Safety and efficacy of high-rate cutoff and long detection interval ICD programming in secondary prevention patients.

Several trials demonstrated that a long detection interval and a high-rate cutoff reduced implantable cardioverter-defibrillator (ICD) therapy in primary prevention patients. However, only a few data are available for secondary prevention (SP) patients. The aim of this study was to evaluate whether these ICD programming would be effective in reducing ICD therapies in SP patients. We enrolled 65 SP patients under ICD or cardiac resynchronization therapy with the defibrillator programmed with the same setting (conventional setting). During follow-up, we changed detection rates in each zone; cycle length (CL) ≤400 to ≤370 ms for ventricular tachycardia (VT) zone, CL ≤350 to ≤320 ms for fast VT zone, CL ≤300 to ≤270 ms for ventricular fibrillation (VF) zone, and number of intervals to detect ventricular tachyarrhythmia in VF zone: 12-24. We retrospectively compared the incidences of ICD therapies, syncope, and hospitalization due to slow VT under the detection rate between both settings. Median follow-up periods were 5.0 (interquartile range 2.5-7.8) and 2.5 years (interquartile range 2.3-2.7) in conventional and strategic settings, respectively. The incidence of appropriate ATP and shock significantly decreased in strategic setting (conventional and strategic settings: 21.2 and 4.8 ATPs per year, respectively, OR 0.18, 95 % CI 0.06-0.54, p = 0.002, 26.1 and 7.8 shocks per year, respectively, OR 0.29, 95 % CI 0.09-0.88, p = 0.03). The incidence of overall inappropriate therapy significantly decreased (conventional and strategic settings: 17.6 and 2.8 therapies per year, respectively, OR 0.14, 95 % CI 0.05-0.44, p = 0.01). The incidence of syncope and slow VT was not significantly different between both settings. In conclusion, ICD programming-combined long detection interval with high-rate cutoff was effective in reducing appropriate shock and inappropriate therapy without increasing the incidence of syncope and slow VT in SP patients.

Characterization and predictors of first and subsequent inappropriate ICD therapy by heart rate ranges: Result of the MADIT-RIT efficacy analysis.

BACKGROUND: Data on inappropriate implantable cardioverter-defibrillator (ICD) therapy and effects of programming by heart rate are lacking. OBJECTIVE: We aimed to characterize inappropriate ICD therapy and assess the effects of novel programming by heart rate. METHODS: Incidence and causes of inappropriate therapy by heart rate range (below or above 200 bpm) were assessed. Predictors of inappropriate therapy and effects of programming by heart rate were evaluated with multivariate Cox regression models. Crossovers were excluded. RESULTS: Inappropriate therapy occurred in 9.2% of the total patient population, with 19% of patients randomized to study arm A, 3.6% in arm B, and 4.7% in arm C. Inappropriate therapies <200 bpm were attributable to supraventricular tachycardia (SVT)/sinus tachycardia (78%) or atrial fibrillation/flutter (20%). Inappropriate therapy ≥200 bpm occurred because of SVT (47%), atrial fibrillation/flutter (41%), or electromagnetic interference (13%). Conventional ICD programming was associated with more inappropriate therapy <200 bpm than high-rate or delayed therapy, as were younger age, history of atrial arrhythmia, advanced New York Heart Association functional class, ICD versus cardiac resynchronization therapy with defibrillator, and absence of diabetes. High-rate and long-delay therapy significantly reduced the risk of inappropriate therapy in the <200 bpm range. Long delay was associated with further reduction of fast (≥200 bpm) inappropriate therapy (P = .032) and a reduction in subsequent inappropriate episodes (P = .006). CONCLUSION: In MADIT-RIT, inappropriate ICD therapy is most frequent at rates below 200 bpm and can be predicted, and effectively prevented, with high-rate cutoff programming. Long-delay therapy effectively reduces fast inappropriate therapy ≥200 bpm and subsequent events. [ CLINICAL TRIAL REGISTRATION: http://clinicaltrials.gov/ct2/show/NCT00947310].