Table 1.
Baseline Clinical and ECG Characteristics of the Derivation, Internal Validation, and External Validation Cohorts
| Variable | Derivation and internal validation cohorts (n=51 167) | External validation cohort 1 (n=55 290) | External validation cohort 2 (n=36 650) | P value |
|---|---|---|---|---|
| Clinical characteristics | ||||
| Age, y | 50.56±21.77 | 57.16±17.61 | 52.84±18.93 | <0.001 |
| Men | 25 910 (50.64) | 26 956 (48.75) | 18 903 (51.58) | <0.001 |
| Current smoker | 8284 (16.19) | 4263 (7.71) | 3404 (9.29) | <0.001 |
| Alcohol drinking | 11 124 (21.74) | 5666 (10.25) | 4141 (11.3) | <0.001 |
| Systolic BP, mm Hg | 119.66±15.38 | 123.64±16.52 | 124.77±17.56 | <0.001 |
| Diastolic BP, mm Hg | 74.46±10.69 | 75.71±11.86 | 75.85±12.43 | <0.001 |
| Hypertension | 12 859 (25.13) | 23 181 (41.93) | 11 569 (31.57) | <0.001 |
| Diabetes | 17 489 (34.18) | 19 878 (35.95) | 12 375 (33.77) | <0.001 |
| Dyslipidemia | 13 324 (26.04) | 23 369 (42.27) | 12 548 (34.24) | <0.001 |
| Chronic kidney disease | 942 (1.84) | 2024 (3.66) | 1345 (3.67) | <0.001 |
| Thyroid disease | 1035 (2.02) | 2334 (4.22) | 2933 (8) | <0.001 |
| COPD | 48 (0.09) | 1051 (1.9) | 237 (0.65) | <0.001 |
| Heart failure | 417 (0.81) | 615 (1.11) | 568 (1.55) | <0.001 |
| VHD | ||||
| MV stenosis | 22 (0.04) | 40 (0.07) | 28 (0.08) | <0.001 |
| Other VHD | 128 (0.25) | 226 (0.41) | 83 (0.23) | |
| Coronary artery disease | 3157 (6.17) | 7449 (13.47) | 3339 (9.11) | <0.001 |
| Stroke | 2423 (4.74) | 3357 (6.07) | 1665 (4.54) | <0.001 |
| Peripheral arterial disease | 194 (0.38) | 759 (1.37) | 598 (1.63) | <0.001 |
| ECG diagnosis (top 20) | ||||
| Normal sinus rhythm | 19 537 (38.18) | 25 129 (45.45) | 7779 (21.23) | <0.001 |
| Sinus rhythm (bradycardia) | 3676 (7.18) | 5717 (10.34) | 1356 (3.7) | <0.001 |
| T wave (abnormal) | 2478 (4.84) | 3498 (6.33) | 1413 (3.86) | <0.001 |
| Sinus rhythm | 2430 (4.75) | 3000 (5.43) | 3698 (10.09) | <0.001 |
| LVH | 1288 (2.52) | 1955 (3.54) | 938 (2.56) | <0.001 |
| Sinus rhythm (tachycardia) | 1174 (2.29) | 1649 (2.98) | 797 (2.17) | <0.001 |
| QT interval (prolonged) | 1048 (2.05) | 1305 (2.36) | 719 (1.96) | <0.001 |
| Sinus arrhythmia | 944 (1.84) | 746 (1.35) | 431 (1.18) | <0.001 |
| Left‐axis deviation | 901 (1.76) | 1359 (2.46) | 535 (1.46) | <0.001 |
| Right‐axis deviation | 869 (1.7) | 912 (1.65) | 441 (1.2) | <0.001 |
| Atrioventricular block (first degree) | 838 (1.64) | 1535 (2.78) | 480 (1.31) | <0.001 |
| Atrioventricular block | 825 (1.61) | 1557 (2.82) | 291 (0.79) | <0.001 |
| Myocardial infarction (inferior) | 799 (1.56) | 1249 (2.26) | 383 (1.05) | <0.001 |
| Myocardial ischemia (lateral) | 762 (1.49) | 1067 (1.93) | 387 (1.06) | <0.001 |
| ST‐T abnormality (nonspecific) | 652 (1.27) | 1205 (2.18) | 287 (0.78) | <0.001 |
| RBBB | 636 (1.24) | 978 (1.77) | 278 (0.76) | <0.001 |
| Myocardial ischemia (anterior) | 607 (1.19) | 750 (1.36) | 301 (0.82) | <0.001 |
| Early repolarization | 477 (0.93) | 690 (1.25) | 522 (1.42) | <0.001 |
| Ventricular premature complex | 442 (0.86) | 927 (1.68) | 225 (0.61) | <0.001 |
| ST‐segment elevation | 334 (0.65) | 529 (0.96) | 464 (1.27) | <0.001 |
Values are presented as number (percentage) or mean±SD. BP indicates blood pressure; COPD, chronic obstructive pulmonary disease; LVH, left ventricular hypertrophy; MV, mitral valve; RBBB, right bundle‐branch block; and VHD, valvular heart disease.