I21.21Billable
ST elevation (STEMI) myocardial infarction involving left circumflex coronary artery
Short description: STEMI involving left circumflex coronary artery
- Chapter
- 9. Diseases of the circulatory system
- Category
- I21
- Effective date
- October 1, 2026
Related codes in category I21
I21Acute myocardial infarctionI21.0ST elevation (STEMI) myocardial infarction of anterior wallI21.01STEMI involving left main coronary arteryYesI21.02STEMI involving left anterior descending coronary arteryYesI21.09STEMI involving oth coronary artery of anterior wallYesI21.1ST elevation (STEMI) myocardial infarction of inferior wallI21.11STEMI involving right coronary arteryYesI21.19STEMI involving oth coronary artery of inferior wallYesI21.2ST elevation (STEMI) myocardial infarction of other sitesI21.29STEMI involving oth sitesYesI21.3ST elevation (STEMI) myocardial infarction of unsp siteYesI21.4Non-ST elevation (NSTEMI) myocardial infarctionYes
Frequently asked questions
What is ICD-10 code I21.21?
I21.21 is an ICD-10-CM diagnosis code for ST elevation (STEMI) myocardial infarction involving left circumflex coronary artery.
Is I21.21 a billable code?
Yes. I21.21 is billable and specific enough to be used on a claim.
What ICD-10-CM chapter is I21.21 in?
I21.21 falls under Chapter 9: Diseases of the circulatory system.
When did I21.21 become effective?
I21.21 has been effective since October 1, 2026, per the CMS/CDC ICD-10-CM annual release.
What other codes are related to I21.21?
I21.21 belongs to category I21, which includes 12 other codes — see the related codes list on this page.
ICD-10-CM data maintained by CDC/CMS (public domain). Always verify codes with authoritative sources before making coding or billing decisions.