Safety and efficacy of an intrinsic antitachycardia pacing algorithm in patients from Japan and South Korea: results from a cardiac device registry in the Asia Pacific region.

Background: Antitachycardia pacing (ATP) therapy, available in modern implantable cardioverter defibrillators (ICD) and cardiac resynchronization therapy defibrillators (CRT-D), aims to terminate ventricular arrhythmias without administering high energy shocks. The intrinsic ATP (iATP) algorithm automates ATP programming in real-time, tailoring therapy based on previous ATP attempts. This study evaluated the safety, efficacy, and clinical outcomes of iATP in patients from Japan and South Korea.

Methods: This study was a prospective, observational, multi-site registry that enrolled patients from Japan and South Korea implanted with an ICD or CRT-D device with the iATP algorithm. Patients were followed for a minimum of 12 months. Outcomes included ATP termination success, appropriate shocks, acceleration, arrhythmia-related syncope, and mortality. A post hoc unanchored matching-adjusted indirect comparison (uMAIC) was performed to compare iATP with standard ATP using published literature.

Results: A total of 800 patients were enrolled. The iATP success rate for terminating all episodes was 89.2% (86.2% Generalized Estimating Equation [GEE] estimated) and 82.2% for episodes in the fast VT zone (80.9% GEE estimated). Acceleration occurred in 2.0% of episodes, and arrhythmia-related syncope was observed in 0.5% of patients. The 1-year survival rate was 96.1%, with no device-related deaths or abnormal battery depletions. The uMAIC showed iATP had higher termination efficacy across all episodes (88.1% vs. 79.3%,  < 0.001), a lower probability of appropriate shocks per episode (iATP 14.7% and ATP 31.3%,  < 0.001), and fewer accelerations per episode (2.1% vs. 4.8%,  = 0.02), with similar probability of arrhythmia-related syncope per patient (0.5% vs 0.9%,  = 0.35) and mortality (12-month Kaplan Meyer survival estimate iATP 95.4%, ATP 95.3%,  = 0.43).

Conclusions: iATP exhibited a high ventricular arrhythmia termination efficacy and a favorable safety profile. Comparison of iATP to standard ATP provides initial evidence of higher termination success, lower incidence of accelerations and appropriate shocks, and similar rates of mortality and arrhythmia-related syncope.

Trial Registration: ClinicalTrials.gov Identifier: NCT01524276; Japan Registry of Clinical Trials Identifier: jRCT1042200049.