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Aims: In patients with post-myocardial infarction (post-MI) ventricular tachycardia (VT), the presence of myocardial calcification (MC) may prevent heating of a subepicardial VT substrate contributing to endocardial ablation failure. The aims of this study were to assess the prevalence of MC in patients with post-MI VT and evaluate the impact of MC on outcome after endocardial ablation., Methods and Results: In 158 patients, the presence of MC was retrospectively assessed on fluoroscopy recordings in seven standard projections obtained during pre-procedural coronary angiograms. Myocardial calcification, defined as a distinct radiopaque area that moved synchronously with the cardiac contraction, was detected in 30 patients (19%). After endocardial ablation, only 6 patients (20%) with MC were rendered non-inducible compared with 56 (44%) without MC (P = 0.033) and of importance, 8 (27%) remained inducible for the clinical VT [compared with 9 (6%) patients without MC; P = 0.003] requiring therapy escalation. After a median follow-up of 31 months, 61 patients (39%) had VT recurrence and 47 (30%) died. Patients with MC had a lower survival free from the composite endpoint of VT recurrence or therapy escalation at 24-month follow-up (26% vs. 59%; P = 0.003). Presence of MC (HR 1.69; P = 0.046), a lower LV ejection fraction (HR 1.03 per 1% decrease; P = 0.017), and non-complete procedural success (HR 2.42; P = 0.002) were independently associated with a higher incidence of VT recurrence or therapy escalation., Conclusion: Myocardial calcification was present in 19% of post-MI patients referred for VT ablation and was associated with a high incidence of endocardial ablation failure., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions, please email: journals.permissions@oup.com.)

Background: J-waves and fragmented QRS (fQRS) on surface ECGs have been associated with the occurrence of ventricular tachyarrhythmias. Whether these non-invasive parameters can also predict ventricular tachycardia (VT) recurrence after radiofrequency catheter ablation (RFCA) is unknown. Of interest, patients with a wide QRS-complex have been excluded from clinical studies on J-waves, although a J-wave like pattern has been described for wide QRS., Methods: We retrospectively included 168 patients (67 ± 10 years; 146 men) who underwent RFCA of post-infarct VT. J-wave pattern were defined as J-point elevation ≥ 0.1 mV in at least two leads irrespective of QRS width. fQRS was defined as various RSR` pattern in patients with narrow QRS and more than two R wave in those with wide QRS. The primary endpoint was VT recurrence after RFCA up to 24 months., Results: J-wave pattern and fQRS were present in 27 and 28 patients, respectively. Overlap of J-wave pattern and fQRS was observed in nine. During a median follow-up of 20 (interquartile range 9-24) months, 46 (27%) patients had VT recurrence. Kaplan-Meier curves revealed that both J-wave pattern and fQRS were associated with VT recurrence. Multivariate Cox regression analysis demonstrated that the presence of J-wave pattern (hazard ratio [HR] 2.84; 95% confidence interval [CI] 1.45-5.58; P = .002) and greater number of induced VT (HR 1.29; 95% CI 1.15-1.45; P < .001) were the independent predictors of VT recurrence., Conclusions: A J-wave pattern-but not fQRS-is independently associated with an increased risk of post-infarct VT recurrence after RFCA irrespective of QRS width. This simple non-invasive parameter may identify patients who require additional treatment., (© 2021 The Authors. Pacing and Clinical Electrophysiology published by Wiley Periodicals LLC.)

Objectives: The purpose of this study was to randomly compare the incidence of asymptomatic cerebral embolism (ACE) between the second-generation pulmonary vein ablation catheter (PVAC Gold) and the irrigated Thermocool catheter., Background: Pulmonary vein isolation (PVI) with the PVAC is associated with ACE. The PVAC Gold was designed to avoid this complication., Methods: Patients with paroxysmal atrial fibrillation were randomized 1:1 to PVI with the PVAC Gold or Thermocool catheter. Cerebral magnetic resonance imaging was performed in the days before and after ablation and repeated after 3 months in case of a new lesion. Monitoring for microembolic signals (MES) was performed by using transcranial Doppler ultrasonography. Parameters of coagulation were determined before, during, and after ablation. Neuropsychological tests and questionnaires were applied 10 days before and 3 months after ablation., Results: Seventy patients were included in the study (mean age 61 ± 9 years; 43 male subjects; CHA 2 DS 2 -VASc [congestive heart failure, hypertension, age ≥75 years, diabetes mellitus, stroke/transient ischemic attack, vascular disease, age 65 to 74 years, sex category] score 1.6 ± 1.2; international normalized ratio 2.7 ± 0.5; activated clotting time 374 ± 24 s; p > 0.05 for all parameters). Procedural duration was shorter in the PVAC Gold group (140 ± 34 vs. 207 ± 44 min; p < 0.001). Eight (23%; 7 infarcts) patients in the PVAC Gold group exhibited a new ACE, compared with 2 (6%; no infarcts) patients in the Thermocool group (p = 0.042). Median number of MES was higher in the PVAC Gold group (1,111 [interquartile range, 715-2,234] vs. 787 [interquartile range, 532-1,053]; p < 0.001). There were no differences between groups regarding coagulation and neuropsychological outcomes., Conclusions: PVI with the new PVAC Gold was associated with a higher incidence of ACE/cerebral infarcts and number of MES. Both catheters induced a comparable procoagulant state. Because there were no measurable differences in neuropsychological status, the clinical significance of ACE remains unclear. (Cerebral Embolism [CE] in Catheter Ablation of Atrial Fibrillation [AF] [CE-AF]; NCT01361295)., (Copyright © 2019 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: The posterior wall of the left atrium (LA) is a well-known substrate for atrial fibrillation (AF) maintenance. Isolation of the posterior wall between the pulmonary veins (box lesion) may improve ablation success. Box lesion surface area size varies depending on the individual anatomy. This retrospective study evaluates the influence of box lesion surface area as a ratio of total LA surface area (box surface ratio) on arrhythmia recurrence., Methods: Seventy consecutive patients with persistent AF (63 ± 11 years, 53 men) undergoing computed tomography (CT) imaging and ablation procedure consisting of a first box lesion were included in this study. Box lesion surface area was measured on electroanatomical maps and total LA surface area was derived from CT. Patients were followed with 24-h electrocardiography and exercise tests at 3, 6, and 12 months after AF ablation. Arrhythmia recurrence was defined as any AF/atrial tachycardia (AT) beyond 3 months without antiarrhythmic drugs., Results: During a median follow-up of 13 (interquartile range = 10-17) months, 42 (60%) patients had AF/AT recurrence. Multivariate Cox proportional regression analysis showed that a larger box surface ratio protected against recurrence (hazard ratio [HR] = 0.81; 95% confidence interval [CI] = 0.690-0.955; P = 0.012). Left atrial volume index (HR = 1.01 [0.990-1.024, P = 0.427] and a history of mitral valve surgery (HR = 2.90; 95% CI = 0.970-8.693; P = 0.057) were not associated with AF recurrence in multivariate analysis., Conclusion: A larger box lesion surface area as a ratio of total LA surface area is protective for AF/AT recurrence after ablation for persistent AF., (© 2018 The Authors. Pacing and Clinical Electrophysiology published by Wiley Periodicals, Inc.)

Background: Noninducibility of ventricular tachycardia (VT) with an equal or longer cycle length (CL) than that of the clinical VT is considered the minimum ablation endpoint in patients with structural heart disease. Because their clinical relevance remains unclear, fast nonclinical VTs are often not targeted. However, an accepted definition for fast VT is lacking. The shortest possible CL of a monomorphic reentrant VT is determined by the ventricular refractory period (VRP)., Objective: The purpose of this study was to propose a patient-specific definition for fast VT based on the individual VRP (fVT VRP ) and assess the prognostic significance of persistent inducibility after ablation of fVT VRP for VT recurrence., Methods: Of 191 patients with previous myocardial infarction or with nonischemic cardiomyopathy undergoing VT ablation, 70 (age 63 ± 13 years; 64% ischemic) remained inducible for a nonclinical VT and composed the study population. FVT VRP was defined as any VT with CL ≤VRP 400 + 30 ms. Patients were followed for VT recurrence., Results: After ablation, 30 patients (43%) remained inducible exclusively for fVT VRP and 40 (57%) for any slower VT. Patients with only fVT VRP had 3-year VT-free survival of 64% (95% confidence interval [CI] 46%-82%) compared to 27% (95% CI 14%-48%) for patients with any slower remaining VT (P = .013). Inducibility of only fVT VRP was independently associated with lower VT recurrence (hazard ratio 0.38; 95% CI 0.19-0.86; P = .019). Among 36 patients inducible for any fVT VRP , only 1 had recurrence with fVT VRP ., Conclusion: In patients with structural heart disease, inducibility of exclusively fVT VRP after ablation is associated with low VT recurrence., (Copyright © 2018 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Objectives: This study sought to determine whether ablation of hidden substrate unmasked by right ventricular extrastimulation (RVE) improves ablation outcome of post-myocardial infarction (MI) ventricular tachycardia (VT)., Background: In patients with small or nontransmural scars after MI, part of the VT substrate may be functional and, in addition, masked by high-voltage far-field signals arising from adjacent normal myocardium., Methods: In 60 consecutive patients, systematic analysis of electrograms recorded from the presumed infarct area was performed during sinus rhythm, RV pacing at 500 ms, and during a short-coupled RV extrastimulus. Sites showing low-voltage, near-field potentials with evoked conduction delay in response to RVE were targeted., Results: In 37 (62%) patients, ablation target sites located in areas with normal voltage during sinus rhythm were unmasked by RVE (hidden substrate group). These patients had better left ventricular function (36 ± 11% vs. 26 ± 12%; p = 0.003), smaller electroanatomical scars (<1.5 mV), and smaller dense scars (<0.5 mV) (median 59 and 14 cm 2 vs. 82 and 44 cm 2 ; p = 0.044 and p = 0.003) than did those in whom no hidden substrate was identified (overt substrate group). During a median follow-up of 16 months, 13 (22%) patients had VT recurrence. Patients with hidden substrate had a lower incidence of VT recurrence (12-month VT-free survival 89% vs. 50% in patients with overt substrate; p = 0.005). Compared with a historical cohort of 90 post-MI patients matched for left ventricular function and electroanatomical scar area, in whom no RVE was performed, patients in the hidden substrate group had a higher 1-year VT-free survival (89% vs. 73%; p = 0.039)., Conclusions: Hidden substrate ablation unmasked by RVE improves ablation outcome in post-MI patients with small or nontransmural scars., (Copyright © 2018 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: Recently, a new ablation strategy for atrial fibrillation has emerged, which involves the identification of rotors (ie, local drivers) followed by the localized targeting of their core region by ablation. However, this concept has been subject to debate because the mode of arrhythmia termination remains poorly understood, as dedicated models and research tools are lacking. We took a unique optogenetic approach to induce and locally target a rotor in atrial monolayers., Methods and Results: Neonatal rat atrial cardiomyocyte monolayers expressing a depolarizing light-gated ion channel (Ca 2+ -translocating channelrhodopsin) were subjected to patterned illumination to induce single, stable, and centralized rotors by optical S1-S2 cross-field stimulation. Next, the core region of these rotors was specifically and precisely targeted by light to induce local conduction blocks of circular or linear shapes. Conduction blocks crossing the core region, but not reaching any unexcitable boundary, did not lead to termination. Instead, electric waves started to propagate along the circumference of block, thereby maintaining reentrant activity, although of lower frequency. If, however, core-spanning lines of block reached at least 1 unexcitable boundary, reentrant activity was consistently terminated by wave collision. Lines of block away from the core region resulted merely in rotor destabilization (ie, drifting)., Conclusions: Localized optogenetic targeting of rotors in atrial monolayers could lead to both stabilization and destabilization of reentrant activity. For termination, however, a line of block is required reaching from the core region to at least 1 unexcitable boundary. These findings may improve our understanding of the mechanisms involved in rotor-guided ablation., (© 2017 American Heart Association, Inc.)

Aims: Limited left atrial (LA) surgical ablation with bipolar radiofrequency is considered to be an effective procedure for treatment of atrial fibrillation (AF). We studied whether limited LA surgical ablation concomitant to cardiac surgery is able to maintain LA function., Methods and Results: Thirty-six consecutive patients (age 66 ± 12 years, 53% male, 78% persistent AF) scheduled for valve surgery and/or coronary revascularization and concomitant LA surgical ablation were included. Epicardial pulmonary vein isolation (PVI) and additional endo-epicardial lines were performed using bipolar radiofrequency. An age- and gender-matched control group (n = 36, age 66 ± 9 years, 69% male, 81% paroxysmal AF) was selected from patients undergoing concomitant epicardial PVI only. Left atrial dimensions and function were assessed on two-dimensional echocardiography preoperatively and at 3- and 12-month follow-up. Sinus rhythm (SR) maintenance was 67% for limited LA ablation and 81% for PVI at 1-year follow-up (P = 0.18). Left atrial volume decreased from 72 ± 21 to 50 ± 14 mL (31%, P < 0.01) after limited LA ablation and from 65 ± 23 to 56 ± 20 mL (14%, P < 0.01) after PVI. Atrial transport function was restored in 54% of patients in SR after limited LA ablation compared with 100% of patients in SR after PVI. Atrial strain and contraction parameters (LA ejection fraction, A-wave velocity, reservoir function, and strain rate) significantly decreased after limited LA ablation. After PVI, strain and contraction parameters remained unchanged., Conclusion: Even limited LA ablation decreased LA volume, contraction, transport function, and compliance, indicating both reverse remodelling combined with significant functional deterioration. In contrast, surgical PVI decreased LA volume while function remained unchanged., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For permissions please email: journals.permissions@oup.com.)

Background: Noninducibility is frequently used as procedural end point of ventricular tachycardia (VT) ablation after myocardial infarction. We investigated the influence of left ventricular (LV) function on the predictive value of noninducibility for VT recurrence and cardiac mortality., Methods and Results: Ninety-one patients (82 men, 67±10 years) with post-myocardial infarction VT underwent ablation between 2009 and 2012. Fifty-nine (65%) had an LV ejection fraction (EF) >30% (mean 41±7) and 32 (35%) an LVEF≤30% (mean 20±5). Thirty patients (51%) with EF>30% and 13 (41%) with EF≤30% were noninducible after ablation (P=0.386). During a median follow-up of 23 (Q1-Q3 16-36) months, 35 patients (38%) experienced VT recurrences and 17 (18%) cardiac death. At 1 year follow-up, survival free from VT recurrence and cardiac death for patients with LVEF>30% was 80% (95% confidence interval [CI], 70-90) compared with 42% (95% CI, 33-51) for those with LVEF≤30% (P=0.001). Noninducible patients with LVEF>30% had a recurrence-free survival from cardiac death of 90% (95% CI, 71-100) compared with 65% (95% CI, 47-83) for inducible patients (P=0.015). In the subgroup of patients with LVEF≤30%, the survival free from VT recurrence and cardiac death was 31% (95% CI, 0%-60%) for noninducible compared with 39% (95% CI, 27-52) for those who remained inducible (P=0.842)., Conclusions: Noninducible patients with moderately depressed LV function have a favorable outcome compared with patients who remained inducible after ablation. On the contrary, patients with severely depressed LV function have a poor prognosis independent of the acute procedural outcome., (© 2015 American Heart Association, Inc.)

Background: Radiofrequency catheter ablation (RFCA) of ventricular tachycardia (VT) in repaired Tetralogy of Fallot focuses on isthmuses in the right ventricle but may be hampered by hypertrophied myocardium or prosthetic material. These patients may benefit from ablation at the left side of the ventricular septum., Methods and Results: Records from 28 consecutive repaired Tetralogy of Fallot patients from 2 centers who underwent VT ablation were reviewed. Ablation targeted anatomic isthmuses containing VT re-entry circuits, which were identified by 3-dimensional substrate, pace, and entrainment mapping. A left-sided approach was considered beneficial if (1) right-sided RFCA failed, (2) part of the circuit was mapped to the left side, and (3) left-sided RFCA resulted in isthmus transection and prevention of VT induction. In 4 of 28 patients (52±13 years; 75% men), inducible for 1.5 (quartiles, 1.0 - 2.0) VTs (335±58 ms), left-sided RFCA was performed. In 3 patients, RFCA at aortic sites terminated VT related to a septal isthmus and prevented reinduction. In 1 patient, with prior biventricular implantable cardioverter-defibrillator, diastolic activity was recorded at the left side of the septum in proximity to the His-bundle. RFCA prevented VT reinduction with anticipated complete atrioventricular block. The left-sided approach resulted in complete procedural success (transection of anatomic isthmus and noninducibility) and freedom of VT recurrence during follow-up (20±15 months) in all patients. Right-sided RFCA failure was likely because of septal hypertrophy in 2, overlying pulmonary homograft in 1, and overlying ventricular septal defect patch in 1., Conclusions: Left-sided RFCA for VTs dependent on septal anatomic isthmuses improves ablation outcome in repaired Tetralogy of Fallot., (© 2014 American Heart Association, Inc.)

The underlying mechanism of mitral regurgitation (MR) because of isolated annulus dilation (Carpentier type I) remains controversial in patients with atrial fibrillation (AF). The present study evaluated changes in mitral valve geometry of patients with AF and structurally and functionally normal left ventricles and mitral leaflets. Grade of MR and left ventricular (LV) function was evaluated with echocardiography. Changes in mitral valve geometry were evaluated with multidetector row computed tomography (MDCT) performed before radiofrequency catheter ablation for AF. From a cohort of 480 patients with drug-refractory AF referred for catheter ablation, 170 patients (mean age 58 ± 10 years, 67% men) with structural and functional normal left ventricles and mitral leaflets were included. The intercommissural and anteroposterior diameter, perimeter, and area of the mitral annulus and left atrial volume were assessed with MDCT and correlated with the grade of MR as assessed with echocardiography. A total of 49 patients (29%) had MR ≥2+. These patients had larger mitral annulus area compared with patients with MR <2+ (665.0 ± 100.6 mm(2)/m(2) vs 530.5 ± 66.6 mm(2)/m(2), p <0.001), whereas LV size and function (ejection fraction 64.9 ± 6.3% vs 63.1 ± 5.7%, p = 0.08) were similar. After adjusting for age, type of AF, hypertension, left atrial volume, and LV end-systolic volume and ejection fraction, the mitral annulus dimensions remained independently correlated with MR ≥2+. In conclusion, in AF patients with structural and functional normal left ventricles and mitral leaflets, MDCT demonstrated that mitral annulus dilation is independently associated with type I MR., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Background: This study evaluates the influence of 3 therapeutic approaches on the incidence of pericarditis and atrial fibrillation (AF) after percutaneous epicardial mapping and ablation for ventricular tachycardia., Methods and Results: Eighty-five consecutive procedures (2006-2011) were retrospectively reviewed. After the first 17 procedures (20.0%), no steroids were administered. For the subsequent 30 procedures (35.3%), systemic steroids were administered intravenously or orally, whereas the last 38 procedures (44.7%) were followed by intrapericardial steroid injection. Compared with no steroids, the incidence of pericarditic chest pain was significantly reduced by intrapericardial steroids (58.8% versus 21.1%; P=0.006) but not by intravenous or oral steroids (58.8% versus 43.4%; P=0.31). There was no significant difference in the incidence of pericarditic ECG with steroids (36.8%, 30.0%, and 41.2% for intrapericardial, intravenous or oral, and none, respectively). There was a nonsignificant reduced incidence of chest pain with ECG changes with steroids (13.2%, 10.0%, and 29.4% for intrapericardial, intravenous or oral, and none, respectively). Radiofrequency applications (65.9% of procedures) did not affect the incidence of pericarditic ECG changes, pericarditic chest pain, or pericarditis (all P>0.05). In 7 (8.3%) patients with no prior history of AF, AF was documented a median 36 hours after procedure. Patients with pericarditic ECG tended to be at greater risk of AF (16.7 versus 3.6%; P=0.091)., Conclusions: There is a high incidence of pericarditic chest pain and ECG changes after epicardial ventricular tachycardia mapping and ablation. Pericarditic chest pain is significantly decreased by intrapericardial steroids. Procedure-related AF is relatively frequent and tends to occur more commonly with pericarditic ECG changes., (© 2014 American Heart Association, Inc.)

Background: There are limited data on typical arrhythmogenic substrates and associated ventricular tachycardias (VT) in patients with nonischemic cardiomyopathy. The substrate location may have implications for the ablation strategy., Methods and Results: Nineteen consecutive patients with nonischemic cardiomyopathy (age 58±14 years, 79% men, left ventricular ejection fraction 41±11%) who underwent contrast-enhanced MRI and VT ablation were included. On the basis of 3-dimensional contrast-enhanced MRI-derived scar reconstructions, 8 patients (42%) had predominant basal anteroseptal scar, 9 patients (47%) had predominant inferolateral scar, and 2 patients (11%) had other scar types. Three distinct VT morphologies (≥1 of 3 inducible in 16/19 patients) were associated with underlying scar type. In 9 patients with anteroseptal scar-related VT (8/9 predominant scar, 1/9 nonpredominant), ablation target sites (defined as sites with ≥11/12 pacemap, concealed entrainment or VT termination during ablation) were located in the aortic root and/or anteroseptal left ventricular endocardium in 8 patients (89%) and in the anterior cardiac vein in 1 patient (11%), with additional target sites at the right ventricular septum in 2 patients (22%) and at the epicardium in 1 patient (11%). In contrast, in 8 patients with predominant inferolateral scar-related VT, target sites were located at the epicardium in 5 patients (63%) and in the endocardial inferolateral left ventricle in 3 patients (37%)., Conclusions: Two typical scar patterns (anteroseptal and inferolateral) account for 89% of arrhythmogenic substrates in patients with nonischemic cardiomyopathy. Three distinct VT morphologies are highly suggestive of the presence of these scars. Anteroseptal scars were, in general, most effectively approached from the aortic root or anteroseptal left ventricular endocardium, whereas inferolateral scars frequently required an epicardial approach.

Background: Ablation failure and recurrence rates after ventricular tachycardia (VT) ablation in nonischemic cardiomyopathy are high and the optimal procedural end point is not well defined. This study assessed the outcome after ablation, the impact of noninducibility, and other potential predictors of VT recurrence., Methods and Results: Forty-five patients with nonischemic cardiomyopathy (60±16 years; left ventricular ejection fraction, 44±14%) accepted for VT ablation were included. Epicardial mapping was performed in 29 (64%). A median of 2 (first-to-third quartile, 2-4) VTs (cycle length, 342±77 ms) were induced per patient. After ablation, the complete programmed electric stimulation protocol (3 drive cycle length, 3 extrastimuli ≥200 ms, and burst≥2 sites) was repeated. Complete success (noninducibility of any monomorphic VT) was achieved in 17 patients (38%), partial success (elimination of clinical VT, persistent inducibility of nonclinical VT) in 17 patients (38%), and failure (persistent inducibility of clinical VT) in 11 patients (24%). During 25±15 months of follow-up, VT occurred in 24 patients (53%), but the 6-month VT burden was reduced by ≥75% in 79%. Recurrence rates were low after complete procedural success (18%), but high after both partial success (77%) and failure (73%). Non-complete procedural success was the strongest predictor of VT recurrence (hazard ratio, 8.20; 95% confidence interval, 2.37-28.43; P=0.001)., Conclusions: Although 53% of patients had VT during follow-up, the 6-month VT burden was decreased by ≥75% in 79%. Recurrence rates are low after complete procedural success, but high after both partial success and failure. Non-complete procedural success was the strongest predictor of VT recurrence.

Aims: A novel duty-cycled bipolar/unipolar ablation catheter pulmonary vein ablation catheter (PVAC) has been developed to achieve pulmonary vein (PV) isolation in patients with atrial fibrillation (AF). Ablation with PVAC was recently found to induce PV narrowing at 3 months follow-up. The long-term effects of this catheter on PV dimensions are however unknown and were evaluated with this study., Methods and Results: Patients (n = 62, 71% male, age 60 ± 7 years) with drug-refractory AF scheduled for a first ablation procedure were evaluated. A multi-slice computed tomography (MSCT) scan was performed before and 1 year after the initial procedure. Pulmonary vein dimensions and left atrial (LA) volume were measured on MSCT. To correct for reverse remodelling of the LA, the ostial area/LA volume ratio before and after PVAC was calculated. As reverse remodelling may depend on procedural outcome, patients were divided in two groups depending on sinus rhythm (SR) maintenance or AF recurrence 1 year after ablation. Baseline characteristics were comparable between the SR group (n = 41) and the AF recurrence group (n = 21). At one year follow-up, ostial area of the PVs (n = 219) was significantly reduced from 236 ± 7.0 to 173 ± 7.4 mm(2) (27% narrowing, P < 0.01), independent of ablation outcome. Pulmonary vein narrowing was mild in 37% of PVs (25-50%), 9% was moderate (50-70%), and 3% severe (>70%). Left atrial volumes were found to be significantly reduced after ablation (14 and 5% for the SR group and AF recurrence group, respectively, P < 0.01). After adjustment for LA volume reduction, narrowing of PV ostial area remained significant in these patients (P < 0.01)., Conclusion: Ablation with PVAC results in a significant decrease in PV dimensions after long-term follow-up. In line with previous literature, PV narrowing was mild and patients did not develop any clinical symptoms.

Aims: Coronary atherosclerosis has been associated with the development of atrial fibrillation (AF). However, little is known about the impact of coronary atherosclerosis on the outcome treatment of AF. The aim of this study was to investigate the impact of coronary atherosclerosis on the efficacy of radiofrequency catheter ablation (RFCA) for AF using multi-detector row computed tomography (MDCT)., Methods: In 125 consecutive patients undergoing RFCA for AF, a pre-procedural MDCT examination (coronary angiography and/or coronary calcium score) was performed to evaluate the presence and severity of coronary atherosclerosis. Furthermore, all patients underwent a comprehensive echocardiographic evaluation to measure the left atrial size and to rule out structural heart disease. After RFCA all patients were regularly evaluated at the outpatient clinic., Results: After a mean follow-up of 12 ± 3 months, 78 patients (62%) had maintained stable sinus rhythm and 47 patients (38%) had recurrence of AF. Left atrial volume index was a significant predictor of AF recurrence after RFCA. The presence of coronary atherosclerosis on MDCT did not influence the efficacy of RFCA for AF., Conclusions: The presence of coronary atherosclerosis on MDCT is not associated with a higher risk for AF recurrence after RFCA.

Aims: During epicardial electroanatomical mapping (EAM), it is difficult to differentiate between fibrosis and fat, as both exhibit attenuated bipolar voltage (BV). The purpose of this study was to assess whether unipolar voltage (UV), BV, and electrogram characteristics (EC) can distinguish fibrosis from viable myocardium and fat during epicardial EAM for ventricular tachycardia (VT) ablation in non-ischaemic cardiomyopathy (NICM)., Methods and Results: Ten NICM patients (7 males, 56 ± 13 years) with VT underwent epicardial EAM with real-time integration of computed tomography-derived epicardial fat and contrast-enhanced MRI-derived scar. Bipolar voltage (filtered 30-400 Hz), UV (filtered 1-240 Hz), and EC (duration and morphology) were correlated with the presence of fat and scar. At sites devoid of fat, the optimal cutoff values to differentiate between scar and myocardium were 1.81 mV for BV and 7.95 mV for UV. Bipolar voltage, UV, and electrogram duration >50 ms distinguished scar from myocardium in areas covered with <2.8 mm fat (all P < 0.001), but not ≥ 2.8 mm fat. In contrast, electrogram morphology-characteristics could also detect scar covered with ≥ 2.8 mm fat (P = 0.001). A newly developed three-step algorithm combining electrogram morphology, duration, and UV could correctly identify scar with a sensitivity of 75%. Unipolar voltage but not BV could detect intramural scar in the absence of fat., Conclusions: Both BV ≤ 1.81 mV and UV ≤ 7.95 mV are useful for detection of scar during epicardial EAM, in the absence of ≥ 2.8 mm fat. However, EC can be used to detect scar covered with fat. A newly developed algorithm combining UV and EC can differentiate between scar and viable myocardium. Unipolar voltage but not BV could detect intramural scar.

Objectives: This study aimed to evaluate the feasibility and accuracy of real-time integration of multidetector computed tomography (MDCT) derived coronary anatomy and epicardial fat distribution and its impact on electroanatomical mapping and ablation., Background: Epicardial catheter ablation for ventricular arrhythmias (VA) is an important therapeutic option in patients after endocardial ablation failure. However, epicardial mapping and ablation are limited by the presence of coronary arteries and epicardial fat., Methods: Twenty-eight patients (21 male, age 59 ± 16 years) underwent combined endo-epicardial electroanatomical mapping. Prior to the procedure, MDCT derived coronary anatomy and epicardial fat meshes were loaded into the mapping system (CARTO XP, Biosense Webster Inc, Diamond Bar, California). Real-time registration of MDCT data was performed after endocardial mapping. The distance between epicardial ablation sites and coronary arteries was assessed by registered MDCT and angiography. After the procedure, mapping and ablation points were superimposed on the MDCT using a reversed registration matrix for head-to-head comparison of mapping data and corresponding fat thickness., Results: Image registration was successful and accurate in all patients (position error 2.8 ± 1.3 mm). At sites without evidence for scar, epicardial bipolar voltage decreased significantly (p < 0.001) with increasing fat thickness. Forty-six VA were targeted; 25 (54%) were abolished by catheter ablation, in 21 (46%) ablation failed. In 5 VA no target site was identified and in 3 VA adhesions prevented mapping. In 2 VA ablation was withheld due to His-bundle vicinity and in 7 VA due to proximity of coronary arteries. In 4 VA catheter ablation was ineffective. At ineffective ablation sites epicardial fat was significantly thicker compared to successful sites (16.9 ± 6.8 mm [range 7.3 to 22.2 mm] and 1.5 ± 2.1 mm [range 0.0 to 6.1 mm], p = 0.002)., Conclusions: Real-time image integration of pre-acquired MDCT information is feasible and accurate. Epicardial fat >7 mm and the presence of coronary arteries are important reasons for epicardial ablation failure. Visualization of fat thickness during the procedure may facilitate interpretation of bipolar electrograms and identification of ineffective ablation sites., (Copyright © 2013 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

A case of radiofrequency catheter ablation of atrioventricular (AV) nodal reentry tachycardia, in a patient with transposition of the great arteries after venous rerouting according to Mustard, is described. An electroanatomical map of the His and AV nodal region was created from inside the systemic venous atrium. Retrograde mapping of the pulmonary venous atrium was performed and the arterial catheter retracted to a position in close proximity to the venous catheter inside the intraatrial baffle. This position was chosen to deliver radiofrequency current., (©2010, The Authors. Journal compilation ©2012 Wiley Periodicals, Inc.)

Aim: Post-operative atrial tachyarrhythmias (AT) in patients with tetralogy of Fallot (ToF) are associated with congestive heart failure, stroke, and cardiac death. Effective treatment is therefore essential. The aim of the study is to evaluate long-term outcome of ablative therapy of AT in ToF patients and to study characteristics of AT recurrences., Methods and Results: Tetralogy of Fallot patients (N = 38, age 43 ± 12 years) referred for ablation of post-operative AT, appearing 26 ± 10 years after complete repair, were studied. Electro-anatomical/entrainment mapping was performed prior to ablation. Successful ablation was defined as (i) achievement of bi-directional conduction block for isthmus-dependent atrial flutter (IDAF), (ii) termination during ablation for intra-atrial reentrant tachycardia (IART) and focal atrial tachycardia (FAT). Fifty-two AT were ablated, including 37 IDAF [cycle length (CL) 294 ± 70 ms], 11 IART (CL 295 ± 46 ms), and 4 FAT (CL 371 ± 93 ms). Ablation was successful in 98%. Fifty-one of 52 AT involved the cavo-tricuspid isthmus and/or the area between scar tissue related to prior atriotomy incisions and the inferior caval vein. Multiple AT developed in 11 patients, with different mechanisms in 9. After 45 ± 24 months, 32 patients were in sinus rhythm; 5 used anti-arrhythmic drugs., Conclusion: Ablative therapy of AT in ToF patients is an effective curative treatment modality with a high procedural success rate. Sinus rhythm during long-term follow-up was obtained in the majority of patients. Fifty-one of 52 AT originated from sites related to surgical incisions created at complete repair, suggesting that extending the atriotomy incision towards the inferior caval vein during cardiac surgery combined with surgical ablation of the cavo-tricuspid isthmus will be effective in preventing development of AT.

Background: After surgical ventricular restoration (SVR) for ischemic cardiomyopathy, ventricular tachycardias (VTs) are an important reason for postoperative morbidity and mortality., Objective: The purpose of this study was to elucidate the VT substrate, VT characteristics, and outcome of radiofrequency catheter ablation (RFCA) in patients with VT after SVR., Methods: Twelve (3%) of 416 patients referred for RFCA for VT after myocardial infarction in three centers had undergone SVR. After induction of VT, left ventricular (LV) electroanatomical mapping was performed. Ablation target sites were identified by entrainment, substrate, and/or pace mapping., Results: Four (33%) patients presented within the perioperative period with incessant VT, and eight (67%) presented with incessant or recurrent VT late after SVR (VT cycle length 453 ± 102 ms). The region of surgical scar was identified by electroanatomical mapping in 11 patients. Twenty-eight VTs (cycle length 384 ± 95 ms) were induced. The VT exit was bordering the surgical scar in 20 (71%) VTs, of which 15 were at the septal side. All VTs were abolished in five patients: in four only the clinical VTs were abolished, and in one reinducibility was not tested. In two patients, ablation failed after which surgical ablation was performed successfully. During follow-up, three (25%) patients died (nonarrhythmic deaths); all had presented early after SVR. Two (17%) experienced recurrent VT., Conclusion: VT after LV SVR seems to have a bimodal presentation; one-third presented with incessant VT in the acute postoperative phase and had a high mortality. Two-thirds presented late after SVR; in these patients RFCA is usually effective. Successful ablation sites are frequently located at the border of surgical scars and patch material., (Crown Copyright © 2012. Published by Elsevier Inc. All rights reserved.)

