Aims Complications from catheter ablation for atrial fibrillation (AF) are well described. Changing aspects of AF ablation including patient populations referred, institutional experience, and emerging catheter and pharmacological options may impact complication rates. We assessed procedural complication trends in AF ablation patients from 2003‐2015 to identify what factors affect adverse event rates. Methods and results We evaluated consecutively enrolled patients undergoing initial AF ablation from 2003 through 2015. Statistical analyses were performed to identify predictors of increased risk for major complications, which were defined as death, stroke, atrio‐oesophageal fistula, phrenic nerve injury, cardiovascular events requiring blood transfusions or procedural interventions, or non‐cardiovascular events requiring intervention. A total of 1475 patients (mean age 59.5 ± 10.5, 82% male) were evaluated. Major complications occurred in 3.9% (n = 58) of cases, including vascular access‐site haematoma (1.3%), cardiac tamponade (1.1%), and cerebrovascular accident (CVA) (0.9%). Univariate analysis revealed increased risk of complications associated with hypertension (P = 0.048), CHA2DS2VASc score ≥1 (P = 0.015), and early institutional experience (P = 0.003). Populations with higher CHA2DS2VASc scores underwent AF ablation more frequently over time (P < 0.001). Novel catheters and anticoagulants did not appreciably affect complication rates. Multivariate analysis adjusting for hypertension, CHA2DS2VASc score, and institutional experience showed that higher CHA2DS2VASc score and early institutional experience were independent predictors of adverse events. Conclusion Patient characteristics reflected in CHA2DS2VASc scoring and early institutional experience predict increased complication rates following AF ablation. Despite more patients with higher CHA2DS2VASc scores undergoing AF ablation, complication rates fell over time as institutional experience increased.

Introduction: Mounting evidence suggests that left atrial (LA) structural remodeling plays an important role in the mechanism of stroke in patients with a history of atrial fibrillation (AF). We evaluated the association among the severity of LA abnormality on electrocardiogram (ECG), the severity of LA structural remodeling by cardiac magnetic resonance (CMR), and a history of stroke or transient ischemic attack in patients with AF referred for catheter ablation. Methods: A total of 229 consecutive patients (age 60±10 years, 72% male) referred for catheter ablation of AF who were in sinus rhythm at the time of pre-ablation ECG recording and CMR were included, with (n=21; the stroke group) and without (n=208; control group) a history of stroke or TIA. The severity of LA abnormality on ECG was quantified from the P wave terminal force in lead V 1 (PTFV 1 ). Results: In the stroke group, PTFV 1 was significantly higher compared with the control group (8,107±5,921 vs. 4,865±3,205μV*ms; p 2 ) and decrease in left ventricular ejection fraction (%) were associated with an increase in PTFV 1 (47.7 and 74,1μV*ms; p=0.027 and 0.005, respectively). Multivariable analysis demonstrated that the PTFV 1 and LA emptying fraction were associated with a history of stroke (odds ratio 1.23 and 0.94; p=0.002 and 0.037, respectively) after adjusting for the CHA 2 DS 2 -VASc score and the LA minimum volume. Conclusions: PTFV 1 is an independent marker of stroke, and provides an incremental value to the CHA 2 DS 2 -VASc score in patients with AF. Evaluation of LA abnormalities by 12-lead ECG may improve the current risk stratification of stroke in patients with AF.

OBJECTIVES The aims of this study were to: 1) use a novel method of late gadolinium enhancement (LGE) quantification that uses normalized intensity measures to confirm the association between LGE extent and atrial fibrillation (AF) recurrence following ablation; and 2) examine the presence of interaction and effect modification between LGE and AF persistence.BACKGROUND Recurrent AF after catheter ablation has been reported to associate with the baseline extent of left atrial LGE on cardiac magnetic resonance. Traditional methods for measurement of intensity lack an objective threshold for quantification and interpatient comparisons of LGE.METHODS The cohort included 165 participants (mean age 60.0 +/- 10.2 years, 77% men, 57% with persistent AF) who underwent initial AF ablation. The association of baseline LGE extent with AF recurrence was examined using multivariable Cox proportional hazards models. Multiplicative and additive interactions between AF type and LGE extent were examined.RESULTS During 10.2 +/- 5.7 months of follow-up, 63 patients (38.2%) experienced AF recurrence. Baseline LGE extent was independently associated with AF recurrence after adjusting for confounders (hazard ratio: 1.5 per 10% increased LGE; p < 0.001). The hazard ratio for AF recurrence progressively increased as a function of LGE. The magnitude of association between LGE >35% and AF recurrence was greater among patients with persistent AF (hazard ratio: 6.5 [p = 0.001] vs. 3.6 [p = 0.001]); however, there was no evidence for statistical interaction.CONCLUSIONS Regardless of AF persistence at baseline, participants with LGE 35% have favorable outcomes, whereas those with LGE >35% have a higher rate of AF recurrence in the first year after ablation. These findings suggest a role for: 1) patient selection for AF ablation using LGE extent; and 2) substrate modification in addition to pulmonary vein isolation in patients with LGE extent exceeding 35% of left atrial myocardium. (C) 2016 by the American College of Cardiology Foundation.

