Faculty Bibliography

One of the currently accepted paradigms for catheter ablation of persistent atrial fibrillation (AF) is wide antral pulmonary vein isolation, followed by some combination of adjunctive ablation that may include, but is not limited to, linear left atrial ablation, complex fractionated atrial electrogram ablation, rotor ablation, and box isolation of fibrosis until sinus rhythm is restored1-3 . These lesion sets often include establishment of perimitral conduction block, either as an empiric linear ablation, or to terminate and prevent perimitral flutter

AIMS: In patients presenting with spontaneous sustained ventricular tachycardia (VT) from the outflow-tract region without overt structural heart disease ablation may target premature ventricular contractions (PVCs) when VT is not inducible. We aimed to determine whether inducibility of VT affects ablation outcome. METHODS AND RESULTS: Data from 54 patients (31 men; age, 52 +/- 13 years) without overt structural heart disease who underwent catheter ablation for symptomatic sustained VT originating from the right- or left-ventricular outflow region, including the great vessels. A single morphology of sustained VT was inducible in 18 (33%, SM group) patients, and 11 (20%) had multiple VT morphologies (MM group). VT was not inducible in 25 (46%) patients (VTni group). After ablation, VT was inducible in none of the SM group and in two (17%) patients in the MM group. In the VTni group, ablation targeted PVCs and 12 (48%) patients had some remaining PVCs after ablation. During follow-up (21 +/- 19 months), VT recurred in 46% of VTni group, 40% of MM inducible group, and 6% of the SM inducible group (P = 0.004). Analysis of PVC morphology in the VTi group further supported the limitations of targeting PVCs in this population. CONCLUSION: Absence of inducible VT and multiple VT morphologies are not uncommon in patients with documented sustained outflow-tract VT without overt structural heart disease. Inducible VT is associated with better outcomes, suggesting that attempts to induce VT to guide ablation are important in this population.

BACKGROUND: The initial impedance decrease during radiofrequency (RF) ablation is an indirect marker of catheter contact and lesion formation. We aimed to assess feasibility, efficacy, and safety of an ablation approach guided by initial impedance decrease. METHODS: A total of 25 patients with paroxysmal AF had point-by-point, wide antral pulmonary vein (PV) isolation. RF applications were aborted if a decrease of at least 5 Omega did not occur in the first 10 seconds; otherwise, ablation was continued for at least 20 seconds. Power was 30 Watts and reduced to 15-25 Watts on the posterior wall. RESULTS: A total of 28% of RF applications were terminated because of inadequate impedance decrease. The remaining lesions showed a median decrease of 7.6 Omega (IQR 5.0-10.7) at 10 seconds and median duration of RF lesions was 38 seconds. Note that, 100 PVs were isolated with 49 rings. PVI occurred before anatomic completion of the ablation ring of adequate lesions in 39/49 (80%) and concurrent with ring completion in 7/49 (14%). Additional lesions were required in 3/49 (6%) rings. After PVI, additional lesions were required to eliminate dormant conduction in 2/47 (4%) and pace-capture on the ablation line in 24/49 vein pairs (49%). During short-term follow-up, 3 nonfatal esophageal injuries and 2 late pericardial effusions occurred. During a mean follow-up of 431 +/- 87 days, 21/25 patients (84%) remained free of recurrent symptomatic atrial arrhythmias. CONCLUSIONS: PVI guided by initial impedance decrease is feasible and results in PVI concurrent with or before completion of the ablation ring in 94% of patients. Single procedure efficacy after one year of follow-up was 84%. Near-term complications suggest that deeper lesions are created, indicating that further reduction of RF-power and duration is warranted.

BACKGROUND: Ventricular arrhythmias (VAs) from the left ventricular outflow tract (LVOT) region can be inaccessible for ablation because of epicardial fat or overlying coronary arteries. OBJECTIVE: We describe surgical cryoablation of this type of VA. METHODS: From March 2009 to 2014, 190 consecutive patients with VAs originating from the LVOT underwent ablation at our institution. Four patients (2%) underwent surgical cryoablation for highly symptomatic VAs after failing catheter ablation. RESULTS: In all patients, endocardial or percutaneous epicardial mapping was consistent with origin in the LVOT. In 2 patients, the points of earliest activation during VAs were marked with a bipolar pacing lead in the overlying cardiac vein for guidance during surgery. Surgical cryoablation was successful in 3 of the 4 patients. The fourth patient subsequently had successful endocardial catheter ablation. During a mean follow-up of 22 +/- 16 months (range 4-42 months), all patients showed abolition of or marked reduction in symptomatic VA. However, 1 patient subsequently required percutaneous intervention to the left anterior descending coronary artery; another developed progressive left ventricular systolic dysfunction caused by nonischemic cardiomyopathy; and a third patient underwent permanent pacemaker implantation because of complete atrioventricular block after concomitant aortic valve replacement. CONCLUSION: Surgical cryoablation is an option for highly symptomatic drug-resistant VAs emanating from the LVOT region. Despite extensive preoperative mapping, the procedure is not effective for all patients, and coronary injury is a risk.

