Abstract 4137672: Prevalence, Clinical Characteristics, and Outcomes in Heart Failure with Improved Ejection Fraction by Sex

Background: Heart failure with improved ejection fraction (HFimpEF) is a growing clinical entity. While males are more likely to present with HFrEF, there remains little understanding of how sex relates to the epidemiology, predictors, and progression of HFimpEF. Research Question: What are the differences in epidemiology, clinical characteristics, medical management, and outcomes in patients (pts) with HFimpEF based on sex. Methods: We identified adults age ≥18 years with incident HFrEF (EF ≤40%) between January 2013 and December 2018 within Kaiser Permanente Northern California, an integrated health system serving >4.5 million members. HFimpEF was defined as subsequent EF measurement >40% within the following 12 months. Sex was based on self-report. Among pts with HFimpEF, we examined guideline-directed medical therapy (GDMT) use at time of incident HFimpEF, and at 6- and 12-months post-HFimpEF, stratified by sex. The incidence of worsening HF (WHF) events and all-cause death was assessed in a landmark analysis at 12 months post-HFrEF. We compared event rates between patients with HFimpEF and persistent HFrEF using Cox proportional hazards models adjusted for baseline age and EF. Results: Among 12,639 patients with incident HFrEF (female: 36%), 33% experienced HFimpEF. Females were more likely to experience HFimpEF in the 12 months following HFrEF than males (34% vs. 32%, p<0.01). Among pts with HFimpEF, treatment with GDMT was similar among males and females and declined after incident HFimpEF in both sexes (Figure, Panel A). Females had similar rates of WHF or all-cause death compared to males (adjusted [a]HR: 1.10, 95% CI: 0.96, 1.26, P=0.17). Compared with those with persistent HFrEF, pts with HFimpEF had lower rates of WHF or all-cause death, a finding which was consistent by sex (male: aHR: 0.55, 95% CI: 0.50 to 0.61, female: aHR: 0.54, 95% CI: 0.48 to 0.62; Pinteraction by sex=0.78; Figure, Panel B). Conclusions: HFimpEF is more common among females compared to males, but prognosis is similar. Despite similar medical therapy, GDMT discontinuation after EF improvement is prevalent. Improvement in EF is similarly associated with improved outcomes across sex. Further data are needed to elucidate the differential etiologies of HF by sex.