Performance evaluation of smartwatches: Can they match clinical standards for ECG analysis?

Smartwatches have gained popularity in health monitoring. While initially focused on general health and wellness, recent advancements have enabled these devices to acquire electrocardiogram (ECG) signals, opening up new avenues for remote cardiovascular health monitoring. Notably, they have demonstrated efficacy in detecting conditions such as atrial fibrillation. However, the accuracy of these devices in capturing a broader range of clinically relevant ECG parameters remains uncertain. This study evaluated the accuracy of four popular smartwatch models (Apple Watch Series 9, Samsung Galaxy Watch 6, Fitbit Sense 2, and Withings ScanWatch) in acquiring ECG signals using the standardized testing protocol required for medical electrocardiograph certification. A patient simulator (METRON PS-440) was employed to generate standardized ECG waveforms, which were sequentially recorded by the smartwatches and a reference electrocardiograph (Philips TC30). The devices were assessed by comparing their measurements to the reference standard for key ECG parameters, including heart rate, R-wave amplitude, ST-segment analysis, and response to different waveform types and ranges. Results indicated that all devices exhibited similar patterns to the reference ECG in normal sinus rhythm. Nevertheless, variations were observed in R-wave amplitude and J-point offset measurements, with the Withings device demonstrating the most significant deviations. The Samsung device struggled with heart rates exceeding 100 beats per minute. The Apple Watch and Fitbit Sense 2 demonstrated the most promising performance, suggesting their potential for broader clinical applications beyond basic heart rate monitoring. These devices could be useful in detecting arrhythmias and ischemic heart disease, particularly in remote or resource-constrained settings. • ECG-capable smartwatches offer new opportunities for remote cardiovascular monitoring. • A calibration method for smartwatches is introduced, derived from an IEC standard intended for certifying electrocardiographs for clinical use. • Four smartwatches tested against medical electrocardiograph using standardized certification protocol. • Among the analyzed devices, Apple Watch Series 9 and Fitbit Sense 2 are the smartwatches with the highest potential for clinical use. • This study paves the way for future use of smartwatches for ambulatory monitoring and population screening to detect cardiovascular events early on.