Question: What kinds of changes did we see in MI codes due to ICD-10 2018? Oregon Subscriber Answer: When it comes to ICD-10 2018, you should look for revisions to the I21- range. This category's name changed from "ST elevation and non-ST elevation myocardial infarction" to the heading, "Acute myocardial infarction." Several subcodes under this new heading will help cardiologists better describe the type of myocardial infarction the patient experienced. Example: I21.0 (ST elevation (STEMI) myocardial infarction of anterior wall) refers to STEMI of the anterior wall, while I21.1 (ST elevation (STEMI) myocardial infarction of inferior wall) describes STEMI of the inferior wall. Notes under both codes indicate that these codes refer to "Type 1" STEMI. You'll also see a new AMI code - I21.9 (Acute myocardial infarction, unspecified). And, I21.A (Other type of myocardial infarction) has a new subcategory that contains the following new codes: