It can be a tall T wave and the cause includes hyperkalaemia (too much potassium
in the blood), hyperacute myocardial infarction (heart attack...heart muscle damage) and
left bundle branch block (causes arrhythmia). Usually requires other abnormal wave forms in addition to the t wave abnormality.
Causes of small, flattened or inverted T waves are numerous and include ISCHEMIA (blocked or partially blocked arteries), age, race, hyperventilation, anxiety, drinking iced water, LVH, drugs (e.g.