| QTc interval | P wave | PR interval | QRS complex | ST interval | T wave | Arrhythmias |
| HCM | ||||||
| Normal | (Left atrial enlargement) | Normal | Increased voltages in mid-left precordial leads; abnormal Q waves in inferior and/or lateral leads; (LAD, LBBB); (delta wave) | Down-sloping (up-sloping) | Inverted in mid-left precordial leads; (giant and negative in the apical variant) | (Atrial fibrillation); (PVB); (VT) |
| Arrhythmogenic right ventricular cardiomyopathy/dysplasia | ||||||
| Normal | Normal | Normal | Prolonged >110 ms in right precordial leads; epsilon wave in right precordial leads; reduced voltages ≤0.5 mV in frontal leads; (RBBB) | (Up-sloping in right precordial leads) | Inverted right in precordial leads | PVB with an LBBB pattern; (VT with an LBBB pattern) |
| Dilated cardiomyopathy | ||||||
| Normal | (Left atrial enlargement) | (Prolonged ≥0.21 s) | LBBB | Down-sloping (up-sloping) | Inverted in inferior and/or lateral leads | PVB; (VT) |
| Long QT syndrome | ||||||
| Prolonged | Normal | Normal | Normal | Normal | Bifid or biphasic in all leads | (PVB); (torsade de pointes) |
| >440 ms in males | ||||||
| >460 ms in females | ||||||
