Table 1

Abnormal ECG findings suggestive of primary electrical disease

Abnormal ECG FindingDefinition
Ventricular pre-excitationPR 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 patternHigh 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 tachyarrhythmiasSupraventricular tachycardia, atrial-fibrillation, atrial-flutter
Premature ventricular contractions≥2 PVCs per 10 s tracing
Ventricular arrhythmiasCouplets, triplets, and non-sustained ventricular tachycardia
  • Note: These ECG findings are unrelated to regular training or expected physiological adaptation to exercise, may suggest the presence of pathological cardiovascular disease, and require further diagnostic evaluation.

  • *The QT interval corrected for heart rate is ideally measured with heart rates of 60–90 bpm. Consider repeating the ECG after mild aerobic activity for borderline or abnormal QTc values with a heart rate <50 bpm.