Impact of prolonged implantable cardioverter-defibrillator arrhythmia detection times on outcomes: A meta-analysis

BACKGROUND Programming Long arrhythmia detection times can reduce the incidence of implantable cardioverter-defibrillator (ICD) shock therapy. However, potential concerns exist regarding the impact on mortality and incidence of syncope. OBJECTIVE The purpose of this study was to perform a meta-analysis to better gauge the impact of prolonged arrhythmia detection times on the rates of ICD shock therapy and other adverse outcomes. METHODS Electronic databases were systematically searched. We included only prospective studies that examined the impact of programming longer vs shorter ICD arrhythmia detection times on clinical outcomes. Studies that were retrospective, did not have a control group, used historical controls, or did not specifically state the programmed detection times were excluded. Summary estimates of the relative risk (RR) of death, syncope, and appropriate and inappropriate shocks were calculated using random effects models. RESULTS Four studies enrolling 4896 patients were identified. During a mean/median follow-up of 12 to 17 months, there were 305 deaths, 106 patients experienced syncope, 264 received an appropriate shock, and 253 an inappropriate shock. In the Long detection group there were significant reductions in mortality (RR 0.77, 95% confidence interval [CI] 0.62, 0.96), and inappropriate shocks (RR 0.50, 95% CI 0.39, 0.65), without significant increase in syncope (RR 1.23, 95% CI 0.84, 1.79). CONCLUSION Programming Long arrhythmia detection times is an important strategy for improving outcomes from ICD therapy. The use of Long detection times can significantly decrease the burden of inappropriate shock therapy and all-cause mortality in ICD recipients, without significant increase in syncope.