Limitation:
The main limitations of this study are as following. Firstly, all the included studies are observational design and significant differences in clinical characteristics between CRT-D and CRT-P were observed. Even though we extracted adjusted HR to minimize the influence of those confounders and made results more reliable, the influence of unknown confounders still cannot be eliminated. Secondly, the majority of including studies are from European; therefore, the effect of additional ICD on all-cause mortality may not be generalizable to population from other areas. Thirdly, sample size varied greatly across the included studies, which means a different statistical power of included studies. However, sensitivity analysis of primary outcome suggested a stable result. Fourthly, limited by high heterogeneity and little data, this work cannot illustrate the benefits of CRT-D in long-term follow-up. Meanwhile, the impact of gender on benefits of CRT-D remains unclear. Finally, patient’s quality of life and re-hospitalization rate after implantation are vital clinical index to guide the device selection, but this meta-analysis did not focus on them.
Acknowledgments: Not applicable.
Funding: Not applicable.
Conflicts of interest/Competing interests: Not applicable
Availability of data and material: Not applicable
Code availability: STATA 14 (Stata Corp LP, College Station, Texas)