Background: Left atrial (LA) dilatation is an important risk factor for recurrence of atrial fibrillation (AF) after radiofrequency catheter ablation (RFCA). However, the clinical applications to select patients eligible for RFCA according to LA size is limited. Additional pre-procedural assessment of LA fibrosis might improve patient selection for RFCA., Objective: To investigate the impact of LA size and LA fibrosis on the outcome of RFCA for AF., Methods: One hundred and seventy consecutive patients undergoing RFCA for AF were studied. LA size was assessed by measuring maximum LA volume index on echocardiography. LA wall ultrasound reflectivity was assessed by measuring echocardiography-derived calibrated integrated backscatter (IBS) as a surrogate of LA fibrosis., Results: After 12±3 months' follow-up, 103 patients (61%) had maintained sinus rhythm and 67 patients (39%) had recurrence of AF. Univariate Cox analyses identified LA wall ultrasound reflectivity, as well as LA size and type of AF, as predictors of AF recurrence after RFCA. Importantly, multivariate analyses showed that LA wall ultrasound reflectivity remained a strong predictor after correction for LA size and type of AF. Moreover, LA wall ultrasound reflectivity provided an incremental value in predicting outcome of RFCA over LA size and type of AF (increment in global χ(2)=61.6, p<0.001)., Conclusion: Assessment of LA fibrosis using two-dimensional echocardiography-derived calibrated IBS can be useful to predict AF recurrence after RFCA. Combined assessment of LA wall ultrasound reflectivity and LA size improves the identification of patients with a high likelihood for a successful ablation.

Aims: Total atrial activation time has been identified as an independent predictor of new-onset atrial fibrillation (AF). Echocardiographic assessment of PA-TDI duration provides an estimation of total atrial conduction time. The aim of this study was to investigate the prognostic value of total atrial conduction time to predict AF recurrence after radiofrequency catheter ablation (RFCA)., Methods and Results: In 213 patients undergoing RFCA for symptomatic drug-refractory paroxysmal AF, the total atrial conduction time was estimated by measuring the time delay between the onset of the P-wave in lead II of the surface electrocardiogram and the peak A'-wave on the tissue Doppler tracing of the left atrial (LA) lateral wall (PA-TDI duration). After RFCA, all patients were evaluated on a systematic basis at the outpatient clinic. After a mean follow-up of 13 ± 3 months, 74 patients (35%) had recurrent AF whereas 139 patients (65%) maintained sinus rhythm. Left atrial maximum volume index and PA-TDI duration were identified as independent predictors of AF recurrence after RFCA. However, receiver operator characteristics curve analyses demonstrated that PA-TDI duration had a superior accuracy to predict AF recurrence compared with LA maximum volume index (area under the curve 0.765 vs. 0.561, respectively)., Conclusion: Assessment of total atrial conduction time using tissue Doppler imaging can be used to predict AF recurrence after RFCA.

Background: Radiofrequency catheter ablation (RFCA) for idiopathic right ventricular outflow tract (RVOT) arrhythmias is typically guided by local activation time (LAT) mapping and unipolar electrogram morphology (QS configuration). However, LAT mapping is limited by the large variation among patients, and the area demonstrating a QS configuration of the unipolar electrogram may be larger than the focal source. Reversed polarity has been proposed as a criterion for guiding RFCA., Objective: The purpose of this study was to investigate the value of reversed polarity of adjacent bipolar electrograms for predicting a successful ablation site in idiopathic RVOT arrhythmias., Methods: Twenty-five consecutive patients (12 men [48%], age 43 ± 15 years) undergoing RFCA for RVOT arrhythmia were studied. Electrograms of ablation sites and of points within a 15-mm radius to the successful site were evaluated for LAT, unipolar electrogram morphology, and the presence of reversed polarity of adjacent bipolar electrograms. Electrogram characteristics of successful ablation sites were compared to those of nonsuccessful ablation sites. The spatial distribution of each electrogram characteristic was studied., Results: Successful ablation sites more often demonstrated reversed polarity and had an earlier LAT than nonsuccessful sites. A wide spatial distribution was observed for unipolar electrograms with a QS configuration around the successful ablation site. Mapping based on LAT and reversed polarity had a higher predictive value for a successful ablation site than mapping based on LAT and QS configuration., Conclusion: The presence of reversed polarity has a high predictive value for successful ablation sites in focal idiopathic RVOT arrhythmias and is likely to reduce the number of RFCA applications., (Copyright © 2011 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Objectives: The purpose of this study was to assess left atrial (LA) strain during long-term follow-up after catheter ablation for atrial fibrillation and to find predictors for LA reverse remodeling., Background: The association between LA reverse remodeling and improvement in LA strain after catheter ablation has not been investigated thus far., Methods: In 148 patients undergoing catheter ablation for atrial fibrillation, LA volumes and LA strain were assessed with echocardiography at baseline and after a mean of 13.2 ± 6.7 months of follow-up. The study population was divided according to LA reverse remodeling at follow-up: responders were defined as patients who exhibited 15% or more reduction in maximum LA volume at long-term follow-up. Left atrial systolic (LAs) strain was assessed with tissue Doppler imaging., Results: At follow-up, 93 patients (63%) were classified as responders, whereas 55 patients (37%) were nonresponders. At baseline, LAs strain was significantly higher in the responders as compared with the nonresponders (19 ± 8% vs. 14 ± 6%; p = 0.001). Among the responders, a significant increase in LAs strain was noted from baseline to follow-up (from 19 ± 8% to 22 ± 9%; p < 0.05), whereas no change was noted among the nonresponders. LAs strain at baseline was an independent predictor of LA reverse remodeling (odds ratio: 1.813; 95% confidence interval: 1.102 to 2.982; p = 0.019)., Conclusions: In the present study, 63% of the patients exhibited LA reverse remodeling after catheter ablation for atrial fibrillation, with a concomitant improvement in LA strain. LA strain at baseline was an independent predictor of LA reverse remodeling., (Copyright © 2011 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Multislice computed tomography (MSCT) is commonly acquired before radiofrequency catheter ablation (RFCA) for atrial fibrillation (AF) to plan and guide the procedure. MSCT allows accurate measurement of the left atrial (LA) and pulmonary vein (PV) dimensions and classification of the PV anatomy. The aim of the present study was to investigate the effect of LA dimensions, PV dimensions, and PV anatomy on the outcome of circumferential RFCA for AF. A total of 100 consecutive patients undergoing RFCA for AF (paroxysmal 72%, persistent 28%) were studied. The LA dimensions, PV dimensions, and PV anatomy were evaluated three dimensionally using MSCT. The PV anatomy was classified as normal or atypical according to the absence/presence of a common trunk or additional veins. After a mean follow-up of 11.6 ± 2.8 months, 65 patients (65%) maintained sinus rhythm. The enlargement of the left atrium in the anteroposterior direction on MSCT was related to a greater risk of AF recurrence. No relation was found between the PV dimensions and the outcome of RFCA. In addition, normal right-sided PV anatomy was related to a greater risk of AF recurrence compared to atypical right-sided PV anatomy. Multivariate analysis showed that an anteroposterior LA diameter on MSCT (odds ratio 1.083, p = 0.027) and normal right-sided PV anatomy (odds ratio 6.711, p = 0.006) were independent predictors of AF recurrence after RFCA. In conclusion, enlargement of the anteroposterior LA diameter and the presence of normal anatomy of the right PVs are independent risk factors for AF recurrence. No relation was found between the PV dimensions and outcome of RFCA., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Aims: Substrate-based ablation of ventricular tachycardia (VT) relies on electroanatomical voltage mapping (EAVM). Integration of scar information from contrast-enhanced magnetic resonance imaging (CE-MRI) with EAVM may provide supplementary information. This study assessed the relation between electrogram voltages and CE-MRI scar characteristics using real-time integration and reversed registration., Methods and Results: Fifteen patients without implantable cardiac defibrillator (14 males, 64 ± 9 years) referred for VT ablation after myocardial infarction underwent CE-MRI. Contours of the CE-MRI were used to create three-dimensional surface meshes of the left ventricle (LV), aortic root, and left main stem (LM). Real-time integration of CE-MRI-derived scar meshes with EAVM of the LV and aortic root was performed using the LM and the CARTO surface registration algorithm. Merging of CE-MRI meshes with EAVM was successful with a registration error of 3.8 ± 0.6 mm. After the procedure, voltage amplitudes of each mapping point were superimposed on the corresponding CE-MRI location using the reversed registration matrix. Infarcts on CE-MRI were categorized by transmurality and signal intensity. Local bipolar and unipolar voltages decreased with increasing scar transmurality and were influenced by scar heterogeneity. Ventricular tachycardia reentry circuit isthmus sites were correlated to CE-MRI scar location. In three patients, VT isthmus sites were located in scar areas not identified by EAVM., Conclusion: Integration of MRI-derived scar maps with EAVM during VT ablation is feasible and accurate. Contrast-enhanced magnetic resonance imaging identifies non-transmural scars and infarct grey zones not detected by EAVM according to the currently used voltage criteria and may provide important supplementary substrate information in selected patients.

