Investigation of left ventricular ejection fraction in a Swiss heart failure population: Insights into mortality and sex differences

Abstract

Aims: Understanding heart failure (HF) characteristics is essential to improve patient outcomes. Categorizing HF beyond left ventricular ejection fraction (LVEF) is challenging due to heterogeneous clinical presentation and aetiologies. Despite global studies on HF, the role of LVEF on mortality remains controversial. We explored the association of LVEF with mortality, considering sex differences and comorbidities in a cohort from the largest tertiary cardiovascular centre in Switzerland.

Methods: HF patients admitted to the University Hospital of Bern from January 2015 to December 2019 were evaluated. LVEF was used to classify patients into HF with preserved ejection fraction (HFpEF), HF with mid-range ejection fraction (HFmrEF) and HF with reduced preserved ejection fraction (HFrEF) categories. Cox proportional hazard models and time-stratified analyses adjusted for potential confounders were employed.

Results: A total of 5824 HF patients were included, and 2912 died over a median follow-up time of 3.39 years. Mortality rates across LVEF categories showed no significant differences, while overall, women showed significantly higher mortality; 30 day mortality was lower in the HFpEF category [hazard ratio (HR) 0.67, 95% confidence interval (CI): 0.52-0.88, P = 0.003], with persistent effects upon stratification in males (HR 0.59, 95% CI: 0.42-0.81, P < 0.001) and non-diabetics (HR 0.62, 95% CI: 0.44-0.87, P = 0.005). An isolated reduction in HFpEF mortality was observed in females after 1 year (HR 0.72, 95% CI: 0.53-0.98, P = 0.035).

Conclusions: The prognostic role of LVEF on all-cause mortality remains unclear, while differences in mortality rate distribution between women and men mirror established HF pathophysiological sex differences. Future HF studies should focus on HF aetiology and include measures beyond LVEF for comprehensive characterization.

Keywords: heart failure; sex differences.

Figure 1

Flowchart of study participants. HF, heart failure; LVEF, left ventricular ejection fraction.

Figure 2

General time‐stratified analysis (Model 2 adjusted for comorbidities). HFmrEF, HF with mid‐range ejection fraction; HFpEF, HF with preserved ejection fraction; HFrEF, HF with reduced ejection fraction.

Figure 3

Time‐stratified analysis (Model 2 adjusted for comorbidities, stratified by sex). HFmrEF, HF with mid‐range ejection fraction; HFpEF, HF with preserved ejection fraction; HFrEF, HF with reduced ejection fraction.

Figure 4

Time‐stratified analysis (Model 2 adjusted for comorbidities, stratified by T2DM status). HFmrEF, HF with mid‐range ejection fraction; HFpEF, HF with preserved ejection fraction; HFrEF, HF with reduced ejection fraction; T2DM, type 2 diabetes mellitus.

Figure A1

Kaplan–Meier curves. HFmrEF, HF with mid‐range ejection fraction; HFpEF, HF with preserved ejection fraction; HFrEF, HF with reduced ejection fraction.