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ICD-10 Code I22.9: Subsequent ST elevation (STEMI) myocardial infarction of unspecified site

I22.9 is a billable ICD-10 diagnosis code used to classify Subsequent ST elevation (STEMI) myocardial infarction of unspecified site in medical records and claims. You may see this code in hospital records, discharge summaries, insurance claims, encounter documentation, referrals, or other healthcare billing and coding records. ICD-10 codes are diagnosis classification codes used in healthcare records, reporting, coding workflows, and billing support. This code sits within the broader ICD-10 area for Diseases of the circulatory system (I00-I99).

What is this code?

ICD-10 codes are diagnosis classification codes used in healthcare records, reporting, coding workflows, and billing support. This code sits within the broader ICD-10 area for Diseases of the circulatory system (I00-I99).

đź“‹Clinical overview

This ICD-10 code is commonly used when documentation describes a subsequent myocardial infarction after a recent prior infarction. The most accurate code depends on whether the later infarction is STEMI versus NSTEMI and whether the site is anterior, inferior, other, or unspecified.

When is it used?

  • May be used when a clinician documents subsequent st elevation (stemi) myocardial infarction of unspecified site in a patient's medical record.
  • May appear in hospital records, claims, referrals, and clinical documentation.
  • This code can be used as a clinically usable diagnosis entry in standardized coding workflows.

What it does not mean

  • A code alone does not explain severity, treatment plan, or outcome.
  • A medical code should not be treated as a substitute for a doctor's diagnosis or advice.

đź©şClinical context

When commonly used
  • Inpatient, cardiology, emergency, and utilization-review workflows where the chart documents a subsequent myocardial infarction rather than the first acute event.
  • Coding workflows where the record identifies subsequent STEMI versus subsequent NSTEMI and clarifies infarct territory, changing final code specificity.
Common management context
  • Evaluation often includes recurrent-ischemia symptom review, ECG interpretation, troponin testing, coronary-imaging or catheterization context, and acute cardiology management planning.
  • Documentation usually becomes more specific when the chart identifies subsequent STEMI versus NSTEMI and names anterior-wall, inferior-wall, other-site, or unspecified-site involvement.
  • Specialist context already linked on this page includes Cardiologist, General Physician.

🔍Key distinctions

Important notes
  • This ICD-10 family captures a subsequent myocardial infarction rather than the initial acute myocardial infarction itself.
  • Subsequent STEMI versus NSTEMI pattern and infarct territory are what drive final code specificity inside this family.
  • Subsequent STEMI is coded separately from subsequent NSTEMI within this follow-on myocardial-infarction family.
  • This title preserves unspecified subsequent-infarction site detail; if the chart identifies the infarct territory more clearly, a more specific subsequent-MI code may be used.
  • Documentation that describes a subsequent myocardial infarction is coded differently from the initial acute myocardial infarction, chronic ischemic heart disease, or a remote healed prior infarction.
Related codes to consider
I22.0Subsequent ST elevation (STEMI) myocardial infarction of anterior wall
Related subsequent-myocardial-infarction ICD-10 code; documentation often becomes more specific when the chart identifies subsequent STEMI versus NSTEMI, infarct territory, or distinguishes the follow-on infarction from the initial acute event.
I22.1Subsequent ST elevation (STEMI) myocardial infarction of inferior wall
Related subsequent-myocardial-infarction ICD-10 code; documentation often becomes more specific when the chart identifies subsequent STEMI versus NSTEMI, infarct territory, or distinguishes the follow-on infarction from the initial acute event.
I22.2Subsequent non-ST elevation (NSTEMI) myocardial infarction
Related subsequent-myocardial-infarction ICD-10 code; documentation often becomes more specific when the chart identifies subsequent STEMI versus NSTEMI, infarct territory, or distinguishes the follow-on infarction from the initial acute event.
I22.8Subsequent ST elevation (STEMI) myocardial infarction of other sites
Related subsequent-myocardial-infarction ICD-10 code; documentation often becomes more specific when the chart identifies subsequent STEMI versus NSTEMI, infarct territory, or distinguishes the follow-on infarction from the initial acute event.

