Time-trend treatment effect of Cardiac Resynchronization Therapy with or without Defibrillator on Mortality -A Systematic Review And Meta-Analysis.

CRT-D was able to reduce all-cause mortality by almost 20% over CRT-P (aHR:0.85; 95%CI:0.76-0.94; p<0.01) even in propensity-matched studies (HR:0.83; 95%CI:0.80-0.87; p<0.001), but not in those with non-ischemic etiology (HR 0.95, 95%CI:0.79-1.15; p=0.19) or over 75 years (HR 1.08, 95%CI 0.96-1.21; p=0.17). When treatment effect on mortality was investigated by the median year of inclusion, there was a difference between studies released before 2015 and those thereafter. Time-trend effects could be also observed in patients' characteristics: CRT-P candidates were getting older and the prevalence of ischemic etiology were increasing over time.Conclusion: The results of this systematic review of observational studies, mostly retrospective with meta-analysis, suggest that patients with CRT-D had a lower risk of mortality compared to CRT-P. However, subgroups could be identified, where CRT-D was not superior such as non-ischemic and older patients. An improved treatment effect of CRT-D on mortality could be observed between the early and late studies partly related to the changed characteristics of CRT candidates.