Is I21.1 a billable ICD-10-CM code?

No. I21.1 is a non-billable header code. Code to a higher level of specificity using one of its child codes.

Where does I21.1 sit in the tabular list?

Diseases of the circulatory system (I00-I99), in the block Ischemic heart diseases (I20-I25).

I21.1

I21.1 — ST elevation (STEMI) myocardial infarction of inferior wall

Non-billable headerICD-10-CM

I21.1 is a non-billable header ICD-10-CM code for st elevation (stemi) myocardial infarction of inferior wall. It cannot be billed on its own: choose one of the more specific child codes below.

Inclusion terms

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

Type 1 ST elevation myocardial infarction of inferior wall

Excludes2 inherited from the categories above I21.1

Also inherited, and the opposite of Excludes1: these conditions are not part of I21.1, but a patient can have both, so you may code both.

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 I21.1

These codes carry an Excludes1 note pointing at I21.1. The conflict binds both ways, but ICD-10-CM only writes it down on one side — so you would not find this by reading I21.1 alone.

I5ANon-ischemic myocardial injury (non-traumatic)

Risk adjustment

I21.1 does not map to an HCC and does not risk-adjust under CMS-HCC V28. That is normal — most ICD-10 codes do not. It still needs to be coded correctly; it just will not move a RAF score.

Code history

I21.1 has not changed since FY2024 — no addition, revision or deletion across the three most recent ICD-10-CM releases.

Code to one of these instead I21.1

2 child codes. Green means billable.

Related codes at this level

Codes that share I21. If I21.1 is not quite right, the correct code is usually one of these.

Questions about I21.1

Is I21.1 a billable ICD-10-CM code?: No. I21.1 is a non-billable header code. Code to a higher level of specificity using one of its child codes.
Where does I21.1 sit in the tabular list?: Diseases of the circulatory system (I00-I99), in the block Ischemic heart diseases (I20-I25).