Background: Atrial fibrillation (AF) is a common heart rhythm disorder with various clinical presentations, including asymptomatic AF, known as silent AF. High-risk patients not treated with anticoagulants are at increased risk of stroke. Therefore, systematic screening has been evaluated to reduce death and cardiovascular complications. Concentrating screening efforts on high-risk populations may optimize the effectiveness of future screening strategies. The aim of our study was to determine the prevalence of silent AF in a high-risk population 65 years or older with diabetes mellitus type 2 (DM2) or congestive heart failure (CHF).

Methods: A multicentre, observational, prospective cohort study of 645 patients with DM2 or CHF screened for AF in primary care and outpatient clinics in Denmark, Sweden, and Austria from 2016 to 2020. Patients were examined by intermittent electrocardiogram (ECG) recordings using a handheld ECG device 4 times daily for 2 weeks. AF was diagnosed with at least 1 recording (30 seconds) of AF. Patients with fewer than 40 recordings were excluded from the analyses.

Results: Overall 3.3 %, 3.0%, and 3.9%, respectively, of the patients with DM2 and CHF, and 5.5% of patients older than 74 years were diagnosed with previously undetected AF.

Conclusions: Intermittent handheld ECG screening revealed AF in 1 in every 30 patients in a high-risk population, with an increased observed risk in elderly patients. Clinical Registration Number: H-16015331.