Table 3.
Bland–Altman analysis between the standard 12-lead and handheld 6-lead ECGs in different acquisition positions
| Supine position (107 pairs) | ||||||
|---|---|---|---|---|---|---|
| Metric | N | Mean difference | SD | Upper LOA | Lower LOA | Outliers N (%) |
| Heart rate (bpm) | 107 | 0.03 | 1.12 | 2.23 | − 2.17 | 8 (7.5) |
| PR interval (ms) | 63 | 12.06 | 13.86 | 39.23 | − 15.11 | 2 (3.2) |
| QRS duration (ms) | 107 | − 6.38 | 14.89 | 22.80 | − 35.57 | 6 (5.6) |
| QT interval (ms) | 107 | − 10.34 | 22.68 | 34.11 | − 54.79 | 6 (5.6) |
| QTc interval (ms) | 107 | − 11.52 | 26.36 | 40.16 | − 63.19 | 4 (3.7) |
| P amplitude (mV) | 63 | − 0.01 | 0.05 | 0.08 | − 0.11 | 3 (4.8) |
| QRS amplitude (mV) | 107 | 0.04 | 0.11 | 0.26 | − 0.18 | 9 (8.4) |
| T amplitude (mV) | 107 | − 0.01 | 0.05 | 0.09 | − 0.10 | 2 (1.9) |
| Sitting position (109 pairs) | ||||||
|---|---|---|---|---|---|---|
| Metric | N | Mean difference | SD | Upper LOA | Lower LOA | Outliers N (%) |
| Heart rate (bpm) | 109 | 0.03 | 1.24 | 2.46 | − 2.40 | 8 (7.3) |
| PR interval (ms) | 61 | 7.39 | 16.88 | 40.47 | − 25.69 | 4 (6.6) |
| QRS duration (ms) | 109 | − 6.04 | 15.28 | 23.91 | − 35.99 | 3 (2.8) |
| QT interval (ms) | 109 | − 5.32 | 25.27 | 44.21 | − 54.85 | 6 (5.5) |
| QTc interval (ms) | 109 | − 6.41 | 30.57 | 53.50 | − 66.33 | 2 (1.8) |
| P amplitude (mV) | 61 | 0.01 | 0.04 | 0.08 | − 0.07 | 4 (6.6) |
| QRS amplitude (mV) | 109 | 0.04 | 0.07 | 0.18 | − 0.09 | 6 (5.5) |
| T amplitude (mV) | 109 | 0.00 | 0.05 | 0.10 | − 0.09 | 6 (5.5) |
Negative values indicated higher measurements from the 6-lead ECG. LOA was calculated using the mean difference and SD. The upper LOA was defined as the mean difference plus 1.96*SD, and the lower LOA was defined as the mean difference minus 1.96*SD. Cases without identifiable P waves were excluded from PR interval and P amplitude analyses.
ECG electrocardiogram, SD standard deviation, LOA limits of agreement, bpm beats per minute, ms milliseconds, mV millivolts