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Background: Coronary chronic total occlusion (CTO) can result in ischemic cardiomyopathy which may create substrate supportive of ventricular arrhythmias (VA). The purpose of this meta-analysis is to evaluate the association of CTOs with risk of ventricular arrhythmias (VAs) and to assess the utility of CTO percutaneous coronary intervention (PCI) in this setting., Methods: A literature search was conducted for studies reporting an association between CTOs and VAs and PCI VAs among patients with CTO. VAs were defined as ventricular tachycardia, ventricular fibrillation, sudden cardiac death, and appropriate implantable cardiac defibrillator therapy. The search included the following databases: Ovid MEDLINE, EMBASE, Web of Science, and Google Scholar. The search was not restricted to time or publication status., Results: Nine studies with 3068 participants (1405 with CTOs and 1663 with coronary artery disease [CAD]) met inclusion criteria. CTOs were associated with significantly higher risk of VAs compared with patients with CAD without CTOs (OR 2.25, 95 % CI 1.92-2.64; p < 0.01). Three studies with 1830 patients with CTOs (970 revascularized, 860 on optimal medical therapy) met inclusion criteria for evaluating the association of CTO revascularization and VAs. CTO PCI was associated with a significantly lower risk of VAs compared with patients treated with optimal medical therapy., Conclusions: Patients with CTOs appear to have a higher burden of VAs compared with patients with CAD without CTOs. Revascularization of CTOs was found to be associated with significant reduction in risk of VAs, however additional high-quality studies are required to further evaluate this association., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Competing Interests: Disclosures The authors have no conflicts of interest to disclose.

Background: Ablation of premature ventricular complexes (PVCs) originating from the parahisian area is challenging. Late gadolinium-enhanced cardiac magnetic resonance (LGE-CMR) scar may influence procedural outcomes; the impact of cardiac scar on parahisian PVCs has not been described., Objective: The objective of this study was to examine the incidence and significance of LGE-CMR scarring in patients undergoing ablation for parahisian PVCs., Methods: Consecutive patients who underwent preprocedure LGE-CMR imaging and ablation of parahisian PVCs were included. Acute and long-term outcomes were examined., Results: Forty-eight patients were included (male, n = 37; age, 66 ± 10 years; ejection fraction, 50% ± 12%; preprocedure PVC burden, 21% ± 12%). Intramural LGE-CMR scar was present in 33 of 48 (69%) patients. Cryoablation was used in 9 patients; ablation in multiple chambers was required in 28 (58%) patients. The PVC site of origin (SOO) was intramural (n = 25 patients), left ventricular (n = 5), and right ventricular (n = 18). Patients with LGE-CMR scar were more likely to have intramural PVCs (64% vs 27%; P < .04) and to require ablation in multiple cardiac chambers (58% vs 13%; P < .02). Patients with intramural scar required longer duration of ablation delivery (31 ± 20 minutes vs 17 ± 8 minutes; P < .02). Acute procedural success was 69%; PVC burden on follow-up was 6% ± 9% and similar for those with and without scar., Conclusion: Ablation of parahisian PVCs often requires mapping and ablation of multiple cardiac chambers, with an intramural SOO identified in most patients. An intramural scar was associated with an intramural SOO of the PVCs requiring more extensive ablation procedures, with similar long-term outcomes compared with those without scar., Competing Interests: Disclosures The authors have no conflicts of interest to disclose., (Copyright © 2024 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Cardiovascular magnetic resonance (CMR) is a proven imaging modality for informing diagnosis and prognosis, guiding therapeutic decisions, and risk stratifying surgical intervention. Patients with a cardiac implantable electronic device (CIED) would be expected to derive particular benefit from CMR given high prevalence of cardiomyopathy and arrhythmia. While several guidelines have been published over the last 16 years, it is important to recognize that both the CIED and CMR technologies, as well as our knowledge in MR safety, have evolved rapidly during that period. Given increasing utilization of CIED over the past decades, there is an unmet need to establish a consensus statement that integrates latest evidence concerning MR safety and CIED and CMR technologies. While experienced centers currently perform CMR in CIED patients, broad availability of CMR in this population is lacking, partially due to limited availability of resources for programming devices and appropriate monitoring, but also related to knowledge gaps regarding the risk-benefit ratio of CMR in this growing population. To address the knowledge gaps, this SCMR Expert Consensus Statement integrates consensus guidelines, primary data, and opinions from experts across disparate fields towards the shared goal of informing evidenced-based decision-making regarding the risk-benefit ratio of CMR for patients with CIEDs., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Patients with arrhythmias originating from papillary muscles (PAPs) often have pleomorphic ventricular arrhythmias (PVAs) that can result in failed ablations. The mechanism of PVAs is unknown., Objective: The purpose of this study was to assess the prevalence and mechanisms of PVAs and the impact on outcomes in patients with focal left ventricular PAP ventricular arrhythmias (VAs)., Methods: The sites of origin (SOOs) of VAs in 43 consecutive patients referred for ablation of focal left ventricular PAP VAs were determined by activation and pacemapping. SOOs were classified as (1) unifocal generating a single VA morphology; (2) unifocal from a deeper-seated origin generating multiple VA morphologies; (3) unifocal located on a PAP branching site; (4) multifocal from a single or multiple PAPs generating multiple VA morphologies; and (5) multifocal from a PAP and a different anatomic source., Results: Most patients had multiple morphologies (n = 34 [79%]) and multiple mechanisms (79%) generating the different VA morphologies. Most of the patients with PVAs had multiple SOOs from a single or different PAPs (n = 23 [68%]), followed by patients with SOOs from PAP and non-PAP sites (n = 19 [56%]). In 13 patients (38%), single SOOs accounted for the observed PVAs. The frequent observation (n = 20) of changing QRS morphologies after radiofrequency energy delivery targeting a single VA suggests the presence of a deeper focus with changing sites of preferential conduction., Conclusion: VA pleomorphism in patients with PAP arrhythmias is most often due to premature ventricular complexes originating from different SOOs. The second most common cause is preferential conduction from a single SOO via PAP branching sites., Competing Interests: Disclosures The authors have no conflicts to disclose., (Copyright © 2023. Published by Elsevier Inc.)

