IntroductionAtrial fibrillation (AF) is a major risk factor for stroke. There is a fivefold increase in stroke risk in the presence of AF. The irregular beating of the heart enables blood stasis which allows clots to form. These can migrate to the brain causing a stroke. AF is common and its incidence increases with age. AF is often asymptomatic and early detection enables effective preventive treatment reducing stroke risk by up to two-thirds.Stroke contributes significantly to morbidity and mortality globally. In Ireland, it is the leading cause of acquired disability and second leading cause of death. The cost associated with stroke is significant. Stroke risk increases with age and is a public health priority.Internationally, there is consensus among experts that AF screening is valuable. In Ireland, the National Cardiovascular Policy recommended establishing a screening programme. However, there are many ways to screen for AF including pulse palpation, mobile ECG devices, 12-lead ECG and personal health monitoring devices.This study aims to investigate the acceptability, feasibility and impact of AF screening in primary care using a handheld mobile ECG device.Methods and analysisGeneral practitioners (GPs) and practice nurses in the South of Ireland will opportunistically screen patients aged ≥65 years for AF at routine consultation using a handheld one-lead ECG device, KardiaMobile. This study will screen up to 4000 patients. Blood pressure and smoking status will be checked concurrently. A mixed-method evaluation will be undertaken including a partial economic evaluation. Anonymised data will be collected from participating practices and qualitative interviews will be conducted with GP, nurse and patient participants.Ethics and disseminationEthical approval has been granted by the Clinical Research Ethics Committee in University College Cork. Dissemination will involve publication in peer-reviewed journals and presentation at national and international conferences.