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Atrial fibrillation (AF), the most common sustained arrhythmia observed in clinical practice, is a chronic and progressive disorder characterized by exacerbations and remissions. Guidelines recommend antiarrhythmic drugs as the initial therapy for the maintenance of sinus rhythm; however, antiarrhythmic drugs have modest efficacy to maintain sinus rhythm and can be associated with significant adverse effects. An initial treatment strategy of cryoballoon catheter ablation in patients with treatment-naive AF has been shown to significantly improve arrhythmia outcomes (freedom from any, or symptomatic atrial tachyarrhythmia), produce clinically meaningful improvements in patient-reported outcomes (symptoms and quality of life), and significantly reduce subsequent health care resource use (hospitalization), and it does not increase the risk of serious or any adverse events compared with initial antiarrhythmic drug therapy. These findings are relevant to inform patients, providers, and health care systems regarding the initial choice of rhythm-control therapy in patients with treatment-naive AF.

Evidence has accumulated over the last century of the importance of a critical electrical mass in sustaining atrial fibrillation (AF). AF ablation certainly reduces electrically contiguous atrial mass, but this is not widely accepted to be an important part of its mechanism of action. In this article, we review data showing that atrial size is correlated in many settings with AF propensity. Larger mammals are more likely to exhibit AF. This is seen both in the natural world and in animal models, where it is much easier to create a goat model than a mouse model of AF, for example. This also extends to humans—athletes, taller people, and obese individuals all have large atria and are more likely to exhibit AF. Within an individual, risk factors such as hypertension, valvular disease and ischaemia can enlarge the atrium and increase the risk of AF. With respect to AF ablation, we explore how variations in ablation strategy and the relative effectiveness of these strategies may suggest that a reduction in electrical atrial mass is an important mechanism of action. We counter this with examples in which there is no doubt that mass reduction is less important than competing theories such as ganglionated plexus ablation. We conclude that, when considering future strategies for the ablative therapy of AF, it is important not to discount the possibility that contiguous electrical mass reduction is the most important mechanism despite the disappointing consequence being that enhancing success rates in AF ablation may involve greater tissue destruction.

Background Guidelines recommend a trial of one or more antiarrhythmic drugs before catheter ablation is considered in patients with atrial fibrillation. However, first-line ablation may be...

Use of intraprocedural observation and pharmacologic challenges have been proposed as means to differentiate permanent pulmonary vein (PV)-left atrial conduction block from inadequate ablation lesions.The purpose of this study was to determine the prevalence and clinical impact of spontaneous and adenosine-provoked reconnection using contemporary atrial fibrillation (AF) ablation technologies.The CIRCA-DOSE (Cryoballoon vs. Irrigated Radiofrequency Catheter Ablation: Double Short vs. Standard Exposure Duration) study enrolled 346 patients with paroxysmal AF and randomized them to contact force-guided radiofrequency ablation (CF-RF) or cryoballoon ablation. Patients underwent provocative testing with adenosine after a 20-minute observation period. All patients received an implantable cardiac monitor for arrhythmia monitoring.Spontaneous reconnection was observed in 5.4% of PVs (71/1318) during the 20-minute postprocedure observation period, and dormant conduction was elicited in 5.7% of PVs (75/1318). Both spontaneous reconnection and dormant conduction were more common after CF-RF compared to cryoballoon ablation (P = .03 and P.0001, respectively). Acute PV reconnection (spontaneous or adenosine-provoked) was associated with a significantly higher incidence of recurrent atrial tachyarrhythmia in the cryoballoon group (hazard ratio [HR] 2.39; 95% confidence interval [CI] 1.44-3.96; P = .0007) but not in the CF-RF group (HR 1.47; 95% CI 0.84-2.58; P = .16). In the absence of acute reconnection, the freedom from recurrent arrhythmia did not differ between groups (HR 0.95; 95% CI 0.6057-1.495; P = .83).Patients without spontaneous or adenosine-provoked reconnection had better outcomes compared to those with acute PV reconnection, suggesting that efforts should be directed toward ensuring an ideal ablation lesion at the first attempt in order to achieve durable PV isolation.

Contemporary guidelines recommend that atrial fibrillation (AF) be classified into paroxysmal and persistent AF based on clinical assessment, with these categorizations forming the basis of therapeutic recommendations. While pragmatic, clinical assessment may introduce misclassification errors, which may impact treatment decisions. We sought to determine the relationship between AF classification, baseline AF burden, and post-ablation arrhythmia outcomes.The current study is a sub-analysis of a prospective, parallel-group, multicenter, single-blinded randomized clinical trial. All 346 patients enrolled in CIRCA-DOSE received an implantable cardiac monitor a median of 72 days prior to ablation. AF was classified as low burden paroxysmal, high burden paroxysmal, or persistent based on clinical assessment prior to device implantation. Prior to ablation patients were re-classified using the same definitions based on device monitoring data. Correlation between classifications, AF burden, and post-ablation arrhythmia outcomes were assessed.There was poor agreement between clinical and device-based AF classification (Cohen's kappa: 0.192). AF classification derived from pre-ablation continuous monitoring reflected baseline and post-ablation AF burden with greater accuracy and with less overlap between the AF classes (P 0.01 for all categorical comparisons). Patients objectively classified as "Low Burden" paroxysmal by continuous monitoring data had significantly greater freedom from recurrent AF/AT/AFL compared to those classified as "High Burden" paroxysmal (hazard ratio [HR] 0.57 for AF/AT/AFL recurrence) or persistent AF (HR 0.19 for AF/AT/AFL recurrence).Classification of AF pattern based on pre-ablation continuous cardiac rhythm monitoring better predicted AF burden and freedom from recurrent AF post ablation. Despite the use of standardized definitions, classification of AF based on clinical assessment did not predict baseline AF burden, post ablation AF burden, or freedom from recurrent AF post ablation.ClinicalTrials.govNCT01913522.

This study sought to determine, in patients with new-onset persistent left bundle branch block (NOP-LBBB) after transcatheter aortic valve implantation (TAVI), the incidence and factors associated with (i) LBBB recovery and (ii) permanent pacemaker implantation (PPI) at 1-year follow-up. This was a multicenter study including 153 patients (mean age: 81 ± 5 years, 56% of women) with NOP-LBBB post-TAVI (balloon-expandable valve in 112 patients). Delta PR (ΔPR) and delta QRS (ΔQRS) were defined as the difference in PR and QRS length between baseline and hospital discharge ECG, and the relative ΔPR and ΔQRS as absolute ΔPR and ΔQRS divided by baseline PR and QRS length, respectively. The patients had a clinical visit and 12-lead ECG at 1-year follow-up. LBBB recovery was observed in 50 patients (33%), and 14 patients (9%) had advanced conduction disturbances requiring PPI during the follow-up period. No clinical or ECG variables were associated with LBBB recovery, including prosthesis type (self- or balloon-expandable valve, p = 0.563), QRS width at baseline/discharge or absolute/relative ΔQRS (p >0.10 for all). The presence of atrial fibrillation at baseline (0.026), a longer PR interval at discharge (0.009), and a longer absolute and relative ΔPR (p = 0.002 and p = 0.004, respectively) were associated with an increased risk of PPI at 1-year follow-up. In conclusion, NOP-LBBB post-TAVI resolved in one-third of patients at 1-year follow-up, but no clinical or ECG variables were associated with LBBB recovery. Conversely, a nonsinus rhythm at baseline and a longer ΔPR were associated with an increased risk of PPI within the year after TAVI.