Background: Ventricular arrhythmias (VAs) originating from papillary muscles (PAPs) can be challenging when targeted with catheter ablation. Reasons may include premature ventricular complex pleomorphism, structurally abnormal PAPs, or unusual origins of VAs from PAP-myocardial connections (PAP-MYCs)., Objective: The purpose of this study was to correlate PAP anatomy with mapping and ablation of PAP VAs., Methods: In a series of 43 consecutive patients with frequent PAP arrhythmias referred for ablation, the anatomy and structure of PAPs and VA origins were analyzed using multimodality imaging. Successful ablation sites were analyzed for location on the PAP body or a PAP-MYC., Results: In a total of 17 of 43 patients (40%), VAs originated from a PAP-MYC (in 5 of 17 patients, the PAP inserted into the mitral valve anulus); and in 41 patients, VAs originated from a PAP body. VAs from a PAP-MYC more often had delayed R-wave transition than did other PAP VAs (69% vs 28%; P < .001). Patients with failed procedures had more PAP-MYCs (24.8 ± 8 PAP-MYCs per patient vs 16 ± 7 PAP-MYCs per patient; P < .001)., Conclusion: Multimodality imaging identifies anatomic details of PAPs that facilitate mapping and ablation of VAs. In more than a third of patients with PAP VAs, VAs originate from connections between PAPs and the surrounding myocardium or between other PAPs. VA electrocardiographic morphologies are different when VAs originate from PAP-connection sites as compared with VAs originating from the PAP body., (Copyright © 2023. Published by Elsevier Inc.)

Background: Late gadolinium enhanced cardiac magnetic resonance (LGE-CMR) imaging may help identify radiofrequency ablation lesions, which have been poorly described in patients with nonischemic cardiomyopathy (NICM)., Objectives: The purpose of this study was to describe LGE-CMR characteristics of ablation lesions in patients with NICM and correlate them with histopathology., Methods: Twenty-six patients (24 men; ejection fraction 38% ± 14%; age 61 ± 9 years) who had undergone CMR imaging after ventricular tachycardia (VT) ablation were included. Areas of both dark and bright core lesions correlating with previous radiofrequency ablation lesions were identified. Histology was performed on an explanted heart., Results: Mean time between the ablation procedure and the LGE-CMR study was 8 [2-20] months. Twenty-three of 26 patients demonstrated dark core lesions (volume 2.16 ± 1.8 cm 3 ; thickness 3.6 ± 1.3 mm) with transmurality of 42% ± 16% overlaying areas of intramural or transmural LGE. Fourteen of 26 patients demonstrated bright core lesions (volume 0.8 ± 0.6 cm 3 ; depth 4.15 ± 1.76 mm) with transmurality of 34% ± 14%, which was located in areas without underlying LGE in 11 of 13 patients. Both dark and bright core lesions were visualized on standard clinical LGE-CMR imaging obtained in the acute setting and chronic settings (within 3 days and up to 2090 days postablation). Histopathologic analysis demonstrated coagulation necrosis in the area that corresponded to dark core lesions in the postablation CMR., Conclusion: Ablation lesions can be detected by LGE-CMR after VT ablation in NICM patients and have a different appearance than scar tissue. These lesions can be observed in the acute and chronic settings after ablations., (Copyright © 2022. Published by Elsevier Inc.)

