ICD-10 Code I21.0 – ST elevation (STEMI) myocardial infarction of anterior wall (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code I21.0 – ST elevation (STEMI) myocardial infarction of anterior wall
What it is
This code identifies an acute ST-elevation myocardial infarction affecting the anterior wall of the heart. Use it when documentation specifies an anterior-wall STEMI or anteroseptal infarction.
Clinical signs
Typical findings include acute chest pain, ischemic ECG changes with ST elevation in anterior leads, and evidence of myocardial injury. Clinical features vary; refer to documentation.
When to use this code
Use I21.0 when the provider documents a STEMI of the anterior wall, including anterior or anteroseptal involvement. Code it from the confirmed diagnosis, not from suspected chest pain alone. If the record is unclear about the infarct location, check documentation before assigning this code.
Do not use for
Do not use this code for NSTEMI, old myocardial infarction, or chest pain without documented infarction. Do not assume anterior wall involvement unless the provider states it.
Coding tip
Match the infarct location exactly as documented, and query the provider if STEMI is confirmed but the wall location is missing.