Prevalence and Incidence of Atrial Fibrillation in Ambulatory Patients with Heart Failure

Heart failure (HF) and atrial fibrillation (AF) commonly co-exist. We aimed to determine the prevalence and incidence of AF in ambulatory patients with HF. HF was defined by the presence of symptoms or signs supported by objective evidence of cardiac dysfunction: either a left ventricular ejection fraction (LVEF) ≤45% (HFrEF), or LVEF >45% and a raised plasma concentration of amino-terminal pro-B type natriuretic peptide (NT-proBNP>220ng/L; HFpEF). Of 3,570 patients with HF, 1,164 were in AF at baseline (33%), with a higher prevalence among patients with HFpEF compared to HFrEF (40% vs 26%, respectively, p<0.001). Compared to patients with HF in sinus rhythm (SR), those in AF were older, had more severe symptoms and higher NT-proBNP, worse renal function and were more likely to receive loop diuretics, despite having a higher LVEF. Of those in SR, 1,372 patients had HFrEF and 1,034 had HFpEF. The incidence of AF at one year (3.0%) was similar for each phenotype (p=0.73). Increasing age, male sex, history of paroxysmal AF and higher plasma concentrations of NT-proBNP were independent predictors of incident AF during a median follow-up of 1,574 (IQR: 749-2,821) days; the predictors were similar for each phenotype. In conclusion, the prevalence of AF is high, especially in patients with HFpEF, but its incidence is modest. This may be because their onset is near simultaneous with the development of AF precipitating the onset of HF.