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I21.A1

I21.A1: Myocardial infarction type 2

Billable / specific codeICD-10-CM

I21.A1 is a billable, specific ICD-10-CM code for myocardial infarction type 2. It is valid for submission on a claim.

Check I21.A1 with the rest of the claim: free scrubber

Code first

The underlying condition must be sequenced before this code.

  • , if applicable, the underlying cause, such as:
  • anemia (D50.0-D64.9)
  • chronic obstructive pulmonary disease (J44.-)
  • paroxysmal tachycardia (I47.0-I47.9)
  • shock (R57.0-R57.9)

Inclusion terms

Alternative wordings a physician may use in the chart for this same code.

  • Myocardial infarction due to demand ischemia
  • Myocardial infarction secondary to ischemic imbalance

Excludes2 inherited from the categories above I21.A1

Not part of this code, but both may be coded when both are present.

Written on I21: Acute myocardial infarction

  • old myocardial infarction (I25.2)
  • postmyocardial infarction syndrome (I24.1)
  • subsequent type 1 myocardial infarction (I22.-)

Other codes that can never be billed with I21.A1

Their own Excludes1 notes name this code, so the conflict is not listed above.

  • I22Subsequent ST elevation (STEMI) and non-ST elevation (NSTEMI) myocardial infarction
  • I24.8Other forms of acute ischemic heart disease
  • I5ANon-ischemic myocardial injury (non-traumatic)

Risk adjustment

I21.A1 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.A1 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›type 2
  • Ischemia, ischemic›demand›resulting in myocardial infarction
  • Ischemia, ischemic›demand›with myocardial infarction
  • Infarct, infarction›myocardium, myocardial›due to›demand ischemia
  • Infarct, infarction›myocardium, myocardial›due to›ischemic imbalance
  • Infarct, infarction›myocardium, myocardial›secondary to›demand ischemia
  • Infarct, infarction›myocardium, myocardial›secondary to›ischemic imbalance
  • Infarct, infarction›myocardium, myocardial›subsequent›type 2

Code history

Unchanged in every release from FY2024 to FY2027.

Other codes under I21.A

ICD-10-CMFY2027· effective October 1, 2026

Loaded directly from the CMS/NCHS ICD-10-CM public-domain release: see data sources and our editorial policy. If this page disagrees with the CMS tabular list, this page is wrong. Reference information for professional coders; not medical or billing advice.