Smart Wristband Technology Detects Cardiac Arrest and Alerts Responders

Out-of-hospital cardiac arrest is a sudden loss of heart function that often occurs without witnesses and demands immediate response. Delayed recognition and activation of emergency services reduce survival and neurological recovery. Continuous, unobtrusive monitoring could help identify arrest earlier and mobilize help faster. To help address this challenge, researchers have now evaluated a wearable wristband that aims to automatically detect shockable cardiac arrest rhythms and trigger alerts.

In the DETECT‑1b study conducted at Radboud University Medical Center (Nijmegen, Netherlands), investigators analyzed data from 49 adults undergoing procedures during which life‑threatening arrhythmias were briefly induced for clinical testing. Ventricular fibrillation and pulseless ventricular tachycardia were provoked under controlled conditions. The evaluation assessed whether a medically certified wrist‑worn device could recognize when the heart stopped effectively pumping blood.

The wristband uses a photoplethysmography (PPG) algorithm that continuously measures changes in blood flow at the wrist. By tracking the loss of pulsatile flow, the system is designed to infer cardiac arrest and initiate an automated alert to responders. This approach allows continuous and unobtrusive monitoring consistent with daily wear.

Across 59 induced shockable cardiac arrest events, the algorithm detected arrest in 92% of cases, including 100% of ventricular fibrillation and 90% of pulseless ventricular tachycardia. During 125 hours of recording, nine events were classified as false positives. In a per‑patient analysis that considered only the first event per person, detection accuracy was 92%.

The findings were published in Circulation: Arrhythmia and Electrophysiology. Investigators described the work as an external validation using patient data and noted that many commercial wearables use similar light‑based sensors but are not designed to detect arrest. The study was performed in a controlled clinical setting, and the authors stated that real‑world effectiveness and reliability require further evaluation.

The effort is part of the broader DETECT project, a collaboration among several hospitals and a company in the Netherlands to develop a smart wristband capable of automated cardiac arrest detection and alerting emergency services. Future development aims to connect alerts to emergency dispatch centers and volunteer responder networks.

“Our findings are important because many out-of-hospital cardiac arrests are unwitnessed. A smart technology wristband capable of automatically detecting cardiac arrest and triggering an alert could function as a digital witness,” said Judith Bonnes, M.D., Ph.D., cardiologist at Radboud University Medical Center in Nijmegen, Netherlands. "With the device automatically notifying emergency services or nearby trained responders, help could arrive sooner, which may significantly improve survival chances."

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Radboud University Medical Center