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Background: Ventricular tachyarrhythmias and sudden cardiac death show a circadian pattern of occurrence in patients with heart failure. In the rodent ventricle, a significant portion of genes, including some ion channels, shows a circadian pattern of expression. However, genes that define electrophysiological properties in failing human heart ventricles have not been examined for a circadian expression pattern.Methods: Ventricular tissue samples were collected from patients at the time of cardiac transplantation. Two sets of samples (n=37 and 46, one set with a greater arrhythmic history) were selected to generate pseudo-time series according to their collection time. A third set (n=27) of samples was acquired from the nonfailing ventricles of brain-dead donors. The expression of 5 known circadian clock genes and 19 additional ion channel genes plausibly important to electrophysiological properties were analyzed by real-time polymerase chain reaction and then analyzed for the percentage of expression variation attributed to a 24-hour circadian pattern.Results: The 5 known circadian clock gene transcripts showed a strong circadian expression pattern. Compared with rodent hearts, the human circadian clock gene transcripts showed a similar temporal order of acrophases but with a ≈7.6 hours phase shift. Five of the ion channel genes also showed strong circadian expression. Comparable studies of circadian clock gene expression in samples recovered from nonheart failure brain-dead donors showed acrophase shifts, or weak or complete loss of circadian rhythmicity, suggesting alterations in circadian gene expression.Conclusions: Ventricular tissue from failing human hearts display a circadian pattern of circadian clock gene expression but phase-shifted relative to rodent hearts. At least 5 ion channels show a circadian expression pattern in the ventricles of failing human hearts, which may underlie a circadian pattern of ventricular tachyarrhythmia/sudden cardiac death. Nonfailing hearts from brain-dead donors show marked differences in circadian clock gene expression patterns, suggesting fundamental deviations from circadian expression. [ABSTRACT FROM AUTHOR]

Background: The mechanisms by which persistent atrial fibrillation (AF) terminates via localized ablation are not well understood. To address the hypothesis that sites where localized ablation terminates persistent AF have characteristics identifiable with activation mapping during AF, we systematically examined activation patterns acquired only in cases of unequivocal termination by ablation.Methods and Results: We recruited 57 patients with persistent AF undergoing ablation, in whom localized ablation terminated AF to sinus rhythm or organized tachycardia. For each site, we performed an offline analysis of unprocessed unipolar electrograms collected during AF from multipolar basket catheters using the maximum -dV/dt assignment to construct isochronal activation maps for multiple cycles. Additional computational modeling and phase analysis were used to study mechanisms of map variability. At all sites of AF termination, localized repetitive activation patterns were observed. Partial rotational circuits were observed in 26 of 57 (46%) cases, focal patterns in 19 of 57 (33%), and complete rotational activity in 12 of 57 (21%) cases. In computer simulations, incomplete segments of partial rotations coincided with areas of slow conduction characterized by complex, multicomponent electrograms, and variations in assigning activation times at such sites substantially altered mapped mechanisms.Conclusions: Local activation mapping at sites of termination of persistent AF showed repetitive patterns of rotational or focal activity. In computer simulations, complete rotational activation sequence was observed but was sensitive to assignment of activation timing particularly in segments of slow conduction. The observed phenomena of repetitive localized activation and the mechanism by which local ablation terminates putative AF drivers require further investigation. [ABSTRACT FROM AUTHOR]

Background: The VANISH trial (Ventricular Tachycardia Ablation Versus Escalated Antiarrhythmic Drug Therapy in Ischemic Heart Disease) compared the effectiveness of escalated antiarrhythmic drug therapy to catheter ablation in patients with prior myocardial infarction, an implanted defibrillator, and ventricular tachycardia (VT). The effectiveness of these interventions in patients on sotalol versus amiodarone was compared.Methods and Results: Analysis was conducted based on whether patients had recurrent VT, despite amiodarone (amio-refractory) or nonamiodarone drugs (sotalol-refractory). Outcomes included death, VT storm, appropriate implantable cardioverter defibrillator shock, and any ventricular arrhythmia. At baseline, 169 (65.2%) were amio-refractory, and 90 (34.7%) were sotalol-refractory (1 patient on procainamide rather than sotalol). Amio-refractory patients had more renal insufficiency (23.7% versus 10%; P=0.0008), worse New York Heart Association class (82.3% II/III versus 65.5%; P=0.0003), and lower ejection fraction (29±9.7% versus 35.2±11%; P<0.0001). Within the amio-refractory group, ablation resulted in reduction of any ventricular arrhythmia compared with escalated drug therapy (hazard ratio, 0.53; 95% confidence interval, 0.31-0.9), P=0.020). Sotalol-refractory patients had trends toward higher mortality and VT storm with ablation, with no effect on implantable cardioverter defibrillator shocks. Within the escalated drug therapy arm, amio-refractory patients had a higher rate of the composite outcome (hazard ratio, 1.94; 95% confidence interval, 1.14-3.29; P=0.0144) and a trend to higher mortality (hazard ratio, 2.40; 95% confidence interval, 0.93-6.22; P=0.07), whereas mortality was not different between amio- and sotalol-refractory patients within the ablation treatment group.Conclusions: Patients with amio-refractory VT have a higher rate of ventricular arrhythmia and mortality than those with sotalol-refractory VT and derive greater benefit of catheter ablation than for patients with sotalol-refractory VT who are switched to amiodarone.Clinical Trial Registration: URL: https://clinicaltrials.gov. Unique identifier: NCT00905853. [ABSTRACT FROM AUTHOR]