Is I21.3 a billable ICD-10 code?

Yes. I21.3 (ST elevation (STEMI) myocardial infarction of unspecified site) is billable and can be used for insurance claims. Always verify payer-specific requirements.

I21.3 ✓ Billable

ST elevation (STEMI) myocardial infarction of unspecified site

Q: What is ICD-10 code I21.3?

ICD-10-CM code I21.3 stands for "ST elevation (STEMI) myocardial infarction of unspecified site". It is a billable code in the Diseases of the Circulatory System chapter, effective FY2026 (Oct 1, 2025 – Sep 30, 2026).

ICD-10-CM · FY2026 · Diseases of the Circulatory System

Code

I21.3

System

ICD-10-CM

Billable

Yes — valid for submission

Effective

FY2026

Chapter

Diseases of the Circulatory System

Source

CMS / CDC NCHS

⚠ Verify before billing. Confirm against the current CMS/NCHS ICD-10-CM files and your payer's rules before claims submission.

Frequently asked questions

What is ICD-10 code I21.3?

ICD-10-CM code I21.3 represents ST elevation (STEMI) myocardial infarction of unspecified site. It is a billable diagnosis code in the Diseases of the Circulatory System chapter, effective October 1, 2025 – September 30, 2026.

Is I21.3 billable?

Yes. I21.3 is a valid billable ICD-10-CM code for insurance claims and clinical documentation.

What chapter is I21.3 in?

I21.3 belongs to the Diseases of the Circulatory System chapter (I00–I99) of ICD-10-CM.

Related codes in the I21 category

I21 Acute myocardial infarction Non-billable I21.0 ST elevation (STEMI) myocardial infarction of anterior wall Non-billable I21.1 ST elevation (STEMI) myocardial infarction of inferior wall Non-billable I21.2 ST elevation (STEMI) myocardial infarction of other sites Non-billable I21.4 Non-ST elevation (NSTEMI) myocardial infarction Billable I21.9 Acute myocardial infarction, unspecified Billable I21.A Other type of myocardial infarction Non-billable I21.B Myocardial infarction with coronary microvascular dysfunction Billable

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