Clinical evaluation of a spot-check ECG for the diagnosis of atrial fibrillation

Background: Opportunistic screening of atrial fibrillation (AF) using wearable spot-check electrocardiogram (ECG) devices has emerged for early detection, yet remains limited by concerns for accuracy and false positives. Objective: This study aimed to assess the Masimo W1 wrist-wearable ECG spot-check device in detecting AF and normal sinus rhythm (NSR) while rendering diagnostic ECG waveform quality to support physician overread. Methods: Participants with and without a previous AF diagnosis were prospectively enrolled across 4 US sites to compare the AF and NSR detection performance between the Masimo W1 ECG and a 12-lead ECG reference, plus concordance of clinically relevant ECG waveform features assessed by blinded reviewers. Results: Among 356 participants (mean age 56 years; 60% female), 169 (47.5%) were in NSR and 165 (46.3%) in AF, whereas 22 were excluded as noise outputs (1.7%) or other rhythms (4.5%). Sensitivity and specificity for automated AF detection were 99.3% (95% confidence interval [CI] 96.3-100) and 100% (95% CI 97.8-100), respectively. The inconclusive rate was 5%. AF and NSR detection probabilities were 89.7% and 99.4%, respectively. Qualitative comparison demonstrated 99% (95% CI 98-100.0) agreement with the reference ECG across reviewers and records. Quantitative analysis of ECG waveform features showed a high correlation between the Masimo W1 ECG and lead I of the 12-lead ECG for diagnosing AF. Conclusion: The Masimo W1 ECG demonstrated highly accurate automated AF detection, few noise classifications, and exceptional NSR detection to mitigate concerns over false positives. Qualitative preservation of ECG waveform features supports the requisite physician overread required by practice guidelines.