SURF (stroke with underlying risk of atrial fibrillation): Proposals for a definition

Diagnosis of occult atrial fibrillation (AF) in stroke patients remains challenging. Several scores predictive of occult AF in stroke patients have been proposed, all based on the positive predictive value of clinical, biological, and radiological parameters, but they failed to modify the management of AF detection after stroke. The aim of this study was to identify a group of Stroke patients with Underlying Risk of Atrial Fibrillation (SURF) excluding stroke patients with low risk of AF.

We enrolled consecutive AF-naive stroke patients without indication of long-term anticoagulation. AF was adjudicated after prolonged Holter ECG and 2 years of follow-up. The negative predictive value (NPV) was determined for each relevant parameter in the acute phase. Firstly, clinico-radiological parameters with NPV > 95% defined the initial exclusion criteria of SURF. Secondly, the ultimate exclusion criterion of SURF was defined by a composite criterion constructed using the beta-coefficient of independent predictive parameters of AF determined by logistic regression.

Among 773 AF-naïve patients without indication of anticoagulation, 111(14.4%) AFs were found. Initial SURF exclusion criteria, determined by NPV ≥ 95%, are: symptomatic atherosclerotic stenosis ≥50%, symptomatic arterial dissection or lacunar stroke. The SURF definition was completed by a composite exclusion criterion [Age*10+BNP< = 700] (NPV: 96.8%[92.6-98.9]). In the SURF group, 93/195(47.7%) AFs were diagnosed.

In the SURF group, nearly half of the stroke patients had AF. The criteria used to define such a group are easily obtained in all stroke units, in the acute phase. SURF is a new concept proposal, which aims to improve the effectiveness of AF diagnosis after stroke.