Background: Cardiac sarcoidosis (CS) with right ventricular (RV) involvement can mimic arrhythmogenic right ventricular cardiomyopathy (ARVC). Histopathological differences may result in disease-specific RV activation patterns detectable on the 12-lead electrocardiogram. Dominant subepicardial scar in ARVC leads to delayed activation of areas with reduced voltages, translating into terminal activation delay and occasionally (epsilon) waves with a small amplitude. Conversely, patchy transmural RV scar in CS may lead to conduction block and therefore late activated areas with preserved voltages reflected as preserved R' waves., Objective: The purpose of this study was to evaluate the distinct terminal activation patterns in precordial leads V 1 through V 3 as a discriminator between CS and ARVC., Methods: Thirteen patients with CS affecting the RV and 23 patients with gene-positive ARVC referred for ventricular tachycardia ablation were retrospectively included in a multicenter approach. A non-ventricular-paced 12-lead surface electrocardiogram was analyzed for the presence and the surface area of the R' wave (any positive deflection from baseline after an S wave) in leads V 1 through V 3 ., Results: An R' wave in leads V 1 through V 3 was present in all patients with CS compared to 11 (48%) patients with ARVC (P = .002). An algorithm including a PR interval of ≥220 ms, the presence of an R' wave, and the surface area of the maximum R' wave in leads V 1 through V 3 of ≥1.65 mm 2 had 85% sensitivity and 96% specificity for diagnosing CS, validated in a second cohort (18 CS and 40 ARVC) with 83% sensitivity and 88% specificity., Conclusion: An easily applicable algorithm including PR prolongation and the surface area of the maximum R' wave in leads V 1 through V 3 of ≥1.65 mm 2 distinguishes CS from ARVC. This QRS terminal activation in precordial leads V 1 through V 3 may reflect disease-specific scar patterns., (Copyright © 2021 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Objectives: This study sought to describe cardiac magnetic resonance (CMR) characteristics of ablation lesions within post-infarction scar., Background: Chronic ablation lesions created during radiofrequency ablation of ventricular tachycardia (VT) in the setting of prior myocardial infarction have not been described in humans., Methods: Seventeen patients (15 men, ejection fraction 25 ± 8%, 66 ± 6 years of age) with CMR imaging prior to repeat ablation procedures for VT were studied. Electroanatomic maps from first-time procedures and subsequent CMR images were merged and retrospectively compared with electroanatomic maps from repeat procedures., Results: The delay between the index ablation procedure and the CMR study was 30 ± 29 months. Late gadolinium-enhanced CMR revealed a confluent nonenhancing subendocardial dark core within the infarct-related scar tissue in all patients. Intracardiac thrombi were ruled out by transthoracic and intracardiac echocardiography. These core lesions matched the distribution of prior ablation lesions, and corresponded to unexcitable areas at repeat procedures., Conclusions: Ablation lesions can be detected by CMR after VT ablation in post-infarction patients and have a different appearance than scar tissue. These lesions can be observed many months after an initial ablation., Competing Interests: Funding Support and Author Disclosures This research was supported by funding from the French National Research Agency under grant agreements Equipex MUSIC ANR-11-EQPX-0030 and IHU LIRYC ANR-10-IAHU-04, and from the European Research Council under grant agreement ERC n715093. The authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2021 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: Frequent premature ventricular complexes (PVCs) can result in PVC-induced cardiomyopathy (PICM). Scarring has been described in patients with frequent PVCs in the absence of apparent heart disease and in patients with known cardiomyopathy., Objective: The purpose of this study was to determine the impact of focal myocardial scarring as detected by cardiac magnetic resonance imaging (CMR) on PICM, procedural outcomes, and recovery of left ventricular function in patients with frequent PVCs., Methods: A total of 351 consecutive patients (181 men; age 53 ± 15 years; ejection fraction [EF] 51% ± 12%) with frequent PVCs referred for ablation were included. CMR was performed in all patients before the ablation procedure. A ≥10% increase in EF or normalization of a previously abnormal EF was defined as evidence of PICM., Results: Myocardial scarring was present in 134 of 351 patients (38%); 66 of 134 patients (49%) with scarring and 54 of 217 patients (25%) without scarring had improvement or normalization of EF after ablation. The presence of myocardial scarring, PVC burden >22%, male sex, asymptomatic status, and PVC QRS width >150 ms were associated with PICM by univariate analysis (P <.01 for all). The presence of scar was independently associated with PICM (odds ratio 2.2; 95% confidence interval 1.3-3.7; P <.005). The success rate of PVC ablation was lower in patients with scarring than in patients without focal scarring (mean 70% vs 82%; P <.01)., Conclusion: Focal scar defined by CMR is independently associated with PICM. Although ablation outcomes are worse in the presence of scarring, EF recovery can occur in most of these patients after ablation., (Copyright © 2020. Published by Elsevier Inc.)

Background: Patients with nonischemic cardiomyopathy (NICM) often require epicardial ventricular tachycardia (VT) ablation procedures via subxiphoid access. The coronary venous system (CVS) provides limited access to the epicardial space., Objective: The purpose of this study was to determine the value of an approach targeting the CVS in these patients., Methods: In a series of 41 consecutive patients (mean age 59.7 ± 11.5 years; 36 men [88%]; ejection fraction 34.5% ± 13.1%; 269 inducible VTs [6.6 ± 5.0 VTs per patient]) with NICM and VT, mapping and ablation were performed sequentially at the endocardium, then within the CVS, and finally within the pericardial space if required., Results: VT target sites were identified within the CVS in 15 patients and by subxiphoid access to the pericardial space in 8 patients. Ablation within the CVS eliminated VT inducibility in 9 patients without the need for epicardial ablation. Cardiac magnetic resonance imaging demonstrated that the CVS was closer to a scarred area in patients with CVS-related VT target sites than in other patients (mean 3.5 ± 3.9 mm vs 14.3 ± 8.3 mm; P < .001). A cutoff distance of ≤9 mm from the scar (area under the curve 0.91; 95% confidence interval 0.82-0.99; sensitivity 0.78; specificity 0.93) identified patients with vs patients without VT target sites within the CVS., Conclusion: A stepwise approach with mapping/ablation in the endocardium followed by ablation within the CVS can reduce the need for subxiphoid epicardial access in some patients with NICM. Proximity of the scar to the CVS detected by cardiac magnetic resonance imaging can identify the patients most likely to benefit from this approach., (Copyright © 2020. Published by Elsevier Inc.)

