Ventricular antitachycardia pacing therapy in patients with heart failure implanted with a cardiac resynchronization therapy defibrillator device: Efficacy, safety, and impact on mortality

Background Cardiac resynchronization therapy defibrillator can terminate ventricular tachycardia (VT) and fast VT (FVT) via antitachycardia pacing (ATP). Objectives We evaluated efficacy and safety of ATP, whether ATP induces ventricular arrhythmias after inappropriate ATP or atrial fibrillation (AF) after appropriate ATP, and whether ATP is associated with mortality. Methods A total of 1404 patients with a cardiac resynchronization therapy defibrillator were followed in a prospective multicenter observational research. All-cause mortality rates were estimated in patient subgroups in order to uncouple the trigger (VT/FVT or other rhythms causing inappropriate detections) from ATP therapy. Results Over a median follow-up of 31 months, 2938 VT/FVT episodes were treated with ATP in 360 patients. The adjusted ATP success rate was 63% (95% confidence interval [CI] 57%-69%) on FVTs and 68% (95% CI 62%-74%) on VTs. Acceleration occurred in 55 (1.87%) and syncope in 4 (0.14%) of all ATP-treated episodes. In 14 true VT/FVT episodes in 5 patients, AF followed ATP therapy. In 4 episodes in 2 patients, VT followed ATP inappropriately applied during AF. Death rate per 100 patient-years was 5.6 (95% CI 4.3-7.5) in patients with appropriate ATP and 1.5 (95% CI 0.4-6.1) in patients with inappropriate ATP (P =.045). Conclusion ATP was effective in terminating VT/FVT episodes and displayed a good safety profile. ATP therapies by themselves did not increase death risk; prognosis was indeed better in patients without arrhythmic episodes, even if they received inappropriate ATP, than in patients with ATP on VT/FVT episodes. Adverse outcomes observed in patients receiving implantable cardioverter-defibrillator therapies are probably related to the arrhythmia itself, a marker of disease progression, rather than to adverse effects of ATP.