ICD-10 Code I22.1 – Subsequent ST elevation (STEMI) myocardial infarction of inferior wall (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code I22.1 – Subsequent ST elevation (STEMI) myocardial infarction of inferior wall
What it is
This code identifies a new ST-elevation myocardial infarction affecting the inferior wall that occurs after a recent acute myocardial infarction. Use it when documentation shows a subsequent, not initial, infarction episode.
Clinical signs
Typical findings include ischemic chest discomfort, ECG evidence of ST elevation in inferior leads, and clinical confirmation of myocardial injury. Clinical features vary; refer to documentation.
When to use this code
Use I22.1 when the record states a subsequent STEMI involving the inferior wall during the acute phase after a recent MI. Apply it when the provider clearly documents reinfarction or a new infarct, not a continuation of the original event.
Check that the inferior-wall location is specified in the note, ECG interpretation, or discharge summary. If the documentation only says “myocardial infarction” or does not confirm a subsequent event, check documentation.
Do not use for
Do not use this code for the initial acute STEMI or for old, healed, or unspecified infarction. Do not assign it when the inferior-wall site or subsequent timing is not documented.
Coding tip
Confirm both elements: a subsequent MI and inferior-wall STEMI, because either missing detail changes code selection.