Heart failure patients with improved ejection fraction: insights from the MECKI Score database

Aims: Improvement of left ventricular ejection fraction is a major goal of heart failure (HF) treatment. However, data on clinical characteristics, exercise performance and prognosis in HF patients who improved ejection fraction (HFimpEF) are scarce. The study aimed to determine whether HFimpEF patients have a distinct clinical phenotype, biology and prognosis than HF patients with persistently reduced ejection fraction (pHFrEF). Methods and results: 7948 patients enrolled in the Metabolic Exercise Cardiac Kidney Indexes (MECKI) score database were evaluated (median follow-up of 1490 days). We analyzed clinical, laboratory, ECG, echocardiographic, exercise, and survival data from HFimpEF (n = 1504) and pHFrEF (n = 6017) patients. The primary endpoint of the study was the composite of cardiovascular death, left ventricular assist device implantation, and urgent heart transplantation. HFimpEF patients had lower HF severity: LVEF 44.0[41.0-47.0] vs. 29.7[24.1-34.5]%, BNP 122[65-296] vs. 373[152-888] pg/mL, hemoglobin 13.5[12.2-14.6] vs. 13.7[12.5-14.7] g/dL, renal function by MDRD 72.0[56.7-89.3] vs. 70.4[54.5-85.3] mL/min, peakVO2 62.2[50.7-74.1] vs. 52.6[41.8-64.3]%pred, VE/VCO2 slope 30.0[26.9-34.4] vs. 32.1[28.0-38.0] in HFimpEF and pHFrEF, respectively (p < 0.001 for all). Cardiovascular mortality rates were 26.6 and 46.9 per 1000 person-years for HFimpEF and pHFrEF, respectively (p < 0.001). Kaplan-Meier analysis showed that HFimpEF had better a long-term prognosis compared with pHFrEF patients. After adjustment for variables differentiating HFimpEF from pHFrEF, except echocardiographic parameters, the Kaplan-Meier curves showed the same prognosis. Conclusions: HFimpEF represents a peculiar group of HF patients whose clinical, laboratory, ECG, echocardiographic, and exercise characteristics parallel the recovery of systolic function. Nonetheless, these patients remain at risk for adverse outcome.