Code hierarchy

chapter
9Diseases of the circulatory system (I00-I99)
block
I20-I25Ischemic heart diseases
category
I22Subsequent ST elevation (STEMI) and non-ST elevation (NSTEMI) myocardial infarction
currentI22

Official coding notes

Inclusion terms
  • Subsequent acute myocardial infarction of unspecified site
  • Subsequent myocardial infarction (acute) NOS

Where you may see this code

You may see this code in hospital records, discharge summaries, insurance claims, encounter documentation, referrals, or other healthcare billing and coding records.

Related specialists

CardiologistGeneral Physician

Coverage-related procedures and services

CPT 0349Uhigh
DRUG METABOLISM OR PROCESSING (MULTIPLE CONDITIONS), WHOLE BLOOD OR BUCCAL SPECIMEN, DNA ANALYSIS, 27 GENE REPORT, WITH VARIANT ANALYSIS, INCLUDING REPORTED PHENOTYPES AND IMPACTED GENE-DRUG INTERACTIONS
Source: CMS coverage guidance
CPT 83880high
NATRIURETIC PEPTIDE
Source: CMS coverage guidance
CPT 81479high
UNLISTED MOLECULAR PATHOLOGY PROCEDURE
Source: CMS coverage guidance
CPT 76376high
3D RENDERING WITH INTERPRETATION AND REPORTING OF COMPUTED TOMOGRAPHY, MAGNETIC RESONANCE IMAGING, ULTRASOUND, OR OTHER TOMOGRAPHIC MODALITY WITH IMAGE POSTPROCESSING UNDER CONCURRENT SUPERVISION; NOT REQUIRING IMAGE POSTPROCESSING ON AN INDEPENDENT WORKSTATION
Source: CMS coverage guidance
CPT 76377high
3D RENDERING WITH INTERPRETATION AND REPORTING OF COMPUTED TOMOGRAPHY, MAGNETIC RESONANCE IMAGING, ULTRASOUND, OR OTHER TOMOGRAPHIC MODALITY WITH IMAGE POSTPROCESSING UNDER CONCURRENT SUPERVISION; REQUIRING IMAGE POSTPROCESSING ON AN INDEPENDENT WORKSTATION
Source: CMS coverage guidance
CPT 93325high
DOPPLER ECHOCARDIOGRAPHY COLOR FLOW VELOCITY MAPPING (LIST SEPARATELY IN ADDITION TO CODES FOR ECHOCARDIOGRAPHY)
Source: CMS coverage guidance

Coding guidelines

Compatibility

Legacy and official ICD code match exactly.
Legacy codes
I22.9

Common synonyms

Subsequent ST elevation (STEMI) myocardial infarction of unspecified siteSubsequent ST elevation (STEMI) myocardial infarction of siteSubsequent ST elevationSubsequent ST elevation STEMI myocardial infarction of unspecified site

Frequently asked questions

Code details

CodeI22.9
SystemICD10
Display nameSubsequent ST elevation (STEMI) myocardial infarction of unspecified site
ChapterDiseases of the circulatory system (I00-I99)
BlockIschemic heart diseases

Flags

BillableYes
Valid clinical useYes

Source

SourceICD-10
Version2026-annual
Releaseannual
Year2026

Index terms

Matched terms
Infarct, infarctionInfarct, infarctionInfarct, infarctionInfarct, infarctionInfarct, infarction
See also
Infarction, myocardial, subsequent, by site, or by ST elevation or non-ST elevation

About this content

This page is prepared by HealthAssure's clinical team using official coding standards from ICD-10. AI tools assist with drafting explanations, which are then reviewed and verified by healthcare professionals for accuracy. This content is for informational purposes and does not replace professional medical advice. Meet our team.