Background: Frequent premature ventricular complexes (PVCs) can be an indicator of structural heart disease., Objective: The purpose of this study was to determine the prevalence of scarring detected by delayed enhancement cardiac magnetic resonance (DE-CMR) imaging in patients with frequent PVCs without apparent structural heart disease and to determine the value of programmed ventricular stimulation (PVS) for risk stratification in patients with frequent PVCs and myocardial scarring., Methods: DE-CMR imaging was performed in patients without apparent heart disease who had frequent PVCs and were referred for ablation. In the presence of scarring, scar volume was measured and correlated with outcome variables. All patients underwent PVS and were monitored for the occurrence of ventricular arrhythmias. Logistic regression was used to compare imaging and procedural findings with long-term outcomes, with adjustment for postablation ejection fraction (EF)., Results: The study consisted of 272 patients (135 men; mean age 52 ± 15 years; EF 52% ± 12%). DE-CMR scar was found in 67 patients (25%), and 7 (3%) were found to have inducible ventricular tachycardia (VT). The presence and amount of DE-CMR were related to the risk of long-term VT independent of EF (hazard ratio 18.8 [95% confidence interval] [2.0-176.6], P = .01; and hazard ratio 1.4 [1.1-1.7] per cm 3 scar, P <.001, respectively). The positive predictive value and negative predictive value of PVS for VT during long-term follow-up were 71% and 100%, respectively., Conclusion: Preprocedural cardiac DE-CMR and PVS can be used to identify patients with frequent PVCs without apparent heart disease who are at risk for VT., (Copyright © 2019 Heart Rhythm Society. All rights reserved.)

Ventricular arrhythmias are an important cause of morbidity and mortality and come in a variety of forms, from single premature ventricular complexes to sustained ventricular tachycardia and fibrillation. Rapid developments have taken place over the past decade in our understanding of these arrhythmias and in our ability to diagnose and treat them. The field of catheter ablation has progressed with the development of new methods and tools, and with the publication of large clinical trials. Therefore, global cardiac electrophysiology professional societies undertook to outline recommendations and best practices for these procedures in a document that will update and replace the 2009 EHRA/HRS Expert Consensus on Catheter Ablation of Ventricular Arrhythmias. An expert writing group, after reviewing and discussing the literature, including a systematic review and meta-analysis published in conjunction with this document, and drawing on their own experience, drafted and voted on recommendations and summarized current knowledge and practice in the field. Each recommendation is presented in knowledge byte format and is accompanied by supportive text and references. Further sections provide a practical synopsis of the various techniques and of the specific ventricular arrhythmia sites and substrates encountered in the electrophysiology lab. The purpose of this document is to help electrophysiologists around the world to appropriately select patients for catheter ablation, to perform procedures in a safe and efficacious manner, and to provide follow-up and adjunctive care in order to obtain the best possible outcomes for patients with ventricular arrhythmias., (Copyright © 2019 The Heart Rhythm Society; the European Heart Rhythm Association, a registered branch of the European Society of Cardiology; the Asia Pacific Heart Rhythm Society; and the Latin American Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

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: In patients with implantable cardioverter-defibrillator (ICD), ventricular tachycardia (VT) can occur spontaneously or as a result of antitachycardia pacing (ATP) that changes, rather than terminates, a spontaneous VT to a different VT. The relevance of ATP-induced VTs is uncertain., Objective: The purpose of this study was to assess the clinical relevance of ATP-mediated VTs in patients undergoing VT ablation procedures., Methods: Stored ICD electrograms of 162 consecutive patients with prior myocardial infarction referred for VT ablation (mean age 67.5 ± 9.2 years; 150 men; median ejection fraction 25% [IQR 20%-35%]) were reviewed. Clinical VTs were classified as spontaneous or ATP-induced. All VTs were targeted during the ablation procedures., Results: Of 554 ICD-recorded clinical VTs, 157 (28%) were ATP-induced (63 patients) and 397 (72%) were spontaneous. ATP-induced VTs were faster (cycle length 316 ± 62 ms vs 369 ± 83 ms; P < .001), less commonly inducible with invasive programmed stimulation (35% vs 52%; P < .001), and less commonly had identifiable target sites (21% vs 40%; P < .001) than were spontaneous VTs. During a median follow-up of 368 days [IQR: 68-1106] postablation, 71 VTs recurred (39 patients), none of which was a previously documented ATP-induced VT. A history of ATP-induced VT was associated with an increase in VT recurrence., Conclusion: ATP-induced VTs occur frequently in patients with prior myocardial infarction presenting for VT ablation procedures. The presence of ATP-induced VT is associated with a higher VT recurrence rate postablation. None of the ATP-induced VTs recorded before the ablation procedure recurred postablation, and therefore ATP-induced VTs represent a marker rather than the cause of VT recurrence., (Copyright © 2018 Heart Rhythm Society. Published by Elsevier Inc. 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.)

