My Dad Recently Went To The Hospital And Had Troponin

My dad recently went to the hospital and had troponin readings levels of .04 , .11 and .08 (every 6 hours sequentially) and he was released from the hospital without being diagnosed with a heart attack. He died 20 days later in his sleep from an apparent heart attack. He had all the symptoms of a heart attack when we went to the hospital - chest pain , heartburn , radiant pain in his arms , back , jaw and shoulders. My question is shouldn't a troponin reading of .11 indicate he had some sort of heart damage ? All his other test came out fine - EKG , stress test , blood pressure,cholesterol .