Key Points Question What proportion of patients with left ventricular dysfunction identified during hospitalization for acute myocardial infarction have follow-up assessment of left ventricular ejection fraction (LVEF)? Findings In this cohort study of 501 patients, 303 patients had undergone LVEF reassessment by 6 months, with significant variability according to patient-level and site-level characteristics. Meaning These findings suggest that programs to improve the quality of post–myocardial infarction care should include measures to ensure that indicated repeat cardiac imaging is performed., This cohort study assesses adherence with guideline-recommended left ventricular ejection fraction (LVEF) reassessment after myocardial infarction and studies the evolution of LVEF over 6 months of follow-up in the Acute Myocardial Infarction Quality Assurance (AMIQA) Canada study., Importance Persistently depressed left ventricular ejection fraction (LVEF) after myocardial infarction (MI) is associated with adverse prognosis and directs the use of evidence-based treatments to prevent sudden cardiac death and/or progressive heart failure. Objective To assess adherence with guideline-recommended LVEF reassessment and to study the evolution of LVEF over 6 months of follow-up. Design, Setting, and Participants This was a multicenter cohort study at Canadian academic and community hospitals with on-site cardiac catheterization services. Patients with type 1 acute MI and LVEF less than or equal to 45% during the index hospitalization were enrolled between January 2018 and August 2019 and were followed-up for 6 months. Data analysis was performed from May 2020 to September 2021. Exposures Baseline clinical factors, in-hospital care and LVEF, and site-specific features. Main Outcomes and Measures The main outcomes were receipt of repeat LVEF assessment by 6 months and the presence of a persistent LVEF reduction at 2 thresholds: LVEF less than or equal to 40%, prompting consideration of additional medical therapy for heart failure, or LVEF less than or equal to 35%, prompting referral for implanted cardioverter defibrillator in addition to medical therapy. Results This study included 501 patients (mean [SD] age, 63.3 [13.0] years; 113 women [22.6%]). Overall, 370 patients (73.4%) presented with STEMI, and 454 (90.6%) had in-hospital revascularization. The median (IQR) baseline LVEF was 40% (34%-43%). Of 458 patients (91.4%) who completed the 6-month follow-up, 303 (66.2%; 95% CI, 61.7%-70.5%) had LVEF reassessment, with a range of 46.7% to 90.0% across sites (χ213 = 19.6; P = .11). Participants from community hospitals were more likely than those from academic hospitals to undergo LVEF reassessment (73.6% vs 63.2%; χ21 = 4.50; P = .03), as were those with worse LVEF at baseline. Follow-up LVEF improved by an absolute median (IQR) of 8% (3%-15%). However, 103 patients (34.1%) met the definitions of clinically relevant LVEF reduction, including 52 patients (17.2%) with LVEF less than or equal to 35% and 51 patients (16.9%) with LVEF of 35.1% to 40.0%. Conclusions and Relevance In this cohort study, approximately 1 in 3 patients with at least mild LVEF reduction after acute MI did not undergo indicated LVEF reassessment within 6 months, suggesting that programs to improve the quality of post-MI care should include measures to ensure that indicated repeat cardiac imaging is performed. In those with follow-up imaging, clinically relevant persistent LVEF reduction was identified in more than one-third of patients.

Background: Various noninvasive intermittent rhythm monitoring strategies have been used to assess arrhythmia recurrences in trials evaluating pharmacological and invasive therapeutic interventions for atrial fibrillation (AF). We determined whether a frequency and duration of noninvasive rhythm monitoring could be identified that accurately detects arrhythmia recurrences and approximates the AF burden derived from continuous monitoring using an implantable cardiac monitor (ICM). Methods: The rhythm history of 346 patients enrolled in the CIRCA-DOSE trial (Cryoballoon Versus Contact-Force Irrigated Radiofrequency Catheter Ablation) was reconstructed. Using computer simulations, we evaluated event-free survival, sensitivity, negative predictive value, and AF burden of a range of noninvasive monitoring strategies, including those used in contemporary AF ablation trials. Results: A total of 126 290 monitoring days were included in the analysis. At 12 months, 164 patients experienced atrial arrhythmia recurrence as documented by the ICM (1-year event-free survival, 52.6%). Most noninvasive monitoring strategies used in AF ablation trials had poor sensitivity for detecting arrhythmia recurrence. Sensitivity increased with the intensity of monitoring, with serial (3) short-duration monitors (24-/48-hour ECG monitors) missing a substantial proportion of recurrences (sensitivity, 15.8% [95% CI, 8.9%–20.7%] and 24.5% [95% CI, 16.2%–30.6%], respectively). Serial (3) longer-term monitors (14-day ECG monitors) more closely approximated the gold standard ICM (sensitivity, 64.6% [95% CI, 53.6%–74.3%]). AF burden derived from short-duration monitors significantly overestimated the true AF burden in patients with recurrences. Increasing monitoring duration resulted in improved correlation and concordance between noninvasive estimates of the invasive AF burden ( R 2 = 0.85 and interclass correlation coefficient = 0.91 for serial [3] 14-day ECG monitors versus ICM). Conclusions: The observed rate of postablation atrial tachyarrhythmia recurrence is highly dependent on the arrhythmia monitoring strategy employed. Between-trial discrepancies in outcomes may reflect different monitoring protocols. On the basis of measures of agreement, serial long-term (7–14 day) intermittent monitors accumulating at least 28 days of annual monitoring provide estimates of AF burden comparable with ICM. However, ICMs outperform intermittent monitoring for arrhythmia detection, and should be considered the gold standard for clinical trials. Registration: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT01913522.

Background The role of cardiac magnetic resonance (CMR) imaging in the diagnostic evaluation of patients with frequent premature ventricular complexes (PVCs) and normal left ventricular ejection fraction (LVEF) remains unclear. Existing data has been predominantly derived from highly selected populations, that may overestimate the true prevalence of abnormal findings on CMR in this patient population. Purpose The aim of this study was 2-fold: 1) to establish the prevalence of CMR imaging abnormalities in a cohort with normal LVEF and high PVC burden; 2) to identify predictors of CMR imaging abnormalities in patients with frequent PVCs and normal LVEF. Methods In this cohort study, 211 patients (age 53.2±19 years; 41% male) with frequent PVCs (≥5%/24 h), of normal LVEF (≥50% by echocardiography) and no known underlying structural heart disease were prospectively enrolled from 2016–2020. Of these, 166 (79%) patients were symptomatic from their PVCs in the form of palpitations, fatigue, chest pain, dizziness, and/or dyspnea. Patients underwent CMR imaging (1.5 Tesla) with a late gadolinium enhancement (LGE) protocol at the time of enrollment for the detection of scarring and/or fibrosis. Results Patients had a median baseline echocardiographic LVEF of 60% (± 5%) with 195 (92%) of patients having a normal native QRS morphology. Median PVC burden of the study cohort was 16% (± 14%). CMR LGE abnormalities were found in 19 (9%) patients including 17 scans with non-ischemic LGE and 2 with ischemic LGE. Age >60 (odds ratio [OR]: 3.20, 95% confidence interval [CI]: 1.20–8.51, p=0.020), male sex (OR: 4.67, 95% CI: 1.61–13.50, p=0.004), history of hypertension (OR: 3.43, 95% CI: 1.31–8.97, p=0.012), native QRS duration (OR: 1.03, 95% CI: 1.00–1.05, p=0.031), and history of non-sustained ventricular tachycardia (OR: 2.81, 95% CI: 1.03–7.68, p=0.044) were significantly associated with the presence of imaging abnormalities on CMR. Dominant PVC origin from the left ventricle had a positive trend (OR: 2.60, 95% CI: 0.99–7.66, p=0.083) to association with CMR imaging abnormalities. On multivariate analysis, male sex (OR: 4.10, 95% CI: 1.40–12.04, p=0.010) and history of hypertension (OR: 2.89, 95% CI: 1.08–7.75, p=0.035) remained significantly associated with the presence of CMR abnormalities. There was no association between CMR imaging abnormalities and the burden of PVCs or the number of PVC morphologies. Conclusion In this cohort, only 9% of patients with apparently idiopathic frequent PVCs and normal LVEF had concealed myocardial abnormalities on CMR imaging. Male sex and history of hypertension were associated with a higher rate of CMR abnormalities. Funding Acknowledgement Type of funding sources: None.

Sudden cardiac death (SCD) risk stratification in hypertrophic cardiomyopathy (HCM) currently relies on arrhythmic burden quantification by 24 or 48-hour Holter monitoring. Whether this approach adequately captures arrhythmic burden, compared with longer-term continuous monitoring, is unclear. We sought to assess the long-term incidence of nonsustained ventricular tachycardia (NSVT) in HCM patients at low or moderate SCD risk, using implantable cardiac monitors (ICMs) paired with a novel Bluetooth-enabled 2-way communication platform.This prospective, single-arm, observational study enrolled 33 HCM patients. Patients were implanted with an Abbott (Chicago, IL) Confirm Rx ICM and monitored using a protocolized care pathway.A total of 20 patients (60.6%) had ≥ 1 episode of NSVT recorded on the ICM, the majority of whom had previous Holter monitors that did not identify NSVT (60%, n = 12). A total of 71 episodes of NSVT were detected. Median time to first NSVT detection was 76.5 days (range: 0-553 days). A total of 19 patients underwent primary prevention implantable cardioverter defibrillator implantation during an average follow-up of 544 days (range: 42-925 days). A total of 172,112 automatic transmissions were received, and 65 (0.04%) required clinical follow-up. A total of 325 manual transmissions were received and managed. A total of 14 manual transmissions (4.3%) required follow-up, whereas 311 (95.7%) were managed solely with a text message.Surveillance and reporting systems utilizing 2-way communication enabled by novel ICMs are feasible and allow remote management of patients with HCM. Prolonged monitoring with ICMs identified more patients with nonsustained arrythmias than did standard Holter monitoring. In many cases, this information impacted both SCD risk stratification and patient management.La stratification du risque de mort cardiaque subite (MCS) dans la cardiomyopathie hypertrophique (CMH) dépend actuellement de la quantification de la charge arythmique par une surveillance Holter de 24 ou 48 heures. Il n’est pas clair si cette approche permet d’évaluer adéquatement la charge arythmique, comparativement à une surveillance continue à plus long terme. Nous avons cherché à évaluer la fréquence à long terme de la tachycardie ventriculaire non soutenue (TVNS) chez des patients atteints de CMH à risque faible ou modéré de MCS, au moyen de moniteurs cardiaques implantables (MCI) couplés à une nouvelle plate-forme de communication bidirectionnelle utilisable avec Bluetooth.Cette étude par observation prospective comportant un seul groupe a été menée auprès de 33 patients atteints de CMH. Les patients ont reçu un MCI Confirm Rx d’Abbott (Chicago, États-Unis) et ont été surveillés dans le cadre d’un parcours de soins reposant sur un protocole.Au total, 20 patients (60,6 %) ont eu au moins un épisode de TVNS enregistré par le MCI. La majorité de ces patients portaient déjà un moniteur Holter qui n’a pas décelé de TVNS (60 %, n = 12). Au total, 71 épisodes de TVNS ont été détectés. Le temps médian écoulé avant la première détection de TVNS était de 76,5 jours (fourchette : 0-553 jours). Au total, 19 patients se sont fait poser un défibrillateur cardioverteur implantable en prévention primaire pendant un suivi moyen de 544 jours (fourchette : 42-925 jours). En tout, 172 112 transmissions automatiques ont été reçues, et 65 (0,04 %) ont nécessité un suivi clinique. Par ailleurs, 325 transmissions manuelles ont été reçues et traitées. De ce nombre, 14 transmissions (4,3 %) ont nécessité un suivi, tandis que 311 (95,7 %) ont été traitées uniquement au moyen d’un message texte.Les systèmes de surveillance et de signalement utilisant une communication bidirectionnelle rendue possible grâce aux nouveaux MCI sont réalisables et permettent une prise en charge à distance des patients atteints d’un CMH. La surveillance prolongée par un MCI a permis de déceler plus d’arythmies non soutenues que la surveillance Holter type. Dans de nombreux cas, ces renseignements ont eu un effet positif tant sur la stratification du risque de MCS que sur la prise en charge des patients.

IMPORTANCE: Patients with atrial fibrillation (AF) have impaired health-related quality of life primarily owing to symptoms related to AF episodes; however, quality of life can be influenced by AF therapies, AF complications, the frequency of follow-up visits and hospitalizations, illness perceptions, and patient factors, such as anxiety or depression. OBJECTIVE: To determine the association between change in AF burden and quality of life in the year following ablation. DESIGN, SETTING, AND PARTICIPANTS: The current study is a secondary analysis of a prospective, parallel-group, multicenter, single-masked randomized clinical trial (Cryoballoon vs Irrigated Radiofrequency Catheter Ablation: Double Short vs Standard Exposure Duration [CIRCA-DOSE] study), which took place at 8 Canadian centers. Between September 2014 and July 2017, 346 patients older than 18 years with symptomatic, primarily low-burden AF refractory to antiarrhythmic therapy referred for first catheter ablation were enrolled. All patients received an implantable cardiac monitor at least 30 days before ablation and were followed up with up to December 2018. Data were analyzed from April 2020 to June 2021. INTERVENTIONS: Patients were randomized 1:1:1 to contact force–guided radiofrequency ablation, 4-minute cryoballoon ablation, or 2-minute cryoballoon ablation. The exposure in the present analysis is the absolute difference in AF burden prior to ablation and 12 months following ablation, as evaluated by the Atrial Fibrillation Effect on Quality of Life (AFEQT) Score. MAIN OUTCOMES AND MEASURES: Absolute difference in quality of life from baseline to 12 months postablation. RESULTS: Of 346 included patients, 231 (66.7%) were male, and the median (interquartile range) age was 60 (52-66) years. A total of 328 patients (94.8%) had paroxysmal AF. The median (interquartile range) preablation AF burden was 2.0% (0.1-11.9), and the AF burden decreased to 0% at 12 months postablation. At 12 months, a 1-point improvement in AFEQT score was observed for every absolute reduction in daily AF burden of 15.8 minutes (95% CI, 7.2-24.4; P

