The Heart Sentinel™ app for detection and automatic alerting in cardiac arrest during outdoor sports: Field tests and ventricular fibrillation simulation results

Abstract Introduction The Heart Sentinel™ app (HS-app) is conceived to detect cardiac arrest during outdoor sports, automatically alerting contacts via SMS with GPS position data. It automatically starts the chain of survival in case no bystander has witnessed the event, using commercially-available chest strap heart monitor and a smartphone. The heart rate analysis arm of the algorithm is extremely sensitive, with specificity being addressed by motion analysis through smartphone sensors, since only unexpected prolonged absence of motion would confirm true cardiac arrest and start an alert code. We assessed the accuracy of such HS-app with simulated exercise-associated ventricular fibrillation (VF), and possible false positives in real-world athletes. Methods The occurrence of false positive alerts was tested in the outdoor field, through athletes regularly running and cycling, and with ECG simulators. The occurrence of false negatives for VF detection was assessed with 3 different ECG simulators, using VF simulation protocols. Results The false positive initiation of an alert countdown was recorded twice during 829 h of outdoor sports. Both athletes were able to stop such false positive 15-second countdown before the alert SMS was dispatched. No false positive SMS was dispatched. False negatives were not recorded under any simulation protocol. Conclusion A simple smartphone app, using commercially-available heart rate monitors, is promising to detect cardiac arrest caused by VF during sports, triggering automatic dispatch of emergency SMS with GPS position. During outdoor exercise, HS-app would be helpful for cases of exercise-associated cardiac arrest.