Ganesh S. Kamath

The utility of 12-lead Holter monitoring in patients with permanent atrial fibrillation for the identification of nonresponders after cardiac resynchronization therapy.

OBJECTIVES This study sought to determine the incidence of ineffective capture using 12-lead Holter monitoring and to assess whether this affects response to cardiac resynchronization therapy (CRT). BACKGROUND Cardiac resynchronization therapy is used in patients with atrial fibrillation (AF), prolonged QRS duration, and heart failure in the setting of ventricular dysfunction. The percentage of ventricular pacing is used as an indicator of adequate biventricular (BiV) pacing. Although device counters show a high pacing percentage, there may be ineffective capture because of underlying fusion and pseudo-fusion beats. METHODS We identified 19 patients (age 72 +/- 8 years, ejection fraction 18 +/- 5%), with permanent AF who underwent CRT. All patients received digoxin, beta-blockers, and amiodarone for rate control; device interrogation showed >90% BiV pacing. Patients had a 12-lead Holter monitor to assess the presence of effective (>90% fully paced beats/24 h) pacing. At 12 months post-CRT, the New York Heart Association functional class was reassessed and an echocardiogram was obtained and compared with pre-CRT. RESULTS Only 9 (47%) patients had effective pacing. The other 10 (53%) patients had 16.4 +/- 4.6% fusion and 23.5 +/- 8.7% pseudo-fusion beats. Long-term responders (> or =1 New York Heart Association functional class improvement) to CRT had a significantly higher percentage of fully paced beats (86.4 +/- 17.1% vs. 66.8 +/- 19.1%; p = 0.03) than nonresponders. CONCLUSIONS Pacing counters overestimate the degree of effective BiV pacing in patients with permanent AF undergoing CRT therapy. Only patients with complete capture responded clinically to CRT. These findings have important implications for the application of CRT to patients with permanent AF and heart failure.

Prevalence, Predictors, and Prognosis of Atrial Fibrillation Early After Pulmonary Vein Isolation: Findings from 3 Months of Continuous Automatic ECG Loop Recordings

Introduction: Following pulmonary vein isolation (PVI) for atrial fibrillation (AF), early recurrences are frequent, benign and classified as a part of a “blanking period.” This study characterizes early recurrences and determines implications of early AF following PVI.

Value of the Signal-Averaged Electrocardiogram in Arrhythmogenic Right Ventricular Cardiomyopathy/Dysplasia

BACKGROUND Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is an inherited disease that causes structural and functional abnormalities of the right ventricle (RV). The presence of late potentials as assessed by the signal-averaged electrocardiogram (SAECG) is a minor task force criterion. OBJECTIVE The purpose of this study was to examine the diagnostic and clinical value of the SAECG in a large population of genotyped ARVC/D probands. METHODS We compared the SAECGs of 87 ARVC/D probands (age 37 ± 13 years, 47 males) diagnosed as affected or borderline by task force criteria without using the SAECG criterion with 103 control subjects. The association of SAECG abnormalities was also correlated with clinical presentation, surface ECG, ventricular tachycardia (VT) inducibility at electrophysiologic testing, implantable cardioverter-defibrillator therapy for VT, and RV abnormalities as assessed by cardiac magnetic resonance imaging (cMRI). RESULTS Compared with controls, all three components of the SAECG were highly associated with the diagnosis of ARVC/D (P <.001). They include the filtered QRS duration (97.8 ± 8.7 ms vs 119.6 ± 23.8 ms), low-amplitude signal (24.4 ± 9.2 ms vs 46.2 ± 23.7 ms), and root mean square amplitude of the last 40 ms of the QRS (50.4 ± 26.9 μV vs 27.9 ± 36.3 μV). The sensitivity of using SAECG for diagnosis of ARVC/D was increased from 47% using the established 2 of 3 criteria (i.e., late potentials) to 69% by using a modified criterion of any 1 of 3 criteria, while maintaining a high specificity of 95%. Abnormal SAECG as defined by this modified criterion was associated with a dilated RV volume and decreased RV ejection fraction detected by cMRI (P <.05). SAECG abnormalities did not vary with clinical presentation or reliably predict spontaneous or inducible VT and had limited correlation with ECG findings. CONCLUSION Using 1 of 3 SAECG criteria contributed to increased sensitivity and specificity for the diagnosis of ARVC/D. This finding is incorporated in the recent modification of the task force criteria.

Long-Term Outcome of Leads and Patients Following Robotic Epicardial Left Ventricular Lead Placement for Cardiac Resynchronization Therapy

Introduction: In cardiac resynchronization therapy (CRT), positive clinical response and reverse remodeling have been reported using robotically assisted left ventricular (LV) epicardial lead placement. However, the long‐term performance of epicardial leads and long‐term outcome of patients who undergo CRT via robotic assistance are unknown. In addition, since the LV lead placement is more invasive than a transvenous procedure, it is important to identify patients at higher risk of complications.

The Role of Antiarrhythmic Drug Therapy for the Prevention of Sudden Cardiac Death

Sudden cardiac death (SCD) accounts for more than 300,000 deaths annually in the United States alone. The utility of antiarrhythmic drugs in survivors of SCD (secondary prevention) is limited because of their incomplete efficacy and long-term toxicity. Efforts to target primary prevention of SCD have focused on left ventricular dysfunction in conjunction with congestive heart failure. Antiarrhythmic drugs are not able to decrease mortality in this patient population either; in fact, certain drugs may actually increase overall mortality. In both primary and secondary prevention patients, only implantable cardioverter-defibrillator implantation is associated with improved survival. Antiarrhythmic drugs like azimilide, dofetilide, sotalol, and amiodarone can be used as adjunct treatment for management of atrial arrhythmias and to decrease implantable cardioverter-defibrillator shocks. There is an unmet need for more effective and less toxic antiarrhythmic medications.

Pulmonary Vein Isolation Alone in Patients with Persistent Atrial Fibrillation: An Ablation Strategy Facilitated by Antiarrhythmic Drug Induced Reverse Remodeling

PVI Alone in Patients with Persistent AF. Introduction: Pulmonary vein isolation (PVI) alone has been thought to be insufficient in patients with persistent atrial fibrillation (PersAF). We hypothesized that preablation treatment of PersAF with a potent antiarrhythmic drug (AAD) would facilitate reverse atrial remodeling and result in high procedural efficacy after PVI alone.

Computational Method to Predict Esophageal Temperature Elevations During Pulmonary Vein Isolation

Background:  The esophagus is in close proximity to the posterior wall of the left atrium, which renders it susceptible to thermal injury during radiofrequency (RF) ablation procedures for atrial fibrillation (AF). Real‐time assessment of esophageal position and temperature (T °) during pulmonary vein (PV) isolation has not been extensively explored.