| Ischemic causes |
| Hyperacute phase of myocardial infarction |
| Acute transient transmural ischemia (Prinzmetal's angina) |
| Chronic (evolving) phase of myocardial infarction (tall positive T waves reciprocal to primary deep T wave inversions) |
| Nonischemic causes |
| Normal variants ("early repolarization" patterns) |
| Hyperkalemia |
| Acute hemopericardium |
| Cerebrovascular hemorrhage (more commonly T wave inversions) |
| Left ventricular hypertrophy |
| Right precordial leads, usually in conjunction with left precordial ST depressions and T wave inversions |
| Left precordial leads, particularly in association with "diastolic" volume overload conditions |
| Left bundle branch block (right precordial leads) |
| Acute pericarditis (occasionally) |
