T wave inversion is a feature of myocardial infarction and angina. If an infarction is not full-thickness then there will be T wave inversion but no Q waves. This condition is described as a subendocardial infarction.
In ventricular hypertrophy then there may be T wave inversion in the leads that look at the respective ventricle, ie V5, V6, II and VL looking at the left ventricle, and, V1, V2 and V3 looking at the right ventricle.
Digoxin administration causes T wave inversion, particularly with sloping depression of the ST segment. Thus it is useful to record an ECG before beginning digitalis to save later confusion about the significance of T wave changes.