Objective: This study aims to investigate the prevalence and prognostic impact of atrial fibrillation (AF) in patients hospitalized due to heart failure with mildly reduced ejection fraction (HFmrEF). 

Background: Limited data regarding the prevalence and prognostic impact of AF in patients with HFmrEF is available.

Methods: A large retrospective registry was used including all consecutive hospitalized patients with HFmrEF (i.e., left ventricular ejection fraction (LVEF) 41 – 49%) from 2016 to 2022 according to current European guidelines. The prognostic impact of AF was compared non-AF patients. The primary endpoint was the first heart-failure related re-hospitalization at 36 months. Secondary endpoints comprised in-hospital mortality and cardiovascular re-hospitalization at 36 months. Kaplan-Meier, uni- and multivariable Cox regression analyses were applied for statistics.

Results: 803 consecutive HFmrEF patients were included. 40% suffered from AF (paroxysmal 56%, persistent 14%, permanent AF 29%, firstly diagnosed 24%). Comparable levels of aminoterminal pro-brain natriuretic peptide (NT-pro BNP) levels were found (median 8455 vs. 6434ng/l, p = 0.219). HFmrEF patients with AF were associated with an increased risk of heart-failure related re-hospitalization compared to non-AF patients (15% vs. 5%; log-rank p=0.001; HR=3.352; 95% CI 2.039 – 5.510; p=0.001). Even after multivariable adjustment, the risk of heart failure related re-hospitalization was still significantly higher in AF patients (HR=2.595; 95% CI 1.531 – 4.400; p=0.001). In contrast, AF subtypes did not reveal any impact on heart-failure related re-hospitalization (log-rank p=0.347). Finally, AF patients revealed higher rates of in-hospital mortality (7% vs. 1%; p=0.001) as well as cardiovascular re-hospitalization (23% vs 16%; p=0.007; HR=1.548; 95% CI 1.125 - 2.129; p=0.007) even after multivariable adjustment (HR 1.484; 95 CI 1.050 – 2.096; p=0.025).
Conclusions: AF impairs prognosis in patients with HFmrEF.