Background Atrial fibrillation (AF) is a significant risk factor for ischaemic stroke, however is often asymptomatic and therefore unrecognised. Previous work suggested up to two patients per day may have a new diagnosis of AF identified by Emergency Medical Services (EMS) in North East England. This study aimed to quantify the regional population not transported to hospital following EMS review with apparent new AF who were potentially eligible for oral anticoagulation (OAC) to reduce their risk of stroke.

Methods A retrospective audit of patients aged over 18 years assessed by EMS but not transported to hospital, where an irregular pulse was identified, between 1^st February and 30^th April 2022. Cardiac arrest patients were excluded. Medical history including stroke risk score (CHA₂DS₂-Vasc), past history of AF, and prescription of OAC were extracted from the EMS record.

Results Over the study period 7,055 people were attended by EMS, had a pulse rhythm recorded and were not transported to hospital. This included 840/7055 (11.9%) with an irregular pulse. Of these 303/7055 (4.3%) had an ECG interpretation recorded, which included AF in 245/7055 (3.5%). In 18/7055 (0.3%) patients this appeared to be a new diagnosis because they were not already prescribed OAC. Of these, 17/18 (94.4%) had a CHA₂DS₂-Vasc score of two or more, therefore eligible for OAC consideration.

Conclusion Apparent new AF can be identified in the non-conveyance population. These results suggest that ambulance services could provide a new screening opportunity for stroke prevention if an acceptable anticoagulation treatment pathway can be developed and implemented.

Further research is required because these data were collected retrospectively from ambulance records, with variability in the clinical information documented. Also, as many ambulance records typically do not include documentation of a pulse rhythm, there could be further unidentified cases.