Are q and t waves inversion on ekg an indication of a past heart attack?

Possibly: Abnormal ekg's (ecg's) are one diagnostic criteria for prior heart attacks. However, these changes can also be seen in hypertension, cardiomyopathies, pulmonary disease, and even in normal hearts.

Depends: Depends on which leads they're in. Q wave can be indicative of past heart attack but also depends on the depth and width of q wave. Some Q waves are normal and called "septal qs".

Yes: A q wave usually means a past infarct - death of that part of the heart from a heart attack. An inverted t can mean past ischemia - severely reduced blood flow that stunned the heart muscle but didn't result in cell death - also due to a heart attack.