Troponin-T is preferable to CPK-MB in the diagnosis of acute myocardial infraction in all the following situations except

Ref Harrison 19 th ed pg 1594 Because of cardiac troponins are elevated for prolonged periods an episode of recurrent ischemia after four days would be more readily diagnosed with a marker that remains elevated in blood more briefly such as CK-MB which returns to normal levels by 72 hours .