Stroke is the leading cause of death and disability. In a large proportion of cases, atrial fibrillation is undetected, because it is often asymptomatic and/or paroxysmal. A first diagnosis of atrial fibrillation may occur at the time of stroke (e.g. about 45% of patients with acute stroke and atrial fibrillation were formerly undiagnosed). Against this backdrop, oral anticoagulant therapy is extremely effective at reducing the risk of ischemic stroke in atrial fibrillation, associated with a two-thirds risk reduction (closer to 80% risk reduction in those adherent with treatment). Therefore, a major care gap in stroke prevention is the prevalence of undetected atrial fibrillation in the community. A clinical trial has shown that opportunistic pulse screening (with ECG confirmation) in all patients over 65 years detects new atrial fibrillation in about 1% of people. While such an approach is suited to detecting continuous atrial fibrillation, it is unsuited for detecting paroxysmal atrial fibrillation, which requires continuous monitoring. Moreover, such an unselected approach does not take into account whether patients are suited to oral anticoagulants. The traditional Holter monitor is unsuited for screening, given its limited duration (24-48 hours), and resource challenges in interpretation. The emergence of event loop recorders (ELRs) presents an opportunity for wider application, as they use algorithm-based detection, but their suitability for screening large population is uncertain. In this clinical trial, we evaluate the effectiveness of a novel approach to detecting covert atrial fibrillation in General Practice, using a two-step approach; a) identify through computer-database search patients at high-risk of atrial fibrillation (using CHA2DS2-VASc score) and deemed suitable by their GP for oral anticoagulants, and b) randomize to; immediate or delayed (after 3 months) externally worn ELR for 2 weeks to detect paroxysmal atrial fibrillation compared to standard care (n=1,052 from 11 GP practices). In a SWAT, we evaluate the accuracy of regular pulse self-screening for atrial fibrillation against ELR, to explore its potential utility in identifying patients at increased risk of atrial fibrillation. Our clinical trial targets a major key care-gap in stroke prevention, and may transform our approach to detecting covert atrial fibrillation in the community.
