| Normal ECG findings in athletes | |
| 1. Sinus bradycardia (≥30 bpm) | |
| 2. Sinus arrhythmia | |
| 3. Ectopic atrial rhythm | |
| 4. Junctional escape rhythm | |
| 5. 1° AV block (PR interval >200 ms) | |
| 6. Mobitz Type I (Wenckebach) 2° AV block | |
| 7. Incomplete RBBB | |
8. Isolated QRS voltage criteria for LVH
| |
| 9. Early repolarization (ST elevation, J-point elevation, J-waves, or terminal QRS slurring) | |
| 10. Convex ("domed") ST segment elevation combined with T-wave inversion in leads V1–V4 in black/African athletes | |
| These common training-related ECG alterations are physiological adaptations to regular exercise, considered normal variants in athletes and do not require further evaluation in asymptomatic athletes | |
| Abnormal ECG findings in athletes | |
| Abnormal ECG finding | Definition |
| T-wave inversion | >1 mm in depth in two or more leads V2–V6, II and aVF, or I and aVL (excludes III, aVR and V1) |
| ST segment depression | ≥0.5 mm in depth in two or more leads |
| Pathologic Q waves | >3 mm in depth or >40 ms in duration in two or more leads (except for III and aVR) |
| Complete left bundle branch block | QRS ≥120 ms, predominantly negative QRS complex in lead V1 (QS or rS), and upright monophasic R wave in leads I and V6 |
| Intraventricular conduction delay | Any QRS duration ≥140 ms |
| Left axis deviation | –30° to –90° |
| Left atrial enlargement | Prolonged P wave duration of >120 ms in leads I or II with negative portion of the P wave ≥1 mm in depth and ≥40 ms in duration in lead V1 |
| Right ventricular hypertrophy pattern | R–V1+S–V5 >10.5 mm AND right axis deviation >120° |
| Ventricular pre-excitation | PR interval <120 ms with a delta wave (slurred upstroke in the QRS complex) and wide QRS (>120 ms) |
| Long QT interval* | QTc ≥470 ms (male) QTc ≥480 ms (female) QTc ≥500 ms (marked QT prolongation) |
| Short QT interval* | QTc ≤320 ms |
| Brugada-like ECG pattern | High take-off and downsloping ST segment elevation followed by a negative T wave in ≥2 leads in V1–V3 |
| Profound sinus bradycardia | <30 bpm or sinus pauses ≥3 s |
| Atrial tachyarrhythmias | Supraventricular tachycardia, atrial fibrillation, atrial flutter |
| Premature ventricular contractions | ≥2 PVCs per 10 s tracing |
| Ventricular arrhythmias | Couplets, triplets, and non-sustained ventricular tachycardia |