Background: Rate control medications are foundational in the management of persistent atrial fibrillation (AF). There are no guidelines for adjusting these medications prior to elective direct-current cardioversion (DCCV). Objective: To derive and validate a preprocedural medication adjustment protocol that maintains peri-DCCV rate control and minimizes risk of postconversion bradycardia, pauses, need for pacing, and cardiopulmonary resuscitation (CPR). Methods: Consecutive patients with persistent AF awaiting elective DCCV across 2 hospitals were screened for inclusion into derivation, validation, and control cohorts. In the derivation cohort, each patient taking an atrioventricular (AV) nodal blocker had medications adjusted based on heart rate (HR) 2 days before DCCV, and the magnitude of dose adjustment was compared with peri-DCCV HR. The adjustment protocol that achieved the highest percentage of optimal peri-DCCV rate control was tested prospectively in the validation cohort and compared to a standard-of-care control group. Results: The optimal protocol from the derivation cohort (n = 71), based on the 2-day pre-DCCV HR, was to (1) CONTINUE AV nodal blocker for HR ≥ 100 beats per minute (bpm), (2) reduce dose by ONE increment when 80–99 bpm, (3) reduce dose by TWO increments when 60–79 bpm, and (4) HOLD when

After the most common causes of sudden cardiac death including ischemic and structural heart disease have been ruled out, clinicians on the front lines of emergent medical care can be faced with unexplained and recurrent life-threatening arrhythmia episodes in children and adults. In these cases, an inherited arrhythmia syndrome should be suspected, and a departure from conventional advanced cardiac life support algorithms may be required. This review focuses on the electrocardiographic clues of an inherited arrhythmia syndrome that can be uncovered through a careful analysis of the baseline electrocardiogram (ECG) and classification of the presenting ventricular arrhythmia and its mode of onset. After presenting an informed working diagnosis and an explanation of the implied electrophysiologic mechanisms, discussion provides a protocol approach to acute and subacute management decisions. Careful attention to a patient's response to treatment and its ECG surrogates have the potential to facilitate tailored therapy based on the underlying arrhythmogenic substrate and pathophysiology.

OBJECTIVE: A higher premature ventricular complex (PVC) frequency is associated with incident congestive heart failure (CHF) and death. While certain PVC characteristics may contribute to that risk, the current literature stems from patients in medical settings and is therefore prone to referral bias. This study aims to identify PVC characteristics associated with incident CHF in a community-based setting. METHODS: The Cardiovascular Health Study (CHS) is a cohort of community-dwelling individuals that underwent prospective evaluation and follow-up. We analyzed 24-hour Holter data to assess PVC characteristics and used multivariable logistic and Cox proportional hazards models to identify predictors of a left ventricular ejection fraction (LVEF) decline and incident CHF, respectively. RESULTS: Of 871 analyzed participants, 316 participants exhibited at least 10 PVCs during the 24-hour recording. For participants with PVCs, the average age was 72 ± 5 years, 41% were women, and 93% were white. Over a median follow up of 11 years, 34% developed CHF. After adjusting for demographics, cardiovascular comorbidities, antiarrhythmic drug use, and PVC frequency, a greater heterogeneity of the PVC coupling interval was associated with an increased risk of LVEF decline and incident CHF. Of note, neither PVC duration nor coupling interval duration exhibited a statistically significant relationship with either outcome. CONCLUSIONS: In this first community-based study to identify Holter-based features of PVCs that are associated with LVEF reduction and incident CHF, the fact that coupling interval heterogeneity was an independent risk factor suggests that the mechanism of PVC generation may influence the risk of heart failure.

BACKGROUND The value of cardiac magnetic resonance (CMR) imaging in evaluating patients with frequent premature ventricular complexes (PVCs) is uncertain. Prior studies in highly selected populations may overestimate the prevalence of abnormal findings on CMR. This study aimed to: 1) define the prevalence of CMR imaging abnormalities in a cohort with high PVC burden; 2) identify predictors of CMR imaging abnormalities in patients with frequent PVCs. METHODS AND RESULTS 264 patients (age 55.0 ± 16 years; 48% male) with frequent PVCs (≥ 5%/24 h) and no known structural heart disease were prospectively enrolled from 2016-2020. Those with unexplained reduced, global left ventricular function were included, if no other evidence of structural disease was evident on initial work-up. Of these, 202 (77%) patients were symptomatic with palpitations, fatigue, chest pain, dizziness, and/or dyspnea. Patients underwent CMR imaging (1.5 Tesla) with late gadolinium enhancement (LGE) protocol at baseline for the detection of scar/fibrosis. The median baseline echocardiographic left ventricular ejection fraction (LVEF) was 57% (Interquartile Range [IQR] 51-60%) and 240 (91%) had a normal native QRS morphology. Median PVC burden was 17% (IQR 11-25%). CMRs with suboptimal imaging quality were independently adjudicated. CMR LGE was found in 34 (13%), including 27 (10%) with LGE in a non-ischemic distribution and 7 (3%) in an ischemic distribution (occult myocardial infarction). Several predictors were significant univariate but not multivariate predictors of LGE presence, including male sex, history of hypertension, and non-sustained ventricular tachycardia (see Table 1). Significant multivariate predictors were: age ≥ 60 (OR: 5.48 [2.29-13.11]), LVEF CONCLUSION Among patients with apparently idiopathic PVCs on initial workup, 13% demonstrated myocardial abnormalities on CMR imaging. Age ≥ 60 years, LVEF

