I21.A9: Other myocardial infarction type
I21.A9 is a billable, specific ICD-10-CM code for other myocardial infarction type. It is valid for submission on a claim.
Check I21.A9 with the rest of the claim: free scrubberCode first
The underlying condition must be sequenced before this code.
Code also
Both codes may be needed to describe the encounter fully. Sequencing depends on the reason for the visit.
- complication, if known and applicable, such as:
- (acute) stent occlusion (T82.897-)
- (acute) stent stenosis (T82.855-)
- (acute) stent thrombosis (T82.867-)
- cardiac arrest due to underlying cardiac condition (I46.2)
- complication of percutaneous coronary intervention (PCI) (I97.89)
- occlusion of coronary artery bypass graft (T82.218-)
Inclusion terms
Alternative wordings a physician may use in the chart for this same code.
- Myocardial infarction associated with revascularization procedure
- Myocardial infarction type 3
- Myocardial infarction type 4a
- Myocardial infarction type 4b
- Myocardial infarction type 4c
- Myocardial infarction type 5
Other codes that can never be billed with I21.A9
Their own Excludes1 notes name this code, so the conflict is not listed above.
Risk adjustment
I21.A9 risk-adjusts. Under the CMS-HCC V28 model it maps to this category:
- HCC 228 Acute Myocardial Infarction0.252 RAF
Coefficient shown for the Community Non-dual Aged segment. A higher HCC in the same hierarchy will suppress this one, so capturing it does not always add score. Look up the whole chart to see which of its HCCs the hierarchy would zero.
Medicare coverage
I21.A9 is named in 33 Medicare coverage policies: 33 listing it as supporting medical necessity. Which one applies depends on your Medicare contractor.
- A52850Billing and Coding: Cardiac Catheterization and Coronary Angiography
- A56423Billing and Coding: Cardiology Non-emergent Outpatient Stress Testing
- A56476Billing and Coding: Cardiac Radionuclide Imaging
- A56605Billing and Coding: B-type Natriuretic Peptide (BNP) Testing
Alphabetic index entries that lead here
- Infarct, infarction›myocardium, myocardial›associated with revascularization procedure
- Infarct, infarction›myocardium, myocardial›type 3
- Infarct, infarction›myocardium, myocardial›type 4(a) (b) (c)
- Infarct, infarction›myocardium, myocardial›type 5
- Infarct, infarction›myocardium, myocardial›subsequent›type 3
- Infarct, infarction›myocardium, myocardial›subsequent›type 4
- Infarct, infarction›myocardium, myocardial›subsequent›type 5
Code history
Unchanged in every release from FY2024 to FY2027.