• atrial fibrillation
• stroke
• pacemakers
• implanted cardiac defibrillators
• ECG/electrocardiogram

The prevalence of atrial fibrillation (AF) among adults over the age of 20 years is estimated to be 3% with 25% of middle-aged adults expected to develop AF during their lifetime.1 However, undiagnosed AF is common, especially in higher risk patient populations, including the elderly and patients with concomitant cardiovascular comorbidities. For example, patients who presented with a cryptogenic stroke and no history of AF were diagnosed with AF at rates of 8.9% at 6 months and 12.4% at 12 months poststroke, when an implantable cardiac monitor was used.2 A screening programme in Sweden checked intermittent electrocardiograms (ECGs) over a 2-week period in the general population of people aged 75 years and found that 3% had undiagnosed AF with 0.5% being diagnosed with the first ECG.3

Despite the available data on the rates of undiagnosed AF, the optimal screening strategy for AF remains debated and an active area of investigation. The European Guidelines for AF recommend ‘opportunistic screening’ for patients ≥65 years of age by checking a pulse for irregularity or ECG rhythm strip and at least 72 hours of monitoring in patients with ischaemic stroke or transient ischaemic attack.1 In the lack of any large outcome screening studies, the American College of Cardiology/American Heart Association/Heart Rhythm Society guidelines do not provide recommendations for screening, while an international collaboration of providers recommend: (1) screening all patients ≥65 years of age with a single time point, single lead ECG or pulse check for irregularity followed by an ECG; (2) patient activated ECG screening for a 2-week period in patients ≥75 years of age or in younger patients at a high risk for AF; and (3) long-term continuous monitoring in patients with an embolic stroke of undetermined source (ESUS).4

Beyond the question of whom to screen, physicians need to decide which devices …