Mid-range left ventricular ejection fraction: Clinical profile and cause of death in ambulatory patients with chronic heart failure.

BACKGROUND: The intermediate group of patients with heart failure (HF) and mid-range left ventricular ejection fraction (HFmrEF) may constitute a specific phenotype, but a direct evidence is lacking. This study aimed to know whether this HF category is accompanied by a particular clinical phenotype and prognosis.

METHODS AND RESULTS: This study includes 3446 ambulatory patients with chronic HF from two national registries. According to EF at enrollment, patients were classified as reduced (HFrEF, <40%), mid-range (HFmrEF, 40-49%) or preserved (HFpEF, ≥50%). Patients were followed-up for a median of 41months and the specific cause of death was prospectively registered. Patients with HFmrEF represented 13% of population and they exhibited a phenotype closer to HFrEF, except for a higher rate of coronary revascularization and diabetes, and a less advanced HF syndrome. The observed all-cause mortality was higher among HFrEF (33.0%), and similar between HFmrEF (27.8%) and HFpEF (28.0%) (p=0.012); however, the contribution of each cause of death differed significantly between categories (p<0.001). After propensity score matching, the risk of cardiovascular death, HF death or sudden cardiac death did not differ between HFmrEF and HFrEF in paired samples; however, patients with HFmrEF were at higher risk of cardiovascular death (sHR 1.71, 95% CI 1.13-2.57, p=0.011) and sudden cardiac death (sHR 2.73, 95% CI 1.07-6.98, p=0.036) than patients with HFpEF.

CONCLUSIONS: Patients in the intermediate category of HFmrEF conform a phenotype closer to the clinical profile of HFrEF, and associated to higher risk of sudden cardiac death and cardiovascular death than patients with HFpEF.