History of atrial fibrillation as a risk factor in patients with heart failure and preserved ejection fraction.

BACKGROUND Atrial fibrillation (AFib) is common in heart failure (HF) with preserved ejection fraction (HFpEF). Current AFib stroke risk prediction models include the presence of HF but do not specifically include HFpEF as a risk factor. Whether a history of AFib should be used to identify patients with HFpEF who are at risk has not been established. METHODS AND RESULTS Baseline characteristics and outcomes of patients with HFpEF in the Irbesartan in Heart Failure with Preserved Ejection Fraction Trial were analyzed in relation to AFib. At baseline, 1209 (29.3%) had a history of AFib. Of these 557 (13.5%) had history of AFib alone, whereas 670 (16.2%) had both a history and AFib on ECG; 2901 (70.3%) had neither. There were no significant differences in the risk of stroke between the 2 groups with a history of AFib who did or did not have AFib present on baseline ECG. During a median follow-up of 53 months, a fatal or nonfatal stroke occurred in 6.5% (79/1209) patients with history of AFib compared with 3.9% (114/2901) with no AFib. Having a history of AFib was independently associated with higher risk of stroke (hazard ratio, 2.2; 95% confidence interval, 1.6-3.2; P<0.0001) compared with those with no history of AFib. CONCLUSIONS In patients with HFpEF, a history of AFib was common and independently associated with increased risk of stroke, regardless of whether AFib was present on ECG. Patients with HFpEF and a history of AFib should be considered at risk. Further studies are needed to determine whether this risk can be safely reduced. CLINICAL TRIAL REGISTRATION URL http://www.clinicaltrials.gov. Unique identifier: NCT000095238.