement may facilitate safe energy delivery over the posterior LA.

Background: During catheter ablation of complex fractionated atrial electrograms, persistent atrial fibrillation (AF) may convert to an atrial tachycardia (AT)., Objective: The purpose of this study was to investigate the possible mechanisms of AT by examining the spectral and electrophysiologic characteristics of AF and ATs that occur after catheter ablation of AF., Methods: The subjects of this study were 33 consecutive patients with persistent AF who had conversion of AF to AT during ablation of AF (group I) and 20 consecutive patients who underwent ablation of persistent AT that developed more than 1 month after AF ablation (group II). Spectral analysis of the coronary sinus (CS) electrograms and lead V(1) was performed during AF at baseline, before conversion, and during AT. The spatial relationship between the AT mechanism and ablation sites was examined., Results: A spectral component with a frequency that matched the frequency of AT was present in the baseline periodogram of AF more often in group I (52%) than in group II (20%, P = .02). Ablation resulted in a decrease in the dominant frequency of AF but not in the frequency of the spectral component that matched the AT. There was a significant direct relationship between the baseline dominant frequency of AF and the frequency of AT in the CS in group I (r = 0.76, P <.0001) but not in group II (r = 0.38, P = .09). ATs were macroreentrant in 64% and 60% of patients in groups I and II, respectively (P = .8). The AT site was more likely to be distant (>1 cm) from AF ablation sites in group I (70%) than in group II (35%, P = .007)., Conclusion: The findings of this study suggest that ATs observed during ablation of AF often may be drivers of AF that become manifest after elimination of higher-frequency sources and fibrillatory conduction.

Background: There are limited data on the prevalence of atrioesophageal fistula (AEF) after left atrial radiofrequency catheter ablation for atrial fibrillation (AF). The purpose of this study was to determine the prevalence and factors associated with AEF using a nationwide anonymous survey., Methods and Results: The information solicited included the practice setting, number of left atrial ablations performed for AF, prevalence of AEF, clinical presentation and outcome of these patients, ablation strategy, type of ablation catheter, and energy settings used to deliver radiofrequency energy. The survey was mailed to 1,874 members of the Heart Rhythm Society within the US and 585 physicians responded (31%). AEF was reported in six of the 20,425 patients who underwent a left atrial ablation procedure (0.03%). All six patients suffered from major cerebrovascular events. Five of the six patients died (83%). The patient who survived had residual hemiparesis. There was no association between the risk of AEF and the case volume. In five patients, wide area circumferential ablation was performed. In the remaining patient, pulmonary vein isolation by ostial ablation was employed. In all cases an 8-mm tip ablation catheter was used. The power in patients who did and did not develop AEF were 58 +/- 13 and 41 +/- 9 W, respectively (P = 0.03). In one patient AEF occurred despite <1 degrees C rise recorded from an esophageal temperature probe. In the remaining patients no specific method was used to visualize the location of the esophagus., Conclusions: Based on the responses to the survey, the risk of AEF appears to be <1%. However, AEF is associated major cerebrovascular events and leads to death in >80% of the patients.

Background: Obesity and obstructive sleep apnea (OSA) are associated with atrial fibrillation (AF). The effects of a large body mass index (BMI) and OSA on the results of radiofrequency catheter ablation (RFA) of AF are unclear., Objective: To evaluate the effect of BMI and OSA on the efficacy of RFA for AF., Methods: RFA was performed in 324 consecutive patients (mean age = 57 +/- 11 years) with paroxysmal (234) or chronic (90) AF. OSA was diagnosed by polysomnography in 32 of 324 patients (10%) prior to ablation. Among the 324 patients, 18% had a normal BMI (<25 kg/m(2)), 39% were overweight (BMI >/= 25 kg/m(2) and <30 kg/m(2)), and 43% were obese (>or=30 kg/m(2)). RFA was performed to eliminate complex fractionated atrial electrograms (CFAE) in the pulmonary vein antrum and left atrium., Results: At 7 +/- 4 months after a single ablation procedure, 63% of patients without OSA and 41% with OSA were free from recurrent AF without antiarrhythmic drug therapy (P = 0.02). Multivariate analysis including variables of age, gender, type and duration of AF, OSA, BMI, left atrial size, ejection fraction, and hypertension demonstrated that OSA was the strongest predictor of recurrent AF (OR = 3.04, 95% CI: 1.11-8.32, P = 0.03). There was no association between BMI and freedom from recurrent AF. A serious complication occurred in 3 of 324 patients, with no relationship to BMI., Conclusions: OSA is a predictor of recurrent AF after RFA independent of its association with BMI and left atrial size. Obesity does not appear to affect outcomes after radiofrequency catheter ablation of AF.