Primary prevention implantable cardioverter defibrillator in patients with non-ischaemic cardiomyopathy: a meta-analysis of randomised controlled trials

Objectives The objective of this meta-analysis of randomised controlled trials (RCTs) is to evaluate the role of primary prevention implantable cardioverter defibrillator (ICD) in patients with non-ischaemic cardiomyopathy (NICM). Setting A meta-analysis of RCTs performed according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. Data sources The PubMed, MEDLINE, Embase and Cochrane Central Register of Controlled Trials databases were searched for relevant articles. Participants A total of 5 RCTs with 2573 patients with NICM were included. Intervention Primary prevention ICD, compared with medical therapy alone. Primary and secondary outcome measures All-cause mortality (primary outcome) and sudden cardiac death (SCD, secondary outcome). Data analysis Summary estimate HR were constructed using the random-effect DerSimonian and Laird's model. Multiple study-level subgroup analyses were performed, and interaction was tested using random-effect analysis. Results Compared with medical therapy alone, ICD placement was associated with lower risk of all-cause mortality (HR 0.79; 95% CI 0.64 to 0.93; p<0.001; I-2=0%) at a mean follow-up of 4.2 years. The risk of SCD was also lower with ICD placement (RR 0.47; 95% CI 0.30 to 0.73; p=0.001; I-2=0%) compared with control. On subgroup analyses, there was a suggestion of possible effect modification by age, in which benefit was observed in age group <60 years (HR 0.64; 95% CI 0.47 to 0.89), but not with age >= 60 years (HR 0.82; 95% CI 0.65 to 1.03) (P-interaction =0.058), but not with other study-level variables. Conclusions Compared with medical therapy alone, primary prevention ICD therapy in patients with NICM is associated with a significant reduction in all-cause mortality, especially in younger patients. Future dedicated studies are needed to investigate the role of primary prevention ICD in the elderly population.