BACKGROUND:Symptomatic left atrial (LA) flutter (LAFL) is common after atrial fibrillation (AF) ablation. OBJECTIVE:The purpose of this study was to examine the association of baseline LA function with incident LAFL after AF ablation. METHODS:The source cohort included 216 patients with cardiac magnetic resonance (CMR) before initial AF ablation between 2010 and 2013. Patients who underwent cryoballoon or laser ablation, patients with AF during CMR, and those with suboptimal CMR, or missing follow-up data were excluded. Baseline LA volume and function were assessed by feature-tracking CMR analysis. RESULTS:The final cohort included 119 patients (mean age 58.9 ± 11 years; 76.5% men; 70.6% patients with paroxysmal AF). During a median follow-up of 421 days (interquartile range 235-751 days), 22 patients (18.5%) had incident LAFL. Baseline LA volume was similar between the 2 groups. In contrast, baseline reservoir, conduit, and contractile function of the LA were significantly impaired in patients with incident LAFL. Baseline global peak longitudinal atrial strain (PLAS) <22.65% predicted incident LAFL with 86% sensitivity and 68% specificity (C statistic 0.76). In a multivariable model adjusting for age, heart failure, and LA volume, PLAS (hazard ratio 0.9 per % increase in PLAS; P = .003) and LA linear lesions (hazard ratio 2.94; P = .020) were independently associated with incident LAFL. The coexistence of PLAS <22.65% and linear lesions was associated with 9-fold increased hazard of incident LAFL. CONCLUSION:Baseline LA function and linear lesions were independently associated with incident LAFL after AF ablation. Linear lesions should be limited to selected cases, especially in patients with impaired LA function.

Background: Pulmonary vein (PV) isolation is commonly used for treatment of drug-refractory symptomatic atrial fibrillation (AF). Previous studies have reported contradictory results regarding the association of PV structure and AF recurrence following ablation. We sought to examine the association of PV diameter with AF recurrence following ablation. Methods: We conducted a retrospective cohort study of 132 patients with AF that had undergone initial PV isolation. Cardiac magnetic resonance angiography was performed prior to ablation, and pulmonary vein and left atrial dimensions were measured. In the presence of a left common PV trunk, the diameter of the superior vein branch was measured after the ostium. Recurrence of AF was documented using scheduled (6 and 12 months) and symptom-prompted electrocardiography. Results: The average age was 59.7±9.8 years. Of all patients 78.8% were male, 88.6% were Caucasian, and 45.5% had persistent AF. Atrial fibrillation recurrence was noted in 48 (36%) of patients at 1 year. Due to significant co-linearity among PV diameters within the same individual, the left superior PV (LSPV) diameter was used as a surrogate for all veins. In a multivariable Cox proportional hazards model adjusting for left atrial volume, AF persistence, age, and gender, LSPV diameter > 90 th percentile (22 mm) was independently associated with AF recurrence (Figure, Hazard Ratio 1.89 ± 0.57, p=0.035). Conclusion: Increased PV diameter is associated with AF recurrence following PV isolation. Tools to improve the efficiency and permanence of electrical isolation for large diameter PVs will likely improve procedural efficacy. Figure. The hazard ratio plot demonstrates that as the LSPV diameter increases, the hazard ratio of AF recurrence after PVI increases.

Introduction: CIED (pacemaker (PPM) or defibrillator (ICD)) analysis is recommended upon death but there is no data upon the role of systematic CIED analysis at autopsy. We undertook a registry analysis to determine the utility of pre-specified CIED explantation, interrogation and technical analysis at autopsy . Methods: From May 19, 2009 - May 18, 2014 adult & pediatric autopsy subjects at two academic institutions underwent concomitant CIED pulse generator explantation. The autopsy report was reviewed and the CIED was interrogated by an electrophysiologist (EP) for relevant clinical alerts and submitted to the applicable manufacturer for technical analysis. Significant alerts were reviewed & confirmed by a 2 nd EP. Results: Seventy (4.3%) of 1642 autopsies had CIEDs and underwent either complete (90%) or limited autopsy. There were 30 PPMs and 40 ICDs (4 manufacturers). The mean age at death was 62.7 years (range 6 months - 97 years). In total, 35 (50%) died suddenly and 35 died non-suddenly. Significant clinical alerts were found in 22/35 (62.9%) sudden death subjects and included; 10 sustained VT/VF episodes terminated with either internal or external shocks, 10 sustained VT/VF episodes not terminated due to: undersensing (3), unsuccessful shock (2), rate below ICD therapy cut-off (1), or sustained VT/VF detection in PPM recipient (4). 4 (2 with VT/VF) exhibited an intra-thoracic impedance derived fluid index > 200. In the non-sudden death group 7/35 (20%) displayed a significant clinical alert; 2 sustained VT/VF episodes and 6 (1 with VT/VF) exhibited a fluid index > 200. There was significant association between likelihood of clinical alert and sudden death as compared to non-sudden death (χ 2 = 11.538, p 2 = 15.006, p Conclusion: CIED analysis is an important post-mortem diagnostic tool and should be routinely performed at the time of autopsy. Post-mortem CIED analysis is especially useful in cases of sudden death to screen for significant clinical alerts and to rule out component failure.

