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.