I21.19
BillableST elevation (STEMI) myocardial infarction involving other coronary artery of inferior wall
HCC Category Mapping
V28HCC 228 — Acute Myocardial Infarction
0.000V24HCC 86 — Acute Myocardial Infarction
0.274ESRDHCC 86 — Acute Myocardial Infarction
0.000RxHCCHCC 188 — Coronary Artery Disease and Angina
0.000What This Code Means
A heart attack with ST segment elevation affecting the inferior wall of the heart caused by blockage of a coronary artery other than the right coronary artery.
Coding Tips
- •Use this code when inferior wall STEMI is documented but the culprit vessel is not the RCA
- •Ensure the specific vessel is documented in the medical record to support this code assignment
Clinical Significance
This code captures inferior wall STEMI caused by coronary arteries other than the right coronary artery, such as the left circumflex artery in patients with left-dominant coronary circulation. This distinction is important because treatment approach and prognosis may differ based on the culprit vessel. Accurate vessel identification supports appropriate risk stratification.
Documentation Requirements
- ✓Documentation of STEMI with inferior wall involvement
- ✓Identification of a culprit vessel other than the right coronary artery
- ✓Electrocardiogram showing inferior ST elevation
- ✓Cardiac catheterization or angiography findings
- ✓Cardiac biomarker elevation
- ✓Timing documentation within the 4-week acute window
Excludes 2 — Not included here, may code separately
- ST elevation (STEMI) myocardial infarction involving left circumflex coronary artery (I21.21)
Commonly Confused Codes
I21.11 — STEMI involving right coronary artery: use when the right coronary artery is confirmed as the culpritI21.21 — STEMI involving left circumflex coronary artery: if circumflex is identified, use this more specific codeI21.3 — STEMI of unspecified site: use only when wall location cannot be determinedI22.1 — Subsequent STEMI of inferior wall: for recurrent inferior myocardial infarction within 4 weeks
Code Hierarchy
└I21Acute myocardial infarction└I21.1ST elevation (STEMI) myocardial infarction of inferior wall└I21.19ST elevation (STEMI) myocardial infarction involving other coronary artery of inferior wall
└I21.19ST elevation (STEMI) myocardial infarction involving other coronary artery of inferior wall