Implantable cardioverter defibrillators (ICDs) reduce the risk of sudden cardiac death in patients with impaired left ventricular ejection fraction (LVEF). However, there are limited data on the long-term benefit of ICD therapy in patients whose LVEF subsequently improves. We conducted a meta-analysis to evaluate the effect of LVEF improvement on ICD therapy during follow-up. Incidence rate ratios (IRRs) with 95% confidence intervals (CIs) were calculated using random-effects modeling. Sixteen studies with 3,959 patients were included in our analysis. Study arms were defined by LVEF improvement at follow-up (improved LVEF [>35%]: 1,622; low LVEF [≤35%] 2,337). Mean age (64.8 vs 64.9 years, p = 0.97) was similar, whereas men were overrepresented in the persistent low LVEF group (79% vs 72%, p <0.001). Appropriate ICD therapy rate was 9.7% (improved LVEF) versus 21.8% (low LVEF) over a median follow-up period of 2.9 years. In the meta-analysis, improved LVEF group had significantly lower (3.3% vs 7.2% per year IRR 0.52; CI 0.38 to 0.70; p <0.001) appropriate ICD therapies which was uniformly seen across all subgroups (ICD-only studies: IRR 0.59; p = 0.004) (cardiac resynchronization therapy-defibrillator–only studies: IRR 0.31; p = 0.002) (super-responder studies [mean LVEF > 45%]: IRR 0.53; p = 0.002). Inappropriate ICD therapy rates were, however, similar in both groups (3.01% vs 2.56% per year IRR 0.76; CI 0.43 to 1.36; p = 0.35). All-cause mortality rates in our meta-analysis favored (3.63% vs 8.23% per year IRR 0.49; CI 0.35 to 0.69; p <0.001) the improved LVEF group. In conclusion, our meta-analysis demonstrates that an improvement in LVEF is associated with a significantly reduced risk of ventricular arrhythmia and mortality. However, inappropriate ICD therapy rates remain similar.
All Science Journal Classification (ASJC) codes
- Cardiology and Cardiovascular Medicine