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.)

Background: The role of the ligament of Marshall (LOM) in patients with atrial fibrillation (AF) has not been well defined., Objective: The purpose of this study was to describe the role of the LOM in patients with AF and related arrhythmias., Methods: Fifty-six patients (mean age 63 ± 11 years; persistent AF in 48 [86%]; ejection fraction 0.49 ± 0.13; left atrial diameter 4.7 ± 0.6 cm) with LOM-mediated arrhythmias were included., Results: A LOM-pulmonary vein (PV) connection was present in 18 patients (32%) and was eliminated with radiofrequency (RF) ablation at the left lateral ridge or crux (n = 12), at the mitral annulus (n = 3), or with alcohol/ethanol (EtOH) ablation of the vein of Marshall (VOM; n = 3). A LOM-mediated atrial tachycardia (AT) was present in 13 patients (23%). Thirty-one patients with refractory mitral isthmus conduction were referred for potential EtOH ablation. In the 6 patients in whom VOM was injected during perimitral reentry, EtOH resulted in slowing in 3 patients and termination in 1 patient. In others, EtOH infusion resulted in complete isolation of the left-sided PVs and left atrial appendage. Repeat RF and adjunctive EtOH ablation of the VOM tended to be more effective in creating conduction block across the mitral isthmus than RF ablation alone (P = .057)., Conclusion: The LOM is responsible for a variety of arrhythmia mechanisms in patients with AF and atrial tachycardia. It may be ablated at any point along its course, at the mitral annulus, at the lateral ridge/PV antrum, and epicardially in the coronary sinus and the VOM itself. EtOH ablation of the VOM may be an adjunctive strategy in patients with refractory perimitral reentry., (Copyright © 2017. Published by Elsevier 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: Premature ventricular complexes (PVCs) often originate from multiple locations., Objective: The goals of this study were to assess characteristics of patients with pleomorphic, idiopathic PVCs and to determine the impact of pleomorphic PVCs on outcomes., Methods: Records were collected from 153 consecutive patients referred for ablation of PVCs. Patients with structural heart disease (n = 34) or inadequate ambulatory electrocardiographic data (n = 19) were excluded., Results: Among 100 consecutive patients (age 52 ± 15 years, 53% men, 31% pleomorphic vs 69% monomorphic) referred for ablation of idiopathic PVCs, the success rate was lower in patients with pleomorphic PVCs than in those with monomorphic PVCs (71% vs 90%, P = .017, overall 84%). The presence of pleomorphic PVCs was independently associated with unsuccessful ablation. A cutoff of ≥156 nonpredominant PVCs over 24 hours best differentiated successful from unsuccessful ablation procedures (area under the curve 0.64, sensitivity 56%, specificity 74%). Pleomorphic PVCs more often had an epicardial origin than did monomorphic PVCs (29% vs 9%, P = .008). Repeat ablation procedures were required in 20 patients (20%; 6 had pleomorphic PVCs). Of these 20 patients, 16 (80%) had recurrence of the former predominant PVC, 3 patients (15%) had an increase of a nonpredominant PVC, and 1 patient (5%) had a newly emerging PVC focus., Conclusion: The presence of pleomorphic PVCs affects ablation outcomes. Successful elimination of the predominant PVC often results in successful ablation, even if not all PVCs are targeted. Although pleomorphic PVCs infrequently require repeat ablation procedures, most recurrences are due to reemergence of the originally targeted predominant PVC morphology., (Copyright © 2017 Heart Rhythm Society. All rights reserved.)

Background: Knowledge of complex arrhythmogenic substrates can help plan ventricular tachycardia (VT) ablation in patients with idiopathic dilated cardiomyopathy (DCM)., Objective: The purpose of this study was to assess whether preprocedural late gadolinium enhancement magnetic resonance imaging (LGE-MRI) can improve ablation outcomes in DCM., Methods: Consecutive patients (N = 96) with idiopathic DCM underwent VT ablation with open-irrigated catheters (2006-2016). Before 2012, LGE-MRI was not performed at our institution in patients with implanted devices, but it has been performed routinely in all patients after implementation of a new MRI protocol in 2012. We retrospectively compared acute and long-term outcomes of initial VT ablation procedures in patients with (n = 41) and those without (n = 55) preprocedural LGE-MRI. Procedural outcome was classified as successful if VT was not inducible postablation., Results: The 2 groups had a similar mean age and ejection fraction, comorbidities, and frequency of epicardial ablation. Preablation LGE-MRI was independently associated with improved procedural success (63% vs 24%) by logistic regression analysis (adjusted odds ratio [OR] 7.86, P <.001). This result was consistent even when patients with nondiagnostic MRIs due to artifact were included in the imaging group (OR 4.87, P = .005). Preablation imaging was also associated with improved survival free of the composite endpoint of VT recurrence, heart transplantation, or death, which was met by 11 (27%) and 33 (60%) patients in the imaging and no imaging groups, respectively, after median 7.6 months of follow-up (unadjusted log-rank P = .02). However, there was no association with long-term outcomes after adjustment for other covariates., Conclusion: Preprocedural imaging with LGE-MRI may be associated with improved outcomes of VT ablation in DCM., (Copyright © 2017 Heart Rhythm Society. All rights reserved.)

