ICD-10 Code I21.19 – ST elevation (STEMI) myocardial infarction involving other coronary artery of inferior wall (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code I21.19 – ST elevation (STEMI) myocardial infarction involving other coronary artery of inferior wall
What it is
This code identifies an acute ST-elevation myocardial infarction affecting an inferior wall territory supplied by a coronary artery other than the main named vessels in standard coding options. Use it when the record specifies this exact location.
Clinical signs
Typical findings include acute ischemic chest pain, electrocardiographic ST elevation, and evidence of myocardial injury. Clinical features vary; refer to documentation for the documented coronary artery and infarct location.
When to use this code
Use I21.19 when the provider documents a STEMI involving the inferior wall and names an other coronary artery. It is appropriate for the initial acute event, not for a past history of infarction. If the artery or wall location is unclear, check documentation.
Do not use for
Do not use this code for non-ST-elevation myocardial infarction, unspecified acute MI, or an inferior wall STEMI involving a different specifically indexed coronary artery. Check documentation if the record does not clearly support this exact diagnosis.
Coding tip
Code from the provider’s exact anatomic wording; if “other coronary artery” is not documented, do not assume I21.19.