Results:

Of 22,219 adults with ≥2 echocardiograms separated ≥6 months apart, the study authors analyzed 10,641 patients who had a physician-assigned diagnosis of HF, and who had their LVEF objectively measured on both echocardiograms. Of this final cohort of 10,641 patients, 3,124 had HFrEF at baseline: While mean LVEF declined from 30.2% on initial echocardiogram to 28.6% on the second echocardiogram in those patients with persistent HFrEF (defined by <10% improvement in LVEF), it improved from 26.1% to 46.4% in 37.6% of the patients (n = 1,174) with HFrecEF (defined by LVEF absolute improvement ≥10%); 52.4% exhibited LVEF recovery ≥5%. Using multivariate analysis, factors that were associated with EF improvements ≥10% included female gender (adjusted odds ratio [aOR], 1.66; 95% confidence interval [CI], 1.40–1.96), younger age (aOR per decade 1.16; 95% CI, 1.09–1.23), atrial fibrillation (aOR, 2.00; 95% CI, 1.68–2.38), cancer (aOR, 1.52; 95% CI, 1.03–2.26), hypertension (aOR, 1.38; 95% CI, 1.18–1.62), lower baseline LVEF (aOR per 1% decrease, 1.07; 95% CI, 1.06–1.08), and using hydralazine (aOR, 1.69; 95% CI, 1.19–2.40). HFrecEF patients demonstrated lower rates per 1,000 patient-years of mortality (106 vs. 164, adjusted hazard ratio [aHR], 0.70; 95% CI, 0.62–0.79), all-cause hospitalizations (300 vs. 428, aHR, 0.87; 95% CI, 0.79–0.95), all-cause ER visits (569 vs. 799, aHR, 0.88; 95% CI, 0.81–0.95), and cardiac transplantation or LV assist device (LVAD) implantation (2 vs. 10, aHR, 0.21; 95% CI, 0.10–0.45) compared to patients with persistent HFrEF. Females with HFrEF exhibited lower mortality risk (aHR, 0.94; 95% CI, 0.88–0.99) than males after adjusting for age, time between echocardiograms, clinical comorbidities, medications, and whether their LVEF improved or not during follow-up. Also, females were significantly less likely to receive a LVAD or cardiac transplant (aHR, 0.46; 95% CI, 0.24–0.88), but there were no gender-based differences in rates of hospitalizations or ER visits.