The presence of high levels of cardiac troponin T in a patient generally indicates damage to the heart muscle. Among the options listed, the most likely diagnosis associated with elevated cardiac troponin levels is Acute myocardial infarction.
While angina can be caused by transient ischemia without permanent damage, it typically does not result in elevated troponin levels unless it progresses to myocardial infarction. Atrioventricular block and transient cardiac ischemia are not typically directly associated with elevated cardiac troponin levels either.
Therefore, the best diagnosis in this context is:
Acute myocardial infarction.