If an acute myocardial infarction (AMI) is documented as nontransmural or subendocardial with a site provided, how is it coded?

When coding for an acute myocardial infarction (AMI) that is specified as nontransmural or subendocardial with a site indicated, it is important to select the appropriate code that reflects the nature of the infarction and its characteristics.

The term "subendocardial" refers to a type of AMI that affects only a portion of the heart muscle, specifically the inner layer or the endocardium, rather than involving the entire thickness of the heart wall, as seen in transmural infarctions. In ICD-10-CM coding, this specific characterization directly corresponds to the coding guidelines for myocardial infarctions, making it clear that the correct code should express this condition.

In the context of the other choices, while NSTEMI (Non-ST Elevation Myocardial Infarction) might seem relevant, it includes a specific cardiac marker related to the level of ST elevation on an ECG, which does not precisely align with the description of a nontransmural event as noted. Similarly, the options related to ST elevation and a general unspecified code do not accurately encompass the specific nature of a subendocardial AMI with a site provided.

Using the designated coding conventions, subendocardial AMI should be identified