Etiologic impact on difference on clinical outcomes of patients with heart failure after cardiac resynchronization therapy A systematic review and meta-analysis

Objective: To compare long-term clinical outcomes between patients with heart failure due to non-ischemic cardiomyopathy (NICM) and those due to ischemic cardiomyopathy (ICM) after cardiac resynchronization therapy (CRT). Methods and Results: EMbase, PubMed, and Cochrane Library were searched for published studies up to December 2017. Twenty-one observational studies with 12,331 patients were enrolled in the present meta-analysis. The results demonstrated that the all-cause mortality in NICM patients was significantly lower than that in ICM patients (RR 1.37, 95% CI 1.16-1.61). In terms of echocardiographic parameters, NICM patients exhibited statistically significant improvement in left ventricular ejection fraction (LVEF) (MD 2.70, 95% CI -4.13 to -1.28), and a significant decrement in left ventricular end-systolic volume (LVESV) (MD 10.41,95% CI 2.10-18.73) and left ventricular end diastolic diameter (LVEDD) (MD 7.63, 95% CI 2.59-12.68) as compared with ICM patients. No significant difference was observed in the improvement of New York Heart Association Functional Classification (MD 0.05, 95% CI - 0.05 to 0.15), pulmonary arterial systolic pressure (PASP) (MD -0.61, 95% CI -4.36 to 3.14), and severity of mitral regurgitation (MD 0.00, 95% CI -0.08 to 0.07) between the 2 groups. Conclusions: Our meta-analysis illustrated that patients with HF due to NICM tended to have better clinical outcomes and LV reverse remodeling as compared with those due to ICM. This finding may help clinicians select patients who respond favorably to CRT, though further research is required to clarify the potential confounding factors and underlying mechanisms for this phenomenon.