What code is assigned to acute myocardial infarctions types 3, 4a, 4b, 4c, and 5?

The assignment of code I21.A9 is appropriate for acute myocardial infarction types 3, 4a, 4b, 4c, and 5. In the ICD-10-CM coding system, the category I21 refers specifically to types of acute myocardial infarction. The codes following I21 are used to distinguish the various types and circumstances of myocardial infarctions.

I21.A9 is designated for unspecified acute myocardial infarction, which encompasses those specific types (3, 4a, 4b, 4c, and 5). This code reflects the importance of specificity in identifying the nature of the myocardial infarction and allows healthcare providers to document these events adequately for treatment and epidemiological tracking.

In contrast, the other codes do not pertain directly to the classifications of myocardial infarction. N18.2, for instance, is related to chronic kidney disease, and I13 involves heart diseases secondary to hypertension, both of which fall outside the context of the question regarding myocardial infarctions. Thus, I21.A9 stands out as the correct designation.