Background: the presence of atrial fibrillation (AF) is related to increased levels of natriuretic peptides. In addition, increased natriuretic peptide levels are predictive of the development of AF. However, the role of natriuretic peptides to predict recurrence of AF after radiofrequency catheter ablation (RFCA) is controversial., Objective: the study aimed to investigate the role of natriuretic peptides in the prediction of AF recurrence after RFCA for AF., Methods: pre-procedural amino-terminal pro-atrial natriuretic peptide (NT-proANP) and amino-terminal-pro-B-type natriuretic peptide (NT-proBNP) plasma levels were determined in 87 patients undergoing RFCA for symptomatic drug-refractory AF. In addition, a comprehensive clinical and echocardiographic evaluation was performed at baseline. Left atrial volumes, left ventricular volumes, and function (systolic and diastolic) were assessed. During a 6-month follow-up period, AF recurrence was monitored and defined as any registration of AF on electrocardiogram or an episode of AF longer than 30 seconds on 24-hour Holter monitoring. The role of natriuretic peptide plasma levels to predict AF recurrence after RFCA was studied., Results: During follow-up, 66 patients (76%) maintained sinus rhythm, whereas 21 patients (24%) had AF recurrence. Patients with AF recurrence had higher baseline natriuretic peptide levels than patients who maintained sinus rhythm (NT-proANP 3.19 nmol/L [2.55-4.28] vs 2.52 nmol/L [1.69-3.55], P = .030; NT-proBNP 156.4 pg/mL [64.1-345.3] vs 84.6 pg/mL [43.3-142.7], P = .036). However, NT-proBNP was an independent predictor of AF recurrence, whereas NT-proANP was not. Moreover, NT-proBNP had an incremental value over echocardiographic characteristics to predict AF recurrence after RFCA., Conclusion: baseline NT-proBNP plasma level is an independent predictor of AF recurrence after RFCA.

Background: Improvement of left ventricular ejection fraction (LVEF) after radiofrequency catheter ablation (RFCA) of frequent premature ventricular contractions (PVCs) has been reported. However, most patients with frequent PVCs have a normal LVEF. In these patients subtle and early forms of PVC-induced left and right ventricular (RV) impairment may not be detected by standard echocardiographic techniques., Objective: To assess the effect of frequent PVCs on ventricular function in patients with preserved LVEF., Methods: 49 patients (30 male, 49+/-16 years) with recent-onset (median 1.2 years), frequent PVCs (burden 26+/-13%) and 25 healthy controls were studied. Thirty-four patients with PVCs underwent successful RFCA. Two-dimensional echocardiography was performed at baseline and follow-up. LV volumes and LVEF were calculated by Simpson's rule. Tricuspid annulus plane systolic excursion and fractional area change were calculated to assess RV function. Multidirectional LV strain (radial, circumferential, longitudinal) and RV free-wall longitudinal strain were calculated by two-dimensional speckle tracking imaging. At baseline LVEF, volumes and RV dimensions were normal in patients and controls., Results: Speckle tracking imaging demonstrated reduced LV and RV strain in patients with PVC as compared with controls. At follow-up there were no changes in LVEF, LV volumes and RV dimensions and function in patients successfully treated by RFCA and untreated patients. However, radial, circumferential and longitudinal strain improved significantly in patients after RFCA but remained unchanged in untreated patients., Conclusions: Frequent PVCs can induce subtle cardiac dysfunction detected by speckle tracking imaging analysis in patients without apparent cardiomyopathy. RFCA can successfully eliminate PVCs and improve cardiac function.

Background: Reperfusion therapy during acute myocardial infarction results in myocardial salvage and improved ventricular function but may also influence the arrhythmogenic substrate for ventricular tachycardia (VT). This study used electroanatomic mapping and infarct histology to assess the impact of reperfusion on the substrate and on VT characteristics late after acute myocardial infarction., Methods and Results: The study population consisted of 36 patients (32 men; age, 63+/-15 years) referred for treatment of VT 13+/-9 years after acute myocardial infarction. Fourteen patients with early reperfusion during acute myocardial infarction were compared with 22 nonreperfused patients. Spontaneous and induced VTs and the characteristics of electroanatomic voltage maps were analyzed. Twenty-seven patients were treated by radiofrequency catheter ablation. Ten patients (6 nonreperfused) were treated by ventricular restoration with intraoperative cryoablation in 9. During surgery, biopsies were obtained from the resected core of the infarct. VT cycle length of spontaneous and induced VTs was shorter in reperfused patients (reperfused, 299+/-52/270+/-58 ms; nonreperfused, 378+/-77/362+/-74 ms; P=0.01). An electroanatomic patchy scar pattern was present in 71% of reperfused and 14% of nonreperfused patients (P=0.004). The proportion of electroanatomic dense scar was smaller in reperfused patients (24+/-18% versus 45+/-21%; P=0.02). Histological assessment in 10 patients revealed thick layers of surviving myocardium in 75% of reperfused but in none of the nonreperfused patients., Conclusions: Scar size and pattern defined by electroanatomic mapping are different between VT patients with and without reperfusion during acute myocardial infarction. Less confluent electroanatomic scars match with thick layers of surviving myocardium on histology. Early reperfusion and less confluent electroanatomic scar are associated with faster VTs.

Background: Catheter ablation has evolved as a possible curative treatment modality for atrial tachyarrhythmia (AT) in patients with congenital heart defects (CHD). However, data on long-term outcome are scarce. We examined characteristics of recurrent AT after ablation of postoperative AT during long-term follow-up in CHD patients., Methods and Results: CHD patients (n=53; 27 men; age, 38+/-15 years) referred for catheter ablation of AT were studied during a follow-up period of 5+/-3 years. After ablative therapy of the first AT (n=53, 27 atrial flutter, cycle length=288+/-81 ms; 22 intra-atrial reentrant tachycardia, cycle length=309+/-81 ms; 5 focal atrial tachycardia, cycle length=380+/-147 ms; success rate, 65%), AT recurred (59% within the first year) in 29 patients; 15 underwent repetitive ablative therapy. Mechanisms underlying recurrent AT were similar in 7 patients (intra-atrial reentrant tachycardia, 2; atrial flutter, 5). The location of arrhythmogenic substrates of recurrent AT (intra-atrial reentrant tachycardia, focal atrial tachycardia) was different for all but 1 patient. After 5+/-3 years, 5 patients died of heart failure, 3 were lost to follow-up, and the remaining patients had sinus rhythm (n=31), AT (n=5), or atrial flutter (n=14). Antiarrhythmic drugs were used by 18 (57%) sinus rhythm patients., Conclusions: Successive postoperative AT in CHD patients developing over time may be caused by different mechanisms, including focal and reentrant mechanisms. Recurrent AT originated from different locations, suggesting that these new AT were not caused by arrhythmogenicity of previous ablative lesions. Long-term outcome is often complicated by development of atrial fibrillation. Despite frequent need for repeat ablative therapy, most patients are in sinus rhythm.

