Comparison of 6-lead smartphone ECG and 12-lead ECG in athletes and a genetic heart disease population

Background: Smartphone electrocardiograms (iECGs) are an innovative method of capturing transient arrhythmias that are occasionally experienced by athletes. This study aimed to assess the accuracy of a 6-lead iECG compared with 12-lead ECG in athletes and those with known genetic heart disease (positive controls). Research design and methods: Each participant had a resting 12-lead ECG (supine) and a 30 s 6-lead iECG (seated) taken within 2 h. Manual measurements of heart rate, QTc, and PR intervals, and QRS duration were completed using digital calipers. Bland-Altman analysis was used to assess the quantitative agreement of measurements. Results: The 6-lead readings for heart rate were faster than the 12-lead in athletes (n = 233) and positive controls (n = 49). All other measurements were shorter in the 6-lead. QTc mean difference was smaller in the positive controls (4.7 ± 26.0 ms) than in athletes (12.5 ± 25.0 ms). The largest difference was in PR intervals, both in athletes (12.8 ± 17.7 ms) and positive controls (7.6 ± 18.9 ms). QRS duration had the smallest mean difference (0.6 ± 9.0 ms in athletes, 1.0 ± 12.7 ms in positive controls). Conclusions: The 6-lead readings had reasonable agreement with the 12-lead ECG. A 6-lead iECG is a reasonable option to opportunistically capture arrhythmias that may occur infrequently, but should not replace a 12-lead if available.