Final answer:
An ECG taken 6 hours after an MI commonly shows an elevated ST segment and an enlarged Q wave, indicative of a STEMI. Blood tests also contribute to confirming the diagnosis with elevated creatine kinase MB and cardiac troponin levels.
Step-by-step explanation:
The sign of a myocardial infarction (MI) on an electrocardiogram (ECG) 6 hours later typically includes alterations in the ST segment and the Q wave. An elevation of the ST segment is generally indicative of an acute MI and is classified as ST-elevated MI (STEMI). Additionally, an enlarged Q wave can indicate that a myocardial infarction has occurred. Blood tests may show elevated levels of creatine kinase MB and cardiac troponin, released by damaged cardiac cells.
Interpreting the ECG will not reveal the effectiveness of heart pumping or the severity of the damage to the heart tissue, which would require further tests such as echocardiography or cardiac magnetic resonance imaging for a more comprehensive evaluation.