I21.A1 Myocardial infarction type 2
The ICD-10-CM code for Myocardial infarction type 2 is I21.A1 (FY2026). It is a billable, claim-ready diagnosis code.
Classification
- Section
- I20-I25: Ischemic heart diseases (I20-I25)
- Category I21
- 18 codes (13 billable)
- FY2026 Status
- Stable since FY2024
Also Known As
ICD-10-CM Alphabetic Index entries that lead to I21.A1:
- Infarct, infarction › myocardium, myocardial (acute) (with stated duration of 4 weeks or less) › type 2
- Ischemia, ischemic › demand (coronary) › with myocardial infarction
- Ischemia, ischemic › demand (coronary) › resulting in myocardial infarction
- Infarct, infarction › myocardium, myocardial (acute) (with stated duration of 4 weeks or less) › due to › ischemic imbalance
- Infarct, infarction › myocardium, myocardial (acute) (with stated duration of 4 weeks or less) › subsequent (recurrent) (reinfarction) › type 2
- Infarct, infarction › myocardium, myocardial (acute) (with stated duration of 4 weeks or less) › secondary to › ischemic imbalance
- Infarct, infarction › myocardium, myocardial (acute) (with stated duration of 4 weeks or less) › due to › demand ischemia
- Infarct, infarction › myocardium, myocardial (acute) (with stated duration of 4 weeks or less) › secondary to › demand ischemia
Inclusion Terms
- Myocardial infarction due to demand ischemia
- Myocardial infarction secondary to ischemic imbalance
U.S. Hospital Utilization
- An estimated 623,115 U.S. inpatient stays in 2023 included I21.A1 among the documented diagnoses.
- 6,055 stays listed it as the principal diagnosis.
Source: National Inpatient Sample (NIS), Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality, 2016–2023. National survey-weighted estimates.
Official Coding Guidelines
Do not use I22 for subsequent MI other than type 1/unspecifiedDo not assign code I22 for subsequent myocardial infarctions other than type 1 or unspecified. For subsequent type 2 AMI assign only code I21.A1. For subsequent type 4 or type 5 AMI, assign only code I21.A9.
Type 2 MI: assign I21.A1; code underlying cause first; do not use I24.89Type 2 myocardial infarction (myocardial infarction due to demand ischemia or secondary to ischemic imbalance) is assigned to code I21.A1, Myocardial infarction type 2 with the underlying cause coded first, if applicable. Do not assign code I24.89, Other forms of acute ischemic heart disease, for the demand ischemia. If a type 2 AMI is described as NSTEMI or STEMI, only assign code I21.A1. Codes I21.01-I21.4 should only be assigned for type 1 AMIs.
Source: CMS — ICD-10-CM Official Guidelines for Coding and Reporting, FY2026