Atrial fibrillation (AF) is the most common cardiac arrhythmia, and is associated with an increased risk of cardiac morbidity and mortality. In this review, the role of multimodality imaging in the evaluation and treatment of AF is discussed in two main parts. First, an overview of the initial assessment of an AF patient is provided, including the role of different imaging techniques. Conditions that are associated with AF (coronary artery disease, heart failure, valvular heart disease, and left ventricular hypertrophy), and the assessment with various imaging modalities, will be reviewed. Furthermore, left atrial size assessment and the screening for thrombus formation are addressed. Secondly, the role of imaging in the invasive treatment of AF with catheter ablation is reviewed. Issues that should be considered before the procedure including contra-indications and pulmonary vein and left atrial anatomy will be discussed. Furthermore, the integration of different imaging modalities during catheter ablation is explored. Finally, an overview of the role of imaging in the follow-up of patients treated with catheter ablation will be provided.

Background: Catheter ablation has evolved as a possible curative treatment modality for supraventricular tachycardias (SVT) in patients with univentricular heart. However, the long-term outcome of ablation procedures is unknown. We evaluated the procedural and long-term outcome of ablative therapy of late postoperative SVT in patients with univentricular heart., Methods and Results: Patients with univentricular heart (n=19, 11 male; age, 29+/-9 years) referred for ablation of SVT were studied. Ablation was guided by 3D electroanatomic mapping in all but 2 procedures. A total of 41 SVT were diagnosed as intra-atrial reentrant tachycardia (n=30; cycle length, 310+/-68 ms), typical atrial flutter (n=4; cycle length, 288+/-42 ms), focal atrial tachycardia (n=6; cycle length, 400+/-60 ms), and atrial fibrillation (n=1). Ablation was successful in 73% of intra-atrial reentrant tachycardia, 75% of atrial flutter, and all focal atrial tachycardia and focal atrial fibrillation. During the follow-up period of 53+/-34 months, 2 patients were lost to follow-up, 3 died of heart failure, 2 underwent heart transplantation, and 1 underwent conduit replacement. Of the remaining group, 8 had sinus rhythm and 3 had SVT., Conclusions: Focal and reentrant mechanisms underlie postoperative SVT in patients with univentricular heart. Successive SVT developing over time may be caused by different mechanisms. Ablative therapy is potentially curative, with a procedural success rate of 78%. In patients who had multiple ablation procedures, the SVT originated from different atrial sites, suggesting that these new SVT were caused by progressive atrial disease. Despite recurrent SVT, sinus rhythm at the end of the follow-up period was achieved in 72%.

Background: The effect of successful catheter ablation on left ventricular (LV) strain in patients with preserved LV systolic function is unknown. The aim of the present study was to assess the long-term effects of catheter ablation for atrial fibrillation (AF) on LV strain and strain rate in patients with preserved LV ejection fraction., Methods and Results: In 78 patients undergoing catheter ablation for AF, speckle tracking strain imaging was performed to assess LV strain in 3 directions (radial, circumferential, and longitudinal) at baseline and after 12-month follow-up. The study population was divided into 2 groups, according to the maintenance of sinus rhythm (SR) during follow-up. After 13.8+/-4.7 months of follow-up, 54 patients (69%) were in SR (SR group), whereas 24 patients (31%) had recurrence of AF (AF group). No significant changes in LV ejection fraction from baseline to follow-up were noted (60+/-7% versus 59+/-7%, P=NS). Circumferential strain improved significantly in the SR group (-18.3+/-3.2% versus -20.4+/-3.8%, P<0.001), whereas it remained unchanged in the AF group (-18.9+/-3.5% versus -17.9+/-3.1%, P=NS). In the SR group, significant improvements in LV longitudinal strain and strain rate were noted, whereas in the AF group, LV longitudinal strain and strain rate deteriorated significantly at long-term follow-up., Conclusions: After successful catheter ablation, LV circumferential and longitudinal strain and strain rate improve significantly in patients who maintain SR. In contrast, a decrease in LV longitudinal strain and strain rate is observed in patients with recurrence of AF.

Background: Multislice computed tomography (MSCT) integration is commonly used to guide radiofrequency catheter ablation (RFCA) for atrial fibrillation (AF). MSCT provides detailed anatomical information but lacks the ability to provide real-time anatomy during RFCA. Intracardiac echocardiography (ICE) allows real-time visualization of cardiac structures., Objective: The purpose of this study was to investigate the feasibility of three-dimensional (3D) anatomical mapping of the left atrium (LA) with ICE and integrating the 3D map with MSCT to facilitate RFCA for AF., Methods: In 17 patients undergoing RFCA for AF, 3D mapping of the LA was performed with ICE using a new mapping system that allows tracking of a new ICE probe. On each ICE image, endocardial contours were traced and used to generate a 3D map of the LA and pulmonary veins (PVs). A preprocedurally acquired MSCT image of the LA was then integrated with the 3D map. Additionally, PV assessment with ICE was compared with MSCT., Results: Accurate 3D mapping could be performed in all patients with a mean number of 31.1 +/- 8.5 contours. Integration with MSCT resulted in a mean distance between the MSCT and ICE contours of 2.2 +/- 0.3 mm for the LA and PVs together and of 1.7 +/- 0.2 mm around the PV ostia specifically. Agreement in the assessment of PV anatomy and diameters between ICE and MSCT was excellent., Conclusion: Three-dimensional ICE mapping of the LA is feasible. The 3D map created with ICE can be merged with MSCT to facilitate RFCA for AF.

Real-time 3-dimensional echocardiography (RT3DE) can provide a unique combination of accurate left atrial (LA) volume quantification and rapid, automatic assessment of LA function. The aim of the study was to evaluate the changes in LA volumes and function in patients with atrial fibrillation (AF) undergoing radiofrequency catheter ablation (RFCA) using RT3DE; 57 consecutive patients referred for RFCA were studied. Paroxysmal AF was present in 43 patients (75%) and persistent AF in 14 (25%). After a mean follow-up of 7.9 +/- 2.7 months, patients were divided into 2 groups: successful RFCA (SR group) and recurrence of AF (AF group). RT3DE was performed before, within 3 days, and 3 months after RFCA to assess LA volumes (maximum, minimum, and preA) and LA functions (passive, active, and reservoir). A total of 38 patients (67%) had successful RFCA (SR group). Immediately after RFCA, no significant changes in LA volumes and function were observed. After 3 months, a significant reduction in LA volumes (maximum: 26 +/- 8 to 23 +/- 7 ml/m(2), p <0.01) was noted only in the SR group, with a significant improvement in LA active (22 +/- 8% to 33 +/- 9%, p <0.01) and reservoir functions (116 +/- 45% to 152 +/- 54%, p <0.01). Conversely, the AF group showed a trend towards a deterioration of LA volumes and function. In conclusion, in patients who maintain sinus rhythm after RFCA, a significant reverse remodeling and functional improvement of the left atrium is observed using RT3DE.

Background: Catheter ablation of ventricular tachycardia (VT) after repair of congenital heart disease can be difficult because of nonmappable VTs and complex anatomy. Insights into the relation between anatomic isthmuses identified by delineating unexcitable tissue using substrate mapping techniques and critical reentry circuit isthmuses might facilitate ablation., Methods and Results: Sinus rhythm voltage mapping of the right ventricle was performed in 11 patients with sustained VT after repair of congenital heart disease. Unexcitable tissue from patch material, valve annulus, or dense fibrosis, identified from bipolar voltage (<0.5 mV) and pacing threshold (>10 mA), was defined as an anatomic isthmus boundary bordering 4 isthmuses between (1) the tricuspid annulus and scar/patch in the anterior right ventricular outflow, (2) the pulmonary annulus and right ventricular free wall scar/patch, (3) the pulmonary annulus and septal scar/patch, and (4) the septal scar/patch and tricuspid annulus. The reentry circuit isthmuses of all induced 15 VTs (mean cycle length, 276+/-78 ms; 73% poorly tolerated), identified by activation, entrainment, and/or pace mapping, were located in an anatomic isthmus (11 of 15 VTs in anatomic isthmus 1). Transecting the anatomic isthmuses by ablation lesions abolished all VTs. During 30.4+/-29.3 months of follow-up, 91% of patients remained free of VT., Conclusions: Reentry circuit isthmuses in VT late after repair of congenital heart disease are located within anatomically defined isthmuses bordered by unexcitable tissue. The boundaries can be identified with 3-dimensional substrate mapping and connected by ablation lines during sinus rhythm. These findings should facilitate catheter and surgical ablation of stable and unstable VTs.