Early recurrence of atrial tachyarrhythmia (ERAT) is common after pulmonary vein isolation (PVI) and has been associated with an increased risk of late atrial fibrillation (AF) recurrence.The purpose of this study was to determine the incidence and outcomes of patients experiencing ERAT after PVI using advanced-generation ablation technologies.This is a prespecified substudy of the CIRCA-DOSE (Cryoballoon vs Irrigated Radiofrequency Catheter Ablation: Double-Short vs Standard Exposure Duration) trial, a prospective, randomized, multicenter study comparing PVI with contact force-guided radiofrequency ablation to secondary-generation cryoballoon ablation for paroxysmal AF. All study patients received an implantable cardiac monitor to allow continuous rhythm monitoring. ERAT was defined as any recurrent atrial tachyarrhythmia within the first 90 days after AF ablation.ERAT occurred in 61% of the 346 patients at a median of 12 days (range 1-90 days) after ablation. ERAF was a significant predictor of late recurrence (60.1% with ER vs 25.9% without ER; P.001) and symptomatic atrial tachyarrhythmia (31.6% with ERAF vs 6.7% without ERAF; P.001). Receiver operating curve analyses revealed a strong correlation between ERAT timing and burden and late recurrence. Multivariate analysis identified ER timing (hazard ratio [HR] 2.90; 95% confidence interval [CI] 1.41-5.95; P = .004) and burden (HR 1.05 per 1% ER burden; 95% CI 1.04-1.07; P.001) as strong independent predictors of late recurrence. Incidence rate, timing, burden, and prognostic significance of ER did not differ between the study groups.ERAT remains common after PVI despite use of advanced-generation ablation technologies. Early AF recurrence beyond 3 weeks after ablation is associated with increased risk of late recurrence.

Background The natural history of autonomic alterations following catheter ablation of drug‐refractory paroxysmal atrial fibrillation is poorly defined, largely because of the historical reliance on non‐invasive intermittent rhythm monitoring for outcome ascertainment. Methods and Results The study included 346 patients with drug‐refractory paroxysmal atrial fibrillation undergoing pulmonary vein isolation using contemporary advanced‐generation ablation technologies. All patients underwent insertion of a Reveal LINQ (Medtronic) implantable cardiac monitor before ablation. The implantable cardiac monitor continuously recorded physical activity, heart rate variability (measured as the SD of the average normal‐to‐normal), daytime heart rate, and nighttime heart rate. Longitudinal autonomic data in the 2‐month period leading up to the date of ablation were compared with the period from 91 to 365 days following ablation. Following ablation there was a significant decrease in SD of the average normal‐to‐normal (mean difference versus baseline of 19.3 ms; range, 12.9–25.7; P P P P =0.001) and nighttime heart rates (8±9 versus 6±8 bpm, P =0.049), but no difference in SD of the average normal‐to‐normal ( P =0.09) compared with those with atrial fibrillation recurrence. Ablation technology and cryoablation duration did not influence these autonomic nervous system effects. Conclusions Pulmonary vein isolation results in significant sustained changes in the heart rate parameters related to autonomic function. These changes are correlated with procedural outcome and are independent of the ablation technology used. Registration URL: https://www.clinicaltrials.gov ; Unique identifier: NCT01913522.

Aims We determined the incidence and type of arrhythmias at 2-year follow-up in patients with new-onset persistent left bundle branch block (LBBB) following transcatheter aortic valve replacement (TAVR). Methods and results Multicentre prospective study including 103 consecutive patients with new-onset persistent LBBB post-TAVR (SAPIEN XT/3: 53; CoreValve/Evolut R: 50). An implantable cardiac monitor (Reveal XT, Reveal Linq) was implanted before hospital discharge and patients had continuous monitoring for up to 2 years. Arrhythmic events were adjudicated in a central core lab. 1836 new arrhythmic events (tachyarrhythmias: 1655 and bradyarrhythmias: 181) occurred at 2 years. Of these, 283 (15%) occurred beyond 1 year (tachyarrhythmias 212, bradyarrhythmias 71) in 33 (36%) patients, without differences between valve type. Most late (>1 year) arrhythmic events were asymptomatic (94%) and led to a treatment change in 17 (19%) patients. A total of 71 late bradyarrhythmias [high-degree atrioventricular block (HAVB): 3, severe bradycardia: 68] were detected in 17 (21%) patients. At 2 years, 18 (17%) patients had received a permanent pacemaker (PPM) or implantable cardiac-defibrillator. PPM implantation due to HAVB predominated in the early phase post-TAVR, with only 1 HAVB event requiring PPM implantation after 1 year. Conclusion Patients with new-onset LBBB post-TAVR exhibited a very high burden of arrhythmic events within the 2 years post-procedure. While new tachyarrhythmic events were homogeneously distributed over time, the vast majority of new HAVB episodes leading to PPM implantation occurred early after the procedure. These results should help to guide the management of this challenging group of patients. (clinicaltrials.gov: NCT02153307)

Background Concerns remain regarding the effectiveness of PVI using the fixed diameter non-compliant cryoballoon in the presence of a left common pulmonary vein (LCPV). We sought to evaluate the effectiveness of PVI performed by contact-force guided radiofrequency (CF-RF) versus second-generation cryoballoon-based ablation in patients with LCPV. Methods and results We enrolled 346 patients with paroxysmal AF and randomized them to CF-RF or cryoballoon ablation. PV anatomy was not assessed prior to enrolment, and there were no exclusions based on PV anatomy. All patients received an implantable cardiac monitor. LCPV was observed in 13.6% of patients (47/346). Left atrial time and fluoroscopy time did not differ between those with and without LCPV (P=0.58 and P=0.06, respectively). Freedom from any atrial tachyarrhythmia at one year was observed in 46.8% with LCPV and 54.5% without LCPV (P=0.06). In those with LCPV the freedom from any atrial tachyarrhythmia did not differ between those randomized to CF-RF or cryoballoon ablation (HR for recurrence 1.19, 95% CI 0.53-2.65, P=0.69). In those with LCPV the AF burden was reduced to a similar extent with CF-RF and cryoballoon ablation (99.7% vs. 99.5%, respectively; P=0.97). Conclusions In this randomized clinical trial, the presence of a LCPV was associated with a trend towards higher rates of arrhythmia recurrence following PVI. No significant difference in arrhythmia recurrence was observed between patients with LCPV randomized to cryoballoon ablation or contact-force guided RF ablation, suggesting that either ablation modality is suitable in this population. (Cryoballoon vs. Irrigated Radiofrequency Catheter Ablation [CIRCA-DOSE], NCT01913522) This article is protected by copyright. All rights reserved.

