ECG characteristics of adolescent black athletes, white athletes and black controls
| Parameter | BA (n = 329) | WA (n = 903) | BC (n = 134) | p Value BA vs WA | p Value BA vs BC |
|---|---|---|---|---|---|
| Sinus bradycardia* | 41.9% | 58.0% | 16.4% | <0.001 | <0.001 |
| 1st-degree AV block | 8.9% | 2.5% | 0.7% | <0.001 | 0.001 |
| QRS duration (ms) | 87 ± 11 | 94 ± 10 | 86 ± 8 | <0.001 | 0.340 |
| QTc (ms) | 398 ± 23 | 403 ± 22 | 405 ± 22 | <0.001 | 0.003 |
| Partial RBBB | 18.5% | 18.2% | 3.0% | 0.868 | <0.001 |
| RBBB | 0.3% | 0.2% | 0% | 0.569 | 1.000 |
| LBBB | 0% | 0% | 0% | – | – |
| LAD | 1.8% | 0.8% | 1.5% | 0.051 | 1.000 |
| RAD | 0.3% | 1.4% | 0.7% | 0.130 | 0.496 |
| Pathological Q-waves | 0.0% | 0.3% | 0.0% | 1.000 | – |
| LA enlargement | 7.6% | 3.7% | 3.7% | 0.006 | 0.148 |
| RA enlargement | 3.0% | 0.4% | 1.5% | 0.001 | 0.522 |
| LVH | 20.1% | 32.2% | 29.9% | <0.001 | 0.025 |
| RVH | 16.4% | 8.2% | 3.0% | <0.001 | <0.001 |
| Inverted T-waves | 22.8% | 4.5% | 13.4% | <0.001 | 0.026 |
| T-wave inversions in V1–V4 | 14.3% | 2.5% | 11.9% | <0.001 | 0.553 |
| T-wave inversions limited to V1–V2 | 3.6% | 2.3% | 10.4% | 0.231 | <0.001 |
| T-wave inversions in inferior leads | 6.1% | 1.7% | 1.5% | <0.001 | 0.037 |
| T-wave inversions in lateral leads | 2.4% | 0.3% | 0.7% | <0.001 | 0.074 |
| Deep T-wave inversions | 6.7% | 0.2% | 0.7% | <0.001 | 0.003 |
| ST-segment elevation | 49.5% | 20.2% | 47.8% | <0.001 | 0.759 |
| ST-segment depression | 0.6% | 0% | 0% | 0.071 | – |
Where applicable, results are expressed as percentages or mean ± SD.
*Heart rate < 60 beats∕min.
AV, atrioventricular; BA, black athletes; BC, black controls; LA, left atrial; LAD, left axis deviation; LBBB, left bundle branch block; LVH, left ventricular hypertrophy; QTc, corrected QT-interval using Bazett's formula; RA, right atrial; RAD, right axis deviation; RBBB, right bundle branch block; RVH, ECG right ventricular hypertrophy; WA, white athletes.