WATCH AFib: Smartwatches for detection of atrial fibrillation in secondary prevention of cryptogenic stroke – protocol for a prospective, intraindividual-controlled, multicentre clinical study

Horst Penkert^1*Johanna Härtl¹Alexander Hapfelmeier²Silvia Egert-Schwender³Edith Heimsch³Sabine Friedenberg³Alexander Mueller⁴Franziska Hahn⁴Eimo Martens⁴Silke Wunderlich^1*

• ¹Technical University of Munich, School of Medicine and Health, Department of Neurology, Munich, Germany
• ²Technical University of Munich, School of Medicine and Health, Institute of AI and Informatics in Medicine, Munich, Germany
• ³Technical University of Munich, School of Medicine and Health, Muenchner Studienzentrum (MSZ), Munich, Germany
• ⁴4. Technical University of Munich, School of Medicine and Health, Department of Internal Medicine I, Cardiology, Munich, Germany

Rationale: Detection of atrial fibrillation (AFib) and subsequent anticoagulation therapy reduce the risk of recurrent stroke, while prolonged rhythm monitoring significantly increases AFib detection. Thus, prolonged smartwatch-based ECG monitoring after cryptogenic ischemic stroke or transient ischemic attack (TIA) could lead to a reduction of recurrent stroke by prompting adequate anticoagulation therapy. Aim: WATCH AFib investigates the accuracy of smartwatches for AFib detection in patients with cryptogenic TIA or ischemic stroke compared to an implantable event recorder. Sample size: 40 cases of AFib are required to estimate the sensitivity for AFib detection per patient with a precision of about 10%. As AFib is observed in 9 – 16% of cryptogenic strokes, we intend to enroll 400 patients. Methods: WATCH AFib is a prospective, intraindividual-controlled, multicentre clinical study in patients with cryptogenic ischemic stroke or TIA. ECG-data from smartwatches and event recorders is continuously monitored by two independent cardiologists for a follow-up period of six months. If AFib is detected, therapeutic options are discussed at the including centre. Primary Outcome: To compare smartwatch-and event recorder-based sensitivity and specificity of AFib detection per patient after six months. Discussion: Prolonged AFib screening after stroke is currently suboptimal. Smartwatches might be a non-invasive, cost-effective, widely available alternative for prolonged rhythm monitoring. Usability in severely affected patients and patients with persisting neurological deficits might be limited. Trial registration: The study is registered on clinicaltrials.gov. Registration number: 20230726.