Objectives The authors sought to determine: 1) the global arrhythmic burden; 2) the rate of arrhythmias leading to a treatment change; and 3) the incidence of high-degree atrioventricular block (HAVB) at 12-month follow-up in patients with new-onset persistent left bundle branch block (LBBB) following transcatheter aortic valve replacement (TAVR). Background Controversial data exist on the occurrence of significant arrhythmias in patients with LBBB post-TAVR. Methods This was a multicenter prospective study including 103 consecutive patients with new-onset persistent LBBB post-TAVR with the balloon-expandable SAPIEN XT/3 valve (n = 53), or the self-expanding CoreValve/Evolut R system (n = 50). An implantable cardiac monitor (Reveal XT, Reveal Linq) was implanted at 4 (3 to 6) days post-TAVR, and patients had continuous electrocardiogram monitoring for 12 months. All arrhythmic events were adjudicated in a central electrocardiography core lab. Primary endpoints were the incidence of arrhythmias leading to a treatment change, and the incidence of HAVB at 12-month follow-up. Results A total of 1,553 new arrhythmic events were detected in 44 patients (1,443 episodes of tachyarrhythmia in 26 patients [atrial fibrillation/flutter/atrial tachycardia: 1,427, ventricular tachycardia 16]; 110 episodes of bradyarrhythmia in 21 patients [HAVB 54, severe bradycardia 56]). All arrhythmic events were silent in 34 patients (77%), the arrhythmic event led to a treatment change in 19 patients (18%), and 11 patients (11%) required pacemaker or implantable cardioverter-defibrillator implantation (due to HAVB, severe bradycardia, or ventricular tachycardia episodes in 9, 1, and 1 patient, respectively). A total of 12 patients died at 1-year follow-up, 1 from sudden death. Conclusions A high incidence of arrhythmic events was observed at 1-year follow-up in close to one-half of the patients with LBBB post-TAVR. Significant bradyarrhythmias occurred in one-fifth of the patients, and PPM was required in nearly one-half of them. These data support the use of a cardiac monitoring device for close follow-up and expediting the initiation of treatment in this challenging group of patients. (Ambulatory Electrocardiographic Monitoring for the Detection of High-Degree Atrio-Ventricular Block in Patients With New-onset PeRsistent LEft Bundle Branch Block After Transcatheter Aortic Valve Implantation [MARE study]: NCT02153307)

Objectives This study sought to evaluate the predictive value of noninducibility on long-term outcomes. Background The traditional endpoint for catheter ablation of ventricular tachycardia (VT) is noninducibility of VT by programmed stimulation; however, the definition of inducibility remains variable and its prognostic value limited by nonstandardized periprocedural antiarrhythmic drug therapy and implantable cardioverter-defibrillator programming in prior observational studies. The VANISH trial randomized patients with prior myocardial infarction and VT to ablation (with an endpoint of noninducibility of VT ≥300 ms after ablation) versus antiarrhythmic drug escalation. Methods Patients enrolled in the VANISH study randomized to catheter ablation were included. The relationship between post-ablation inducibility and the primary composite endpoint (death, VT storm >30 days, or appropriate implantable cardioverter-defibrillator shock >30 days) was assessed using a time-to-event analysis, adjusting for other clinical and procedural characteristics. Results A total of 129 patients from the ablation arm were included in the primary analysis, of which 51 were noninducible post-ablation compared with 78 who had inducible VT or in whom inducibility testing was not performed. There were no significant baseline characteristic or procedural differences except for increased implantable cardioverter-defibrillator shocks before randomization in the noninducible group. In multivariate analysis, inducibility significantly increased the risk of death, appropriate shock, or VT storm after 30 days (HR: 1.87; p = 0.017). Conclusions Inducibility of any VT post-ablation was associated with an increased risk of the composite endpoint in the VANISH trial. A randomized trial is required to confirm whether more aggressive ablation targeting faster induced VTs (

Atrial fibrillation and heart failure are increasing in prevalence, and frequently coexist. Despite the desire to restore sinus rhythm in heart failure patients, large studies comparing rate control to pharmacologic rhythm control have failed to show superiority of either approach. This may in part be due to the inefficacy and higher risk of adverse effects with antiarrhythmic drugs in HF patients. As such, catheter ablation for atrial fibrillation in patients with heart failure with reduced ejection fraction has been increasingly explored as a treatment modality. We review the contemporary evidence regarding patient selection, efficacy, safety, and impact of catheter ablation on outcomes in patients with atrial fibrillation and heart failure with reduced ejection fraction.

OBJECTIVES: The authors studied the response rates and relative sensitivity of the most common agents used in the sodium-channel blocker (SCB) challenge. BACKGROUND: A type 1 Brugada electrocardiographic pattern precipitated by an SCB challenge confers a diagnosis of Brugada syndrome. METHODS: Patients undergoing an SCB challenge were prospectively enrolled across Canada and the United Kingdom. Patients with no prior cardiac arrest and family histories of sudden cardiac death or Brugada syndrome were included. RESULTS: Four hundred twenty-five subjects underwent SCB challenge (ajmaline, n = 331 [78%]; procainamide, n = 94 [22%]), with a mean age of 39 ± 15 years (54% men). Baseline non-type 1 Brugada ST-segment elevation was present in 10%. A total of 154 patients (36%) underwent signal-averaged electrocardiography, with 41% having late potentials. Positive results were seen more often with ajmaline than procainamide infusion (26% vs. 4%, p < 0.001). On multivariate analysis, baseline non-type 1 Brugada ST-segment elevation (odds ratio [OR]: 6.92; 95% confidence interval [CI]: 3.15 to 15.2; p < 0.001) and ajmaline use (OR: 8.76; 95% CI: 2.62 to 29.2; p < 0.001) were independent predictors of positive results to SCB challenge. In the subgroup undergoing signal-averaged electrocardiography, non-type 1 Brugada ST-segment elevation (OR: 9.28; 95% CI: 2.22 to 38.8; p = 0.002), late potentials on signal-averaged electrocardiography (OR: 4.32; 95% CI: 1.50 to 12.5; p = 0.007), and ajmaline use (OR: 12.0; 95% CI: 2.45 to 59.1; p = 0.002) were strong predictors of SCB outcome. CONCLUSIONS: The outcome of SCB challenge was significantly affected by the drug used, with ajmaline more likely to provoke a type 1 Brugada electrocardiographic pattern compared with procainamide. Patients undergoing SCB challenge may have contrasting results depending on the drug used, with potential clinical, psychosocial, and socioeconomic implications.

ObjectiveThe natural history of frequent premature ventricular complexes (PVCs) in association with preserved left ventricular ejection fraction (LVEF) is uncertain. The optimal management of this population is thus undefined. We studied the outcomes of untreated patients with frequent PVCs and preserved LVEF.MethodsThis cohort study prospectively evaluated consecutive patients from 2012 to 2017, with asymptomatic or minimally symptomatic frequent idiopathic PVCs (≥5% PVCs in 24 hours; normal LVEF; no cause identified on comprehensive evaluation). No suppressive therapy (ablation or antiarrhythmic drugs) were used and patients were followed with serial ambulatory ECG monitoring and echocardiography. The primary arrhythmic outcome was reduction in PVC burden to ResultsOne hundred patients met inclusion criteria (mean age 51.8 years, 57% female) with a median PVC burden of 18.4%. Reduction to ConclusionsA strategy of active surveillance is appropriate for the majority of patients with frequent idiopathic PVCs in association with preserved LVEF, owing to the low risk of developing left ventricular systolic dysfunction and the high rate of spontaneous resolution.

