Increased stroke risk in atrial fibrillation patients with heart failure: does ejection fraction matter?

S troke is a devastating complication of atrial fibrillation (AF), causing substantially greater neurological deficit than strokes in non-AF patients, as well as longer hospital admission, higher rates of death, and reduced ability to function independently. The risk of stroke in AF is not homogeneous and is closely associated with common patient characteristics, as summarized by the CHA 2 DS 2-VASc score, which incorporates heart failure, hypertension, age, diabetes mellitus, female sex, prior stroke or embolic events, and vas-cular disease. 1 In patients with AF, heart failure has been strongly associated with increased stroke/thromboembolism and mortality and independently adds to risk prediction of outcomes. 2 Congestive heart failure is represented by the C criterion in the CHA 2 DS 2-VASc score to represent the higher stroke risk associated with recent decompensated heart failure irrespective of ejection fraction (thus including heart failure with reduced ejection fraction [HFrEF] and heart failure with preserved ejection fraction [HFpEF]), as well as moderate-severe left ventricular systolic impairment on echocardiography. 1 This is in contrast to older risk scores, where heart failure only referred to recent decompensated heart failure, and there was some uncertainty whether HFrEF or HFpEF or asymptomatic systolic impairment should be included. 3 Of note, there is a reasonable evidence base linking a clinical diagnosis of heart failure with stroke and systemic embolus (relative risk of 1.6– 3.1 across 5 studies). 2 In the current issue of Stroke, Sandhu et al 4 add to a growing body of data examining whether adverse outcomes are similar in patients with HFpEF compared with those with HFrEF. As HFpEF is now the commonest form of heart failure, 5 unpick-ing the effect of heart failure on stroke outcomes in AF is vital for accurate risk stratification and appropriate use of antico-agulation for stroke prevention. 6 Using data from heart failure patients on antiplatelet agents enrolled in the ACTIVE A and W trials, Sandhu et al 4 identified no difference in the risk of stroke, transient ischemic attack, or systemic embolism between AF patients with HFpEF and HFrEF. This finding is similar to published data from other post hoc assessments of randomized trials 7–9 and observational cohort studies. None have identified a significant difference in incident stroke according to type of heart failure, although a trend toward more strokes in HFpEF was observed overall. In a large retrospective cohort study, McManus et al reported that preexisting AF was …