CRT benefits those patients with advanced heart failure with LV conduction delay as measured by QRS duration (QRSd). An increase in QRSd, however, may result from a combination of electrical delay and mass effect from LV dilation. This balance may be variable such that patients with a small LV and a

Introduction: Feasibility of post-mortem CIED (pacemaker (PPM) or defibrillator (ICD)) retrieval for reuse has recently been shown but a model for systematic post-mortem CIED acquisition remains elusive. Prior studies of CIED longevity in retrospective autopsy and funeral home & crematory series have indicated a low yield of usable devices (21 - 30%). However, processes for timely interrogation and reprogramming were not in place. We undertook a registry analysis to determine estimated longevities and reuse potential upon routine CIED retrieval at autopsy. Methods: From May 19, 2009 - May 18, 2014 adult & pediatric autopsy subjects at two academic institutions underwent concomitant CIED pulse generator explantation. The CIED was interrogated by an electrophysiologist, device longevity was cataloged and the device submitted to the applicable manufacturer for formal technical analysis. Results: Seventy (4.3%) of 1642 autopsies had CIEDs. All were retrieved and interrogated within a mean 18.4 ± 14.1 days. There were 30 PPMs and 40 ICDs (4 manufacturers). CIEDs had been implanted for a mean of 2.7 ± 2.4 years and 22/70 (31.4%) had been implanted < 1 year prior to death. Overall, 12/70 CIEDs (17.1%) had a longevity < 1 year (including 5 at elective replacement indication (ERI), 1 recalled PPM, and 1 ICD hard reset), 20/70 (28.6%) had a longevity 1 - < 4 years, and 38/70 (54.3%) had longevity ≥ 4 years. This last group demonstrated a mean longevity of 7.1 ± 2.3 years. Manufacturer technical analyses helped to confirm device longevity status and functionality, identify premature battery depletion, and confirm non-reprogrammable hard reset (due to cold exposure). Conclusion: In contrast to prior studies, our registry analysis demonstrated that the majority of CIEDs retain considerable device longevity and functionality when promptly evaluated post-mortem. Such a systematic approach represents a practical model for post-mortem CIED retrieval, evaluation and potential reuse.

Phrenic Nerve InjuryIntroductionPhrenic nerve injury (PNI) is a well-known, although uncommon, complication of pulmonary vein isolation (PVI) using radiofrequency energy. Currently, there is no consensus about how to avoid or minimize this injury. The purpose of this study was to determine how often the phrenic nerve, as identified using a high-output pacing, lies along the ablation trajectory of a wide-area circumferential lesion set. We also sought to determine if PVI can be achieved without phrenic nerve injury by modifying the ablation lesion set so as to avoid those areas where phrenic nerve capture (PNC) is observed.Methods and ResultsWe prospectively enrolled 100 consecutive patients (age 61.7 9.2 years old, 75 men) who underwent RF PVI using a wide-area circumferential ablation approach. A high-output (20 mA at 2 milliseconds) endocardial pacing protocol was performed around the right pulmonary veins and the carina where a usual ablation lesion set would be made. A total of 30% of patients had PNC and required modification of ablation lines. In the group of patients with PNC, the carina was the most common site of capture (85%) followed by anterior right superior pulmonary vein (RSPV) (70%) and anterior right inferior pulmonary vein (RIPV) (30%). A total of 25% of PNC group had capture in all 3 (RSPV, RIPV, and carina) regions. There was no difference in the clinical characteristics between the groups with and without PNC. RF PVI caused no PNI in either group.ConclusionHigh output pacing around the right pulmonary veins and the carina reveals that the phrenic nerve lies along a wide-area circumferential ablation trajectory in 30% of patients. Modification of ablation lines to avoid these sites may prevent phrenic nerve injury during RF PVI.

Recent trial data suggest that responses to cardiac resynchronization therapy (CRT) differ amongst subgroups. Less wide QRS duration and non-left bundle branch block (non-LBBB) morphologies have been associated with less robust response. However, the prevalence, baseline characteristics,

The vast majority of patients included in studies looking at the effect of reverse ventricular remodeling on survival following cardiac resynchronization therapy (CRT) have had a left bundle branch block (LBBB). Whether reverse remodeling predicts improved long term survival in patients with a non-