BACKGROUND: Cardiac sarcoid-related ventricular tachycardia (VT) is a rare disorder; the underlying substrate and response to ablation are poorly understood. We sought to examine the ventricular substrate and outcomes of catheter ablation in this population. METHODS AND RESULTS: Of 435 patients with nonischemic cardiomyopathy referred for VT ablation, 21 patients (5%) had cardiac sarcoidosis. Multiple inducible VTs were observed with mechanism consistent with scar-mediated re-entry in all VTs. Voltage maps showed widespread and confluent right ventricular scarring. Left ventricular scarring was patchy with a predilection for the basal septum, anterior wall, and perivalvular regions. Epicardial right ventricular scar overlay and exceeded the region of corresponding endocardial scar. After >/=1 procedures, ablation abolished >/=1 inducible VT in 90% and eliminated VT storm in 78% of patients; however, multiple residual VTs remained inducible. Failure to abolish all inducible VTs was because of septal intramural circuits or extensive right ventricular scarring. Multiple procedure VT-free survival was 37% at 1 year, but VT control was achievable in the majority of patients with fewer antiarrhythmic drugs compared with preablation (2.1+/-0.8 versus 1.1+/-0.8; P<0.001). CONCLUSIONS: Patients with cardiac sarcoidosis and VT exhibit ventricular substrate characterized by confluent right ventricular scarring and patchy left ventricular scarring capable of sustaining a large number of re-entrant circuits. Catheter ablation is effective in terminating VT storm and eliminating >/=1 inducible VT in the majority of patients, but recurrences are common. Ablation in conjunction with antiarrhythmic drugs can help palliate VT in this high-risk population.

BACKGROUND: Entrainment can be useful for mapping atrial tachycardias (ATs) after atrial fibrillation (AF) ablation but may result in AT alteration or termination. OBJECTIVE: We aimed to determine the incidence and risk factors for AT alteration or termination. METHODS: In 30 consecutive patients, 62 ATs (mean cycle length [CL] 268 +/- 53 ms) in which overdrive pacing for entrainment mapping was performed were retrospectively analyzed. AT was classified as altered if the CL or activation pattern remained altered 10 seconds after pacing. The variability in the PP intervals was determined over 10 beats from 2 measures: (1) the difference between the shortest and the longest CL expressed as a percentage of the CL and (2) the mean difference between sequential PP intervals expressed as a percentage of the AT CL (CLDmean). RESULTS: Of 386 total pacing attempts (tachycardia CL [TCL] - pacing CL [PCL] difference 15 +/- 6 ms), 5 (1.3%) altered or terminated AT and 381 did not change AT (98.7%). When the T

BACKGROUND: Strategies for prevention of sudden cardiac death focus on severe left ventricular (LV) dysfunction, although most sudden cardiac death postmyocardial infarction occurs in patients with mild/moderate LV dysfunction. We tested the hypothesis that infarct heterogeneity by cardiac magnetic resonance is associated with mortality beyond LV ejection fraction (LVEF) in patients with coronary artery disease and LV dysfunction. In addition, we examined the association between infarct heterogeneity and mortality in those with LVEF >35%. METHODS AND RESULTS: We studied 301 patients with coronary artery disease and LV dysfunction referred for cardiac magnetic resonance. We quantified total infarct mass, infarct core mass, and peri-infarct zone (PIZ) normalized for total infarct mass (%PIZ) using signal-intensity criteria of >2 SDs, >3 SDs, and 2- to -3 SDs above remote myocardium, respectively. Mean LVEF was 41 +/- 14%. After 3.9 years median follow-up, 66 (22%) patients died (13 sudden cardiac death; 33 with LVEF >35%). In patients with LVEF >35%, below-median %PIZ carried an annual death rate of 2.8% versus 12% in patients with above-median %PIZ (P<0.001). In a multivariable model, %PIZ maintained strong association with mortality adjusted to patient age, LVEF, right ventricular ejection fraction, prolonged QT interval, and total infarct size and resulted in improve risk reclassification 0.492 (95% confidence interval, 0.183-0.817). CONCLUSIONS: Cardiac magnetic resonance infarct heterogeneity has a strong association with mortality independent of LVEF in patients with coronary artery disease and LV dysfunction, particularly in patients with mild or moderate LV dysfunction. Further studies incorporating cardiac magnetic resonance in clinical decision making for defibrillator therapy are warranted.

BACKGROUND: Catheter ablation for ventricular tachycardia (VT) from structural heart disease has a significant risk of recurrence, but the optimal duration for in-hospital monitoring is not defined. This study assesses the timing, correlates, and prognostic significance of early VT recurrence after ablation. METHODS AND RESULTS: Of 370 patients (313 men; aged 63.0+/-13.2 years) who underwent a first radiofrequency ablation for sustained monomorphic VT associated with structural heart disease from 2008 to 2012, sustained VT recurred in 81 patients (22%) within 7 days. In multivariable analysis, early recurrence was associated with New York Heart Association classification >/=III (odds ratio [OR] 1.90, 95% confidence interval [CI] 1.03-3.48; P=0.04), dilated cardiomyopathy (OR 1.93, 95% CI 1.03-3.57; P=0.04), prevalence of VT storm before the procedure (OR 2.62, 95% CI 1.48-4.65; P=0.001), a greater number of induced VTs (OR 1.24, 95% CI 1.07-1.45; P=0.006), and acute failure or no final induction test (OR 1.88, 95% CI 1.03-3.40; P=0.04). During a median of 2.5 (1.2, 4.0) years of follow-up, early VT recurrence was an independent correlates of mortality (hazard ratio 2.59, 95% CI 1.52-4.34; P=0.0005). CONCLUSIONS: Patients who have early recurrences of VT after ablation are a high risk group who may be identifiable from their clinical profile. Further study is warranted to define the optimal treatment strategies for this patient group.