ICD-10 Code I21.29 – ST elevation (STEMI) myocardial infarction involving other sites (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code I21.29 – ST elevation (STEMI) myocardial infarction involving other sites
What it is
This code identifies an acute ST-elevation myocardial infarction affecting cardiac sites other than the common locations named in more specific STEMI codes. Use it when the record clearly documents STEMI involving “other sites.”
Clinical signs
Typical findings include acute chest pain or ischemic equivalents with ECG evidence of ST elevation consistent with myocardial infarction. Clinical features vary; refer to documentation.
When to use this code
Use I21.29 when the provider documents a STEMI and specifies involvement of other sites, without a more precise site code. It also fits when the diagnosis is confirmed and the location is clearly described as “other.” Check documentation if the infarct site is uncertain.
Do not use for
Do not use this code for NSTEMI, old myocardial infarction, or unspecified acute MI. If the record names a different STEMI site, code that more specific category instead.
Coding tip
Code the exact infarct site from the provider’s documentation and query if “other sites” is vague.