The prognostic value of atrial fibrillation (AF) in heart failure with preserved ejection fraction (HFPEF) remains controversial. The objective of the KaRen (Karolinska-Rennes) sub-study was to explore this question.

KaRen was a prospective, multicenter, international, observational study intended to characterize HFPEF; 538 patients presenting acute decompensated cardiac failure with a left ventricular ejection fraction>45% were included. A physical exam as well as an EKG and an echocardiogram were scheduled 4-8 week following the index hospitalization, and the patients were evaluated at 6-month intervals.

We compared clinical and echocardiographic characteristics of patients in sinus rhythm vs. patients with documented AF upon their 4-8-week visit. The primary study endpoint was death from any cause or first hospitalization for decompensated heart failure (HF).

A total of 413 patients (244 patients in sinus rhythm and 134 in AF; 32% of overall population) were analyzed, with a mean follow-up period of 28 months. The patients were primarily elderly individuals (76.2 years), with a slight female predominance and a high prevalence of comorbidities. The baseline echo-cardiographic characteristics and the natriuretic peptide levels were indicative of a more severe heart condition among the patients with AF. However, the patients with AF exhibited a similar survival-free interval compared with the patients in sinus rhythm (p=0.89). Similar survival was observed according to patients’ heart rhythm on enrolment (decompensated HF) or according to patients’ cardiac history. Heart rate (stratified in tertiles), neurohormonal blockade or anticoagulant treatments at the 4-8-week visit were not independent predictors of outcome.

In this HFPEF population with a high prevalence of non-cardiovascular comorbidities, the presence of AF was not associated with a poorer prognosis despite impaired clinical and echocardiographic features.