There has been a resurgent interest in frequent premature ventricular contractions (PVCs) led by the novel concept that they may be a potential cause of, or at least contribute to, cardiomyopathy. This review evaluates recent advances in our understanding of PVC-induced cardiomyopathy.Recent studies have focused on identifying the predictors of PVC-induced cardiomyopathy, with the most consistent predictors being PVC burden and PVC QRS duration. Multiple studies have investigated the effect of catheter ablation on PVC burden and resultant left ventricular function, with the efficacy of catheter ablation and the overall PVC response rates varying between 60 and 88%. After successful ablation, the rates of improvement in left ventricular ejection fraction have varied between 47 and 100%. A recent study raises the question that perhaps even a lower PVC burden could result in PVC cardiomyopathy and adverse outcomes.There is an increasing body of literature supporting a causal role of frequent PVCs in the development of left ventricular dysfunction. Effective therapy for PVCs exists; however, the optimal indications for therapy have yet to be determined.

Key Points Question What is the association between preablation atrial fibrillation (AF) episode duration and arrhythmia recurrence outcomes following AF ablation? Findings In this prespecified subanalysis of a randomized clinical trial of 346 patients with symptomatic AF undergoing catheter ablation, patients with AF episodes limited to less than 24 continuous hours had a significantly lower rate of recurrence following an ablation procedure. Arrhythmia recurrence and AF burden after ablation did not differ between patients with persistent AF (episodes lasting >7 days) and those with paroxysmal AF (episodes lasting 24 to 48 hours or 2 to 7 days). Meaning The findings of this study suggest that the contemporary definition of paroxysmal AF does not reflect post-AF ablation arrhythmia outcomes., This secondary analysis of a randomized clinical trial evaluates the association of baseline atrial fibrillation episode duration with post–atrial fibrillation ablation arrhythmia outcomes., Importance Contemporary guidelines recommend that atrial fibrillation (AF) be classified based on episode duration, with these categories forming the basis of therapeutic recommendations. While pragmatic, these classifications are not based on pathophysiologic processes and may not reflect clinical outcomes. Objective To evaluate the association of baseline AF episode duration with post-AF ablation arrhythmia outcomes. Design, Setting, and Participants The current study is a secondary analysis of a prospective, parallel-group, multicenter, single-masked randomized clinical trial (the Cryoballoon vs Irrigated Radiofrequency Catheter Ablation: Double Short vs Standard Exposure Duration [CIRCA-DOSE] study), which took place at 8 Canadian centers. Between September 2014 and July 2017, 346 patients older than 18 years with symptomatic AF referred for first catheter ablation were enrolled. All patients received an implantable cardiac monitor at least 30 days before ablation. Data analysis was performed in September 2019. Exposure Before ablation, patients were classified based on their longest AF episode. Ablation consisted of circumferential pulmonary vein isolation using standard techniques. Main Outcomes and Measures Time to first recurrence of symptomatic or asymptomatic atrial tachyarrhythmia (AF, atrial flutter, or atrial tachycardia) following ablation and AF burden (percentage of time in AF) on preablation and postablation continuous rhythm monitoring. Results The study included 346 patients (mean [SD] age, 59 [10] years; 231 [67.7%] men). Overall, 263 patients (76.0%) had AF episode duration of less than 24 hours; 25 (7.2%), 24 to 48 hours; 40 (11.7%), 2 to 7 days; and 18 (5.2%), more than 7 days. Documented recurrence of any atrial tachyarrhythmia following ablation was significantly lower in patients with baseline AF episode duration of less than 24 continuous hours compared with those with longer AF episodes (24 hours vs 24-48 hours: hazard ratio [HR], 0.41; 95% CI, 0.21-0.80; P = .009; 24 hours vs 2-7 days: HR, 0.25; 95% CI, 0.14-0.45; P 7 days: HR, 0.23; 95% CI, 0.09-0.55; P

Atrial fibrillation (AF) is a progressive chronic disease characterized by exacerbations and periods of remission. It is estimated that up to 20% to 30% of those with AF also have coronary artery disease (CAD), and 5% to 15% will require percutaneous coronary intervention (PCI). In patients with concomitant AF and CAD, management remains challenging and requires a careful and balanced assessment of the risk of bleeding against the anticipated impact on ischemic outcomes (AF-related stroke and systemic embolism, as well as ischemic coronary events). Oral anticoagulation (OAC) is indicated for the prevention of AF-related stroke and systemic embolism, whereas antiplatelet therapy is indicated for the prevention of coronary events. Each offers a relative efficacy benefit (dual antiplatelet therapy [DAPT] is more effective than OAC alone in reducing cardiovascular death, myocardial infarction, stent thrombosis, and ischemic coronary events in a population with acute coronary syndromes [ACS]), but with a relative compromise (DAPT is significantly inferior to OAC for the prevention of stroke/systemic embolism in an AF population at increased risk of stroke). The purpose of this review is to explore the current evidence and rationale for antithrombotic treatment strategies in patients with both AF and CAD. Specifically, there is a focus on how to best tailor the therapeutic choices (OAC and antiplatelet therapy) to individual patients based on their underlying coronary presentation.

Background The ideal management of patients with newly diagnosed symptomatic atrial fibrillation (AF) remains unknown. Current practice guidelines recommend a trial of antiarrhythmic drugs (AAD) prior to considering an invasive ablation procedure. However, earlier ablation offers an opportunity to halt the progressive patho-anatomical changes associated with AF, as well as impart other important clinical benefits. Objective The aim of this study is to determine the optimal initial management strategy for patients with newly diagnosed, symptomatic atrial fibrillation. Methods/Design The EARLY-AF study ( ClinicalTrials.gov NCT02825979 ) is a prospective, open label, multicenter, randomized trial with a blinded assessment of outcomes. A total of 298 patients will be randomized in a 1:1 fashion to first-line AAD therapy, or first-line cryoballoon-based pulmonary vein isolation. Patients with symptomatic treatment naive AF will be included. Arrhythmia outcomes will be assessed by implantable cardiac monitor (ICM). The primary outcome is time to first recurrence of AF, atrial flutter, or atrial tachycardia (AF/AFL/AT) between days 91 and 365 following AAD initiation or AF ablation. Secondary outcomes include arrhythmia burden, quality of life, and healthcare utilization. Discussion The EARLY-AF study is a randomized trial designed to evaluate the optimal first management approach for patients with AF. We hypothesize that catheter ablation will be superior to drug therapy in prevention of AF recurrence.

LIA and LinoxIntroduction Medtronic's Lead Integrity Alert (LIA) software algorithm is useful for detecting abnormal parameters across various ICD-lead families. However, its utility in the assessment of the Biotronik Linox™ family of high-voltage (HV) leads is unknown. Methods We conducted a retrospective cohort study to assess the performance of the LIA algorithm to detect abnormalities and lead failure in Linox ICD-leads. All LIA-enabled Medtronic devices connected to an active Linox lead were included. The alerts were adjudicated by 2 blinded electrophysiologists and correlated with clinical data. Results Between 2008 and 2012, data from 208 patients with 564 patient-years of follow-up were available for analysis. The median follow-up duration was 32 (IQR 21–41 months). Twenty-one LIA triggers were noted in 20 different patients. The median delay until a positive LIA was 32 months (IQR 21–41 months) postimplant with a 5-year lead survival free from LIA of 76%. Ninety-five percent (19/20) LIA alerts were true lead failures. The most common LIA triggers were short V–V intervals (85%) and nonsustained ventricular tachycardia (85%). Abrupt changes of the ICD-lead impedance occurred in 5/20 triggers. Inappropriate ICD-shocks were strongly associated with a positive LIA (30% vs. 7.4%; P = 0.006). Of the explanted Linox leads 53% had visible abnormalities. The sensitivity, specificity, and positive predictive value for lead failure in the presence of a LIA trigger were 87%, 99.5%, and 95.2%, respectively. Conclusions A positive LIA trigger in Biotronik Linox ICD-leads is highly predictive of lead failure. LIA is useful in ongoing surveillance of lead performance.

