Background-Successful antitachycardia pacing (ATP) terminates ventricular tachycardia (VT) up to 250 bpm without the need for painful shocks in implantable cardioverter-defibrillator (ICD) patients. Fast VT (FVT) Ͼ200 bpm is often treated by shock because of safety concerns, however. This prospective, randomized, multicenter trial compares the safety and utility of empirical ATP with shocks for FVT in a broad ICD population. Methods and Results-We randomized 634 ICD patients to 2 arms-standardized empirical ATP (nϭ313) or shock (nϭ321)-for initial therapy of spontaneous FVT. ICDs were programmed to detect FVT when 18 of 24 intervals were 188 to 250 bpm and 0 of the last 8 intervals were Ͼ250 bpm. Initial FVT therapy was ATP (8 pulses, 88% of FVT cycle length) or shock at 10 J above the defibrillation threshold. Syncope and arrhythmic symptoms were collected through patient diaries and interviews. In 11Ϯ3 months of follow-up, 431 episodes of FVT occurred in 98 patients, representing 32% of ventricular tachyarrhythmias and 76% of those that would be detected as ventricular fibrillation and shocked with traditional ICD programming. ATP was effective in 229 of 284 episodes in the ATP arm (81%, 72% adjusted). Acceleration, episode duration, syncope, and sudden death were similar between arms. Quality of life, measured with the SF-36, improved in patients with FVT in both arms but more so in the ATP arm. Conclusions-Compared with shocks, empirical ATP for FVT is highly effective, is equally safe, and improves quality of life. ATP may be the preferred FVT therapy in most ICD patients.

Background-Implantable cardioverter-defibrillators (ICDs) can terminate some ventricular tachycardias (VTs) painlessly with antitachycardia pacing (ATP). ATP has not routinely been applied for VT Ͼ188 bpm because of concerns about efficacy, risk of acceleration, and delay of definitive shock therapy. This prospective, multicenter study evaluated the efficacy of empirical ATP to terminate fast VT (FVT; Ͼ188 bpm). Methods and Results-Two hundred twenty coronary artery disease patients received ICDs for standard indications.Empirical, standardized therapy was programmed so that all FVT episodes (average cycle length [CL] 240 to 320 ms, 250 to 188 bpm) were treated with 2 ATP sequences (8-pulse burst pacing train at 88% of the FVT CL) before shock delivery. A total of 1100 episodes of spontaneous ventricular tachyarrhythmias occurred during a mean of 6.9Ϯ3.6 months of follow-up. Fifty-seven percent were classified as slow VT (CLՆ320 ms), 40% as FVT (240 msՅCLϽ320 ms), and 3% as ventricular fibrillation (CLϽ240 ms). A total of 446 FVT episodes, mean CLϭ301Ϯ24 ms, occurred in 52 patients (median 2 episodes per patient). ATP terminated 396 FVT episodes (89%), with an adjusted efficacy of 77% (95% CI 68% to 83%). VT acceleration caused by ATP occurred in 10 FVT episodes (4%). FVT arrhythmic syncope occurred on 9 occasions (2%) in 4 patients. Conclusions-FVT (CLϽ320 ms) is common in ICD patients. ATP can terminate 3 of 4 of these episodes with a low incidence of acceleration and syncope. ATP for FVT may safely reduce the morbidity of painful shocks.