Recent advances in 3-dimensional electroanatomical mapping have been met by continuous improvements in the field of cardiac imaging and image integration during ablation procedures. Echocardiography, computed tomography, cardiac magnetic resonance, and nuclear imaging provide information about cardiac anatomy and ultrastructure of the heart that may be crucial for a successful ablation procedure. Techniques and value of pre-procedural, intraprocedural, and post-procedural imaging and image integration are discussed in this review article. Pre-procedural imaging provides key anatomic information that can be complemented by intraprocedural imaging to minimize procedural complications. Furthermore, the presence and extent of structural heart disease can be assessed pre-procedurally and can be displayed intraprocedurally to limit and focus the mapping and ablation procedure to the area of interest. Pre-procedural imaging combined with imaging obtained during the ablation procedure further enhances procedural safety, reduces exposure to ionizing radiation from fluoroscopy, reduces procedure time, and may improve outcomes., (Copyright © 2016 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: Adenosine can reveal dormant pulmonary vein (PV) conduction after PV isolation (PVI) in patients with paroxysmal atrial fibrillation (AF). However, the impact of elimination of adenosine-provoked dormant PV conduction after PVI has not been formally evaluated., Objective: The purpose of this study was to determine whether ablation of PV reconnections unmasked by adenosine improves outcomes., Methods: Patients with paroxysmal AF (n = 129) were randomized to receive either adenosine (n = 61) or no adenosine (n = 68) after PVI. Dormant conduction revealed by adenosine after PVI was ablated until all adenosine-mediated reconnections were eliminated. Thereafter, both groups received isoproterenol., Results: Acute reconnection was seen in 23 patients (37%) in the adenosine group. There was a significant difference between the number of PVs reconnected if patients were given adenosine >60 minutes after initial PVI compared to those who received adenosine <60 minutes after initial PVI (3/32 [9.4%] vs 24/32 [75%], P <.0001). Patients who did not receive adenosine had more PV reconnections after isoproterenol infusion compared to patients in the adenosine group (17/68 [25.0%] vs 5/61 [8.2%], P = .018). There was no difference in the rate of AF recurrence in patients who received adenosine (24/61 [39%]) compared to control patients (23/68 [34%], log-rank P = .83)., Conclusion: Adenosine can reveal dormant conduction in more than one-third of patients with paroxysmal AF undergoing PVI. However, adenosine administration, and additional ablation of the resultant connections, does not improve long-term outcomes compared to a protocol that includes isoproterenol infusion., (Copyright © 2016 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: The failure to identify a successful target site for catheter ablation despite extensive endocardial and epicardial mapping is a common feature for an intramural site of origin of a ventricular arrhythmia., Objective: The purpose of this study was to assess whether transient suppression of premature ventricular complexes (PVCs) by injection of cold saline into the distal coronary venous system can identify an intramural focus., Methods: Cold saline (room temperature) was injected through an irrigated-tip catheter into the distal coronary venous system in a consecutive series of 26 patients with frequent PVCs referred for catheter ablation., Results: PVCs were temporarily suppressed in 11 of 26 patients during injection of cold saline. Extensive mapping suggested the presence of an intramural site of origin in 9 of 11 patients with PVC suppression by cold saline but in only 1 of 15 patients in whom PVCs were not suppressed. The suppression of PVCs by cold saline was associated with the presence of an intramural PVC focus with an accuracy of 88% (sensitivity 90%, specificity 88%, positive predictive value 82%, negative predictive value 93%, P = .0002)., Conclusion: Temporary suppression of PVCs by cold saline infused into the distal coronary venous system and the perforator veins strongly suggests the presence of an intramural septal focus of the PVCs., (Copyright © 2016 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Frequent idiopathic premature ventricular complexes (PVCs) can result in a reversible form of cardiomyopathy., Objective: The purpose of this study was to assess the impact of variability in PVC frequency throughout the day on PVC-induced cardiomyopathy., Methods: The subjects of this study were 107 consecutive patients (58 men [54%]; mean age 49.7 ± 15.0 years; left ventricular ejection fraction 50.4% ± 11.4%) referred for ablation of frequent PVCs. All patients underwent 24-hour Holter monitoring before the ablation procedure. The circadian variation in PVC burden was determined and correlated with the presence or absence of cardiomyopathy., Results: A total of 43 patients (40%) had cardiomyopathy. Patients with cardiomyopathy had an ejection fraction of 38.4% ± 6.9%, a higher PVC burden (28.5% ± 11.5% vs 19.5% ± 10.5%; P = .0001), less variability in circadian PVC distribution (coefficient of variation hourly: 31.5% ± 21% vs 59.8% ± 32.4%; P = .0001), and more frequent interpolated PVCs (20 patients [47%] vs 15 patients [23%]; P = 0.022), and were more frequently asymptomatic than patients without cardiomyopathy (56% vs 19%; P = .0001). In multivariate analysis, consistency in PVC burden throughout the day was an independent predictor of PVC-induced cardiomyopathy (odds ratio 16.3; 95% confidence interval 1.7-155.3; p = 0.015)., Conclusion: In patients with frequent PVCs, consistency in hourly PVC frequency throughout the day is an independent predictor of PVC-induced cardiomyopathy., (Copyright © 2016 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Pace mapping (PM) is used to identify the origin of ventricular arrhythmias (VAs). For intramural VAs, the site of origin often cannot be reached and therefore PM is less accurate., Objective: The purpose of this study was to assess the value of single- and dual-site pace maps to differentiate intramural from nonintramural VAs., Methods: In 18 consecutive patients with idiopathic intramural VAs, pace mapping was performed at 2 breakthrough sites in adjacent anatomic structures. Twelve-lead electrocardiograms of the 2 pace maps were averaged in MATLAB and compared (correlation coefficient [CC]) with the targeted VA. Dual-site pace mapping was performed in a control group of 18 patients with nonintramural VAs at the sites of earliest electrical activation and a breakthrough site in an adjacent anatomic location., Results: Dual-site pace maps had a higher CC than did best single-site pace maps (0.87 ± 0.1 vs 0.81 ± 0.16; P = .02) in patients with intramural VAs. At the site of origin, single-site pace maps had a higher CC than did dual-site pace maps obtained from adjacent anatomic locations (0.93 ± 0.04 vs 0.89 ± 0.05; P = .0004) in patients with nonintramural VAs. Sensitivity, specificity, positive predictive value, and negative predictive value of dual-site pace maps for identifying an intramural VA were 89%, 82%, 84%, 88%, and 86%, respectively. Furthermore, the receiver operating characteristic curve analysis revealed that a CC cutoff value of ≤0.86 for a single-site pace map best differentiated intramural from nonintramural VAs., Conclusion: A higher CC value for a dual-site pace map obtained from the earliest breakthrough site as well as a CC cutoff value of ≤0.86 for a single-site pace map obtained from the site of earliest electrical activation can best differentiate intramural from nonintramural VAs., (Copyright © 2016 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Presentation, prognosis, and management of premature ventricular complexes (PVCs) vary significantly among patients and depend on PVC characteristics as well as patient comorbidities. Presentation can range from incidental discovery in an asymptomatic patient to debilitating heart failure. Prognosis depends on, among other factors, the presence or absence of structural heart disease, PVC burden and other factors detailed in this review. Our understanding of the clinical significance of frequent PVCs, particularly as it relates to development of cardiomyopathy, has advanced greatly in the past decade. In this article, we explore the mechanisms governing PVC initiation and discuss prevalence and frequency of PVCs in the general population. We also explore prognostic implications based on PVC frequency as well as the presence or absence of underlying heart disease. We then take a focused look at PVC-induced cardiomyopathy and identify predictors for developing cardiomyopathy. Finally, we discuss clinical evaluation and management of patients presenting with frequent PVCs. Management can include clinical observation, addressing reversible causes, lifestyle modification, pharmacotherapy, or catheter ablation., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Background: The natural history of premature ventricular complex (PVC)-induced cardiomyopathy is incompletely understood., Objective: The purpose of this study was to assess long term follow-up data in patients who underwent successful PVC ablation for PVC-induced cardiomyopathy., Methods: The subjects of this study were 60 patients (17 women; mean age 52.5 ± 16.8 years; ejection fraction [EF] 37.3 ± 8.5%, median 40%, interquartile range [IQR] 15) with PVC-induced cardiomyopathy who underwent successful ablation of their predominant PVCs between 2005 and 2012. Patients were followed up for a mean of 23.6 ± 17.2 months. EF improved to 57.2 ± 4.7% (median 55%, IQR 5; P = .0001) within 9.6 ± 8.4 months of the ablation procedure. During follow-up, 10 of 60 patients (16.7%) had recurrent frequent PVCs and 50 patients (83.3%) did not. Patients underwent repeat assessment of EF and PVC burden., Results: During follow-up of 23.6 ± 17.2 months, 10 patients had recurrent frequent PVCs, with an increase of their PVC burden from 1.4 ± 0.9% (median 1.05%, IQR 1.59) after the initial ablation to 27.2 ± 8.8% (median 26.0%, IQR 18.2; P = .018). Their EF decreased from 55.7 ± 3.4% (median 55%, IQR 5.8) after the initial ablation to 40.2 ± 5.1% (median 40%, IQR 15; P = .005). In the remaining patients with PVC-induced cardiomyopathy, EF and PVC burden remained unchanged during follow-up. Patients with PVC recurrence had a higher number of pleomorphic PVC morphologies during initial presentation (4.7 ± 2.2 vs 2.5 ± 2.8, P = .002)., Conclusion: Recurrence of frequent PVCs in patients with a history of PVC cardiomyopathy can result in recurrence of cardiomyopathy. Follow-up in patients with PVC-induced cardiomyopathy is important, especially if patients were asymptomatic from the PVCs and have pleomorphic PVCs., (Copyright © 2015 Heart Rhythm Society. Published by Elsevier Inc. 