ICD-9-CM diagnosis code (retired)
410.91 — Acute myocardial infarction of unspecified site, initial episode of care
ICD-9-CM was replaced by ICD-10 on October 1, 2015. These are the ICD-10-CM equivalents from the CMS General Equivalence Mappings.
About ICD-9-CM 410.91
410.91 is an ICD-9-CM diagnosis code for acute myocardial infarction of unspecified site, initial episode of care. ICD-9-CM was retired for U.S. claims on October 1, 2015, when ICD-10-CM took over.
The CMS General Equivalence Mappings translate it to 4 ICD-10-CM codes, such as I21.3 (ST elevation (STEMI) myocardial infarction of unspecified site), I21.9 (Acute myocardial infarction, unspecified) and I21.A1 (Myocardial infarction type 2). All of these are approximate matches, so review the record to pick the right one.
ICD-10-CM equivalents
Common questions about 410.91
GEMs are a translation aid, not a substitute for coding from the record. The 2027 ICD-10 code set has changed since the last GEMs release in 2018. Page updated September 29, 2026.