Discussion
In this meta-analysis, firstly, we have demonstrated that additional ICD therapy shows a mortality benefit in patients undergoing CRT even though using HR adjusted by variables. For patients undergoing CRT-D for primary prevention or from non-European countries, there is no mortality benefit of CRT-D compared with CRT-P. Then, in consideration of the significant difference in clinical characteristic between CRT-P and CRT-D recipients, propensity score matching (PSM) was used in several studies to controls the variables more strictly, which eliminated this advantage of CRT-D in all-cause mortality. Finally, in the subpopulation, CRT-D reduced all-cause mortality in ischemic cardiomyopathy patients compared with CRT-P, but this effect is insignificant in non-ischemic cardiomyopathy or older age patients.