Arrhythmic sudden cardiac death (SCD) may be caused by ventricular tachycardia/fibrillation or pulseless electric activity/asystole. Effective risk stratification to identify patients at risk of arrhythmic SCD is essential for targeting our healthcare and research resources to tackle this important public health issue. Although our understanding of SCD because of pulseless electric activity/asystole is growing, the overwhelming majority of research in risk stratification has focused on SCD-ventricular tachycardia/ventricular fibrillation. This review focuses on existing and novel risk stratification tools for SCD-ventricular tachycardia/ventricular fibrillation. For patients with left ventricular dysfunction or myocardial infarction, advances in imaging, measures of cardiac autonomic function, and measures of repolarization have shown considerable promise in refining risk. Yet the majority of SCD-ventricular tachycardia/ventricular fibrillation occurs in patients without known cardiac disease. Biomarkers and novel imaging techniques may provide further risk stratification in the general population beyond traditional risk stratification for coronary artery disease alone. Despite these advances, significant challenges in risk stratification remain that must be overcome before a meaningful impact on SCD can be realized.

Frequent ventricular premature depolarizations (VPDs) can cause cardiomyopathy (CMP). The mechanisms underlying its development remain unclear, with VPD burden being only a weak predictor of risk.To determine whether VPD QRS duration at the time of initial presentation could predict risk for the subsequent development of CMP in patients with normal left ventricular ejection fraction (LVEF).From consecutive patients referred for ablation between January 1, 2006, and April 2, 2013, with ≥10% VPDs on 24-hour Holter monitoring, we identified 45 patients with normal LVEF and an electrocardiogram of the targeted VPD, who were then followed for at least 6 months (median 14 months; interquartile range [IQR] 8-32 months) before intervention. We excluded patients with structural or genetic heart disease.Of the 45 patients, 28 (62%) maintained normal LVEF and 17(38%) developed VPD-induced CMP. VPD burden was similar (26.5% [IQR 19.3%-39.5%] vs 26.0% [IQR 16.4%-41.0%]; P = 0.4) between the 2 groups. Patients who developed VPD-induced CMP had significantly longer VPD QRS duration (159 ms vs 142 ms; P.001) and a longer sinus QRS duration (97 ms vs 89 ms; P = .04). A VPD QRS duration of ≥153 ms best predicted development of VPD CMP (82% sensitivity and 75% specificity). Longer VPD QRS duration and a non-outflow tract site of VPD origin were independent risk factors for left ventricular dysfunction after multivariate analysis.VPD QRS duration longer than 153 ms and a non-outflow tract site of origin might be useful predictors of the subsequent development of VPD-induced CMP.

Aims The dynamic time course of entrance and exit block during pulmonary vein isolation (PVI) is unknown. The purpose of this series was to dynamically evaluate the manifestation of entrance and exit conduction block during simultaneous circumferential PVI. Methods and results Pacing manoeuvres were performed during cryoballoon ablation of left-sided pulmonary veins (PVs) in 30 consecutive patients with a history of drug-refractory paroxysmal atrial fibrillation. At the onset of ablation continuous pacing was performed from the PV at a cycle length of 600 ms until the appearance of exit block. Once exit block was demonstrated, uninterrupted pacing was immediately transitioned to the distal coronary sinus (CS) catheter and continued at 600 ms throughout the rest of the cryoapplication. The timing of exit block, entrance block, and corresponding cryoballoon temperature were noted for all patients. In the 45 PVs when real-time PV recordings were available during cryothermal ablation, the presence of exit block was reliably demonstrated to precede entrance block ( P < 0.0001) by a median of 5 s [interquartile range (IQR) 3, 12; median temperature at isolation −39°C (IQR −30, −45); nadir ablation temperature −53°C (IQR −48, −59)]. In all cases, when uninterrupted pacing was transitioned from the PV to the distal CS, entrance conduction from the left atrium to PV remained intact. Conclusion Circumferential PV ablation results in progressive PVI, beginning with unidirectional exit block, and followed by entrance block. As exit block reliably precedes entrance block, we are able to provide justification for the exclusive use of entrance conduction block as the endpoint of cryoballoon-based PVI.

Background Frequent ventricular premature depolarizations (VPDs) can cause reversible left ventricular (LV) dysfunction. However, not all patients normalize their LV function after VPD elimination. Objective To evaluate predictors of recovery of LV function following the elimination of frequent VPDs. Methods We identified patients with ≥10% VPDs/24 h and an LV ejection fraction of Results One hundred fourteen patients with ≥10% VPDs were identified; 66 had preserved and 48 had impaired LV function. Over a median follow-up of 10.6 months, 24 of 48 were classified as reversible and 13 of 48 as irreversible and 11 of 44 were excluded. There was a gradient of VPD QRS duration between the control, reversible, and irreversible groups (mean VPD QRS 135, 158, and 173 ms, respectively; P Conclusion In patients with LV dysfunction and frequent VPDs, we identified VPD QRS duration as the only independent predictor for the recovery of LV function after ablation. This suggests that VPD QRS duration may be a marker for the severity of underlying substrate abnormality.

The use of blanking periods, the immediate period postablation during which transient tachyarrhythmia episodes are not considered recurrences, has been predicated on the assumption that not all early recurrences of atrial tachyarrhythmias (ERAT) will lead to later recurrences and, as such, does not necessarily represent treatment failure. While ERAT can be expected to occur in approximately 38% of patients within the first 3 months of atrial fibrillation (AF) ablation, only half of these patients will manifest later recurrences. Clinical features related to the patient's history of AF, the index ablation procedure, and particularities of the ERAT can help identify patients at higher risk of later recurrence in whom aggressive attempts to control rhythm, including early cardioversion and reintervention, may be justified.

Further-more, the procedure is complex, time consuming, andhighly dependent on operator competency given the diffi-culties associated with creating contiguous curvilinear le-sions with focal ablation. As such, considerable effort hasbeen directed toward deriving more effective and saferapproaches.Balloon-based ablation systems potentially offer a sim-pler and faster means of achieving pulmonary vein isolation(PVI) that, theoretically, is less reliant on operator dexterity.Concurrently, cryothermal energy offers advantages overRF energy, including increased catheter stability, less endo-thelial disruption with lower thromboembolic risk, and min-imal tissue contraction with healing, an observation thoughtto result in less esophageal damage and PVS.