Which of the following is NOT one of the common tests used to diagnose a myocardial infarction?

The complete blood count (CBC) is indeed not one of the common tests used specifically to diagnose a myocardial infarction (MI). While a CBC can provide valuable information about overall health and detect various conditions, including inflammation or infection, it does not directly assess cardiac muscle damage.

In the context of diagnosing a myocardial infarction, cardiac enzymes such as troponins and creatine kinase MB (CK-MB) are crucial tests. These enzymes are released into the bloodstream when there is damage to the heart muscle, making them key indicators for diagnosing MI. An electrocardiogram (ECG or EKG) is also a standard diagnostic tool used to assess heart rhythm and electrical activity, often revealing changes associated with a heart attack. Electrolytes may be checked as well to evaluate the balance of essential minerals in the body, which can affect heart function, but they do not directly diagnose MI.

Therefore, among the provided options, the complete blood count stands out as the one that is not typically used as a direct diagnostic tool for myocardial infarction, focusing instead on other areas of health.