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: Twelve-lead electrocardiogram (ECG) criteria for epicardial ventricular tachycardia (VT) origins have been described. In patients with structural heart disease, the ability to predict an epicardial origin based on QRS morphology is limited and has been investigated only for limited regions in the heart., Objective: The purpose of this study was to determine whether a computerized algorithm is able to accurately differentiate epicardial vs endocardial origins of ventricular arrhythmias., Methods: Endocardial and epicardial pace-mapping were performed in 43 patients at 3277 sites. The 12-lead ECGs were digitized and analyzed using a mixture of gaussian model (MoG) to assess whether the algorithm was able to identify an epicardial vs endocardial origin of the paced rhythm. The MoG computerized algorithm was compared to algorithms published in prior reports., Results: The computerized algorithm correctly differentiated epicardial vs endocardial pacing sites for 80% of the sites compared to an accuracy of 42% to 66% of other described criteria. The accuracy was higher in patients without structural heart disease than in those with structural heart disease (94% vs 80%, P = .0004) and for right bundle branch block (82%) compared to left bundle branch block morphologies (79%, P = .001). Validation studies showed the accuracy for VT exit sites to be 84%., Conclusion: A computerized algorithm was able to accurately differentiate the majority of epicardial vs endocardial pace-mapping sites. The algorithm is not region specific and performed best in patients without structural heart disease and with VTs having a right bundle branch block morphology., (Copyright © 2014 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 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: Radiation therapy's (RT's) effects on cardiac implantable electronic devices (CIEDs) such as implantable cardioverter-defibrillators (ICDs) and pacemakers (PMs) are not well established, leading to device removal or relocation in preparation for RT., Objective: To determine the effect of scattered RT on CIED performance., Methods: We analyzed 69 patients--50 (72%) with PMs and 19 (28%) with ICDs--receiving RT at the University of Michigan. Collected data included device model, anatomic location, and treatment beam energies, treatment type, and estimated dose to the device. Patients were treated with either high-energy (16-MV) and/or low-energy (6 MV) photon beams with or without electron beams (6-16 MeV). The devices were interrogated with pre- and post-RT and/or weekly with either in-treatment or home interrogation, depending on the patient's dependence on the device and the estimated or measured delivered dose. Outcomes analyzed were inappropriate ICD therapies, device malfunctions, or device-related clinical events., Results: The PMs were exposed to 84.4 ± 99.7 cGy of radiation, and the ICDs were exposed to 92.1 ± 72.6 cGy of radiation. Two patients with ICDs experienced a partial reset of the ICD with the loss of historic diagnostic data after receiving 123 and 4 cGy, respectively. No device malfunction or premature battery depletion was observed at 6-month follow-up from RT completion., Conclusions: CIED malfunction due to indirect RT exposure is uncommon. Regular in-treatment or home interrogation should be done to detect and treat these events and to ensure that diagnostic data are preserved., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Background: Patients with frequent premature ventricular complexes (PVCs) are at risk of developing reversible PVC-induced cardiomyopathy (rPVC-CMP). Not all determinants of rPVC-CMP are known., Objective: To assess the impact of the QRS duration of PVCs on the development of rPVC-CMP., Methods: In a consecutive series of 294 patients with frequent idiopathic PVCs referred for PVC ablation, the width of the PVC-QRS complex was assessed. The QRS width was correlated with the presence of rPVC-CMP., Results: The PVC-QRS width was significantly greater in patients with rPVC-CMP than in patients without rPVC-CMP (164 ± 20 ms vs 149 ± 17 ms; P < .0001). The site of origin of the PVC had an impact on the PVC-QRS width, with epicardial PVCs having the broadest QRS complexes. Patients with PVCs originating from the right ventricular outflow tract or the fascicles had the narrowest QRS complexes. After adjusting for PVC burden, symptom duration, and PVC site of origin, PVC-QRS width and an epicardial PVC origin were independently associated with rPVC-CMP. Based on receiver operator characteristics analysis, a QRS duration of >150 ms best differentiated patients with and without rPVC-CMP (area under the curve 0.66; sensitivity 80%; specificity 52%). The PVC burden for developing rPVC-CMP is significantly lower in patients with a PVC-QRS width of ≥150 ms than in patients with a narrower PVC-QRS complex (22% ± 13% vs 28% ± 12%; P < .0001)., Conclusion: Broader PVCs and an epicardial PVC origin are associated with the development of rPVC-CMP independent of the PVC burden., (Copyright © 2012 Heart Rhythm Society. All rights reserved.)