when my uncle had heart attack the doctors told immediately by looking at the ECG when he was rushed to emergency with chest pain. my friends dad also had chest pain and was taken to emergency room and they said the ECG is in conclusive and ordered a blood test. latter it was told that that test is also not convincing. they ordered for other blood tests and told probably he had heart attack and it took 8 hours for them to tell this. now i wonder how many tests are there to detect heart attack.