Objectives: This study was designed to assess the effects of long-term right ventricular (RV) pacing on left ventricular (LV) dyssynchrony, LV function, and heart failure symptoms., Background: Atrioventricular (AV) node ablation and subsequent long-term RV pacing is a well-established treatment option in patients with atrial fibrillation (AF)., Methods: In 55 patients with drug-refractory AF, AV node ablation and implantation of a pacemaker was performed. At baseline and after a mean of 3.8 +/- 1.7 years, LV dyssynchrony (by M-mode echocardiography and tissue Doppler imaging), LV function, and volumes and functional status were assessed., Results: After long-term RV pacing, 27 patients (49%) had developed LV dyssynchrony. Concomitantly, these patients worsened in heart failure symptoms (New York Heart Association functional class increased from 1.8 +/- 0.6 to 2.2 +/- 0.7, p < 0.05), with a decrease in LV ejection fraction (from 48 +/- 7% to 43 +/- 7%, p < 0.05) and an increase in LV end-diastolic volume (from 116 +/- 39 ml to 130 +/- 52 ml, p < 0.05). Conversely, patients without LV dyssynchrony did not deteriorate in heart failure symptoms, LV function, or LV volumes., Conclusions: Long-term RV pacing can induce LV dyssynchrony in almost 50% of patients treated with AV node ablation for chronic AF. The development of LV dyssynchrony was associated with deterioration in heart failure symptoms, systolic LV function, and LV dilatation.

Background: In patients late after surgical repair of congenital heart disease (CHD), areas with abnormal electrophysiologic properties may serve as slow conducting pathways within a macroreentrant circuit or may be the source of focal atrial tachycardia., Objectives: The purpose of this study was to evaluate the role of abnormal areas during focal atrial tachycardia prior to ablation., Methods: Electroanatomic activation mapping of 62 atrial tachycardias was performed in 43 consecutive patients (37 +/- 12 years) after surgical repair of CHD. The mechanism of atrial tachycardia was scar related intra-atrial reentry (n = 27), cavotricuspid-related atrial flutter (n = 21), atrial fibrillation (n = 2), or focal atrial tachycardia (n = 10). During intra-atrial reentry, channels of slow conduction could be identified in all patients. Subsequent ablation was directed toward connecting two nonconductive borders. The site of origin during focal atrial tachycardia showed fractionated potentials and/or continuous electrical activity., Results: Ablation directed at isolating the source area resulted in termination of focal atrial tachycardia in all cases. In two patients, ablation of an area showing continuous electrical activity giving rise to fibrillatory conduction resulted in termination of atrial fibrillation. Ablation of intra-atrial reentry was successful in 70%. Atrial flutter and focal atrial tachycardia were successfully ablated in all patients. No complications were observed., Conclusion: In patients with surgically corrected CHD, atrial tachycardia most often is caused by a macroreentrant mechanism but in some is the result of a focal mechanism. Areas of abnormal conduction may serve not only as a zone of slow conduction within a macroreentrant circuit but also as the site of origin of a focal atrial arrhythmia. Catheter ablation directed at "source isolation" is effective in eliminating focal atrial tachycardia in patients with CHD.

Left atrial (LA) remodeling is associated with atrial fibrillation (AF). Radiofrequency catheter ablation offers a good treatment option for AF, with reasonable long-term results. The purpose of the present study was to assess whether LA reverse remodeling occurs after successful catheter ablation. Fifty-seven consecutive patients (45 men; age 53 +/- 8 years) with symptomatic drug-refractory AF were treated with radiofrequency catheter ablation. The patients were divided into 2 groups on the basis of AF recurrence as determined by Holter monitoring and 12-lead electrocardiographic findings at 6 weeks and 3 months of follow-up (sinus rhythm [SR] group, no recurrence; AF group, AF recurrence). At baseline and 3 months of follow-up, 2-dimensional echocardiography was performed to assess LA size and dimensions. Furthermore, LA volumes were measured at end-systole and end-diastole. After 3 months, 39 of 57 patients (68%) maintained SR. At 3 months of follow-up, the LA anteroposterior diameter showed a significant reduction in the SR group (4.5+/- 0.3 vs 4.2 +/- 0.2 cm, p <0.01), and an additional increase was observed in the AF group (4.5+/- 0.3 vs 4.8 +/- 0.3 cm, p <0.05). Furthermore, the LA end-systolic and end-diastolic volumes decreased significantly in the SR group from baseline to follow-up (59 +/- 12 vs 50 +/- 11 ml, p <0.01, and 37 +/- 9 vs 31 +/- 7 ml, p <0.01, respectively). However, a tendency toward an increase in LA volumes was observed in the AF group. In conclusion, the results of this study have demonstrated that LA reverse remodeling occurs after successful radiofrequency catheter ablation for AF.

Introduction: Ablation of atrial tachycardia (AT) occurring late after cardiac surgery for congenital heart disease can be challenging due to the complexity of the arrhythmogenic substrate., Methods and Results: We performed an ablation procedure in a Fontan patient with an AT using a new approach combining 3D electroanatomical mapping with multislice computed tomography (MSCT). This technique visualizes the position of the catheter in relation to the endocardium, thereby improving delineation of scar tissue. The AT had a focal origin located between areas of scar tissue and was successfully ablated at the earliest activated site., Conclusion: Ablation of complex arrhythmias can be facilitated by fusion of electroanatomical map and MSCT.

Background: The outcome of catheter ablation procedures of cardiac arrhythmias depends on the ability to evaluate the underlying mechanism and to depict target sites for ablation. Fusion of different imaging modalities within one system may improve electroanatomic modeling and facilitate ablation procedures., Objectives: The purpose of this study was to study the feasibility of fusion of multislice computed tomography (MSCT) with electroanatomic mapping to guide radiofrequency catheter ablation of atrial arrhythmias., Methods: Sixteen patients (15 men, age 54 +/- 7 years) with drug-refractory atrial fibrillation (AF) underwent 64-slice MSCT within 2 days before radiofrequency catheter ablation. MSCT data were imported to the Carto electroanatomic mapping system. Using the new CartoMerge Image Integration Module, the MSCT images and the electroanatomic map were aligned. A statistical algorithm provided information about the accuracy of the fusion process., Results: In all patients, MSCT images could be fused with the electroanatomic map. Mean distance between the mapping points and the MSCT surface ranged from 1.7 +/- 1.2 mm to 2.8 +/- 1.8 mm. This resulted in an average of 2.1 +/- 0.2 mm for the patient group as a whole., Conclusion: MSCT images can be fused with the three-dimensional electroanatomic mapping system in an accurate manner. Anatomy-based catheter ablation procedures for atrial arrhythmias may be facilitated by integration of different imaging modalities.

Background: Zones of slow conduction facilitate reentry, the major mechanism of ventricular tachycardia (VT) after myocardial infarction (MI). Identification of these zones during sinus rhythm (SR) is desirable for radiofrequency (RF) catheter ablation of VT. Local conduction velocity may correlate with electrogram duration., Objectives: The purpose of this study was to revise the definition of normal electrogram characteristics and to reevaluate the significance of low-amplitude, long-duration electrograms recorded during SR to select RF catheter ablation sites in patients with VT., Methods: Electroanatomic mapping was performed during SR in 10 control patients with normal left ventricles (LVs) and in 10 patients with stable VT after MI. From the controls, reference values for electrogram amplitude, duration (first peak to last peak distance), and fragmentation (positive deflection) were derived. In patients after MI, areas with signals exceeding these values were annotated and related to successful ablation sites., Results: Ninety-five percent of normal LV electrograms were > or =1.0 mV and < or =28 ms (range 5-39 ms) and all had < or =4 deflections. Based on these results, cutoff values were set at 1 mV, four deflections, and 40 ms. In infarcted hearts, 653 electrograms (44%) were <1.0 mV and of these, 303 were > or =40 ms with >4 deflections and restricted to circumscribed areas. Twenty-seven of 28 targeted VTs remained noninducible after RF catheter ablation within these areas, resulting in 86% sensitivity and 94% specificity for low-amplitude, long-duration electrograms predicting successful ablation sites., Conclusion: Identification of successful RF target areas during SR in patients with VT is feasible with high sensitivity and specificity using a mapping strategy based on voltage and duration criteria.

Unlabelled: A premature neonate with hydrops was born at 32 weeks of gestation after successful direct fetal amiodarone therapy via cordocentesis for incessant supraventricular tachycardia. After birth the tachycardia could not be controlled despite high doses of amiodarone and flecainide and the patient developed severe respiratory and circulatory failure. After 3 weeks, weighing 2 kg, he underwent successful and uncomplicated catheter ablation of a left free-wall accessory pathway using low-energy radiofrequency., Conclusion: radiofrequency catheter ablation is rarely used in neonates, but when used with caution may provide the optimal treatment.