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    v1.0.28
    OpenPayerBilling CodesIschemic heart diseasesICD-10-CM i21-acute-myocardial-infarction
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    ICD-10-CM Code For Acute Myocardial Infarction: Group Overview

    The International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) code group I21 includes diagnoses of acute myocardial infarction, specifying types such as ST-elevation and non-ST-elevation infarctions and indicating location and timing of the infarct. These ICD-10-CM diagnosis codes are used to document acute ischemic injury to the heart muscle, capturing clinical severity, infarct location, and treatment context relevant to acute coronary syndromes. Accurate coding within the ICD-10-CM I21 group supports appropriate claim adjudication and complete clinical documentation to reflect resource use and care intensity.

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    ICD-10-CM I21: Acute Myocardial Infarction Overview

    The ICD-10-CM I21 group represents acute myocardial infarction diagnoses involving acute ischemic necrosis of heart muscle due to coronary artery occlusion or reduced blood flow. These codes target the cardiovascular system and specify infarction type, location, and timing to reflect clinical severity. Accurate coding matters for proper clinical documentation, claim processing, and capturing the intensity of care required.

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    When to Use

    Use a code from this group when a clinician documents an acute myocardial infarction event with sufficient specificity about timing and infarct location. Select codes reflecting whether the infarction is ST-elevation or non-ST-elevation and whether it is an initial or subsequent episode as documented in the clinical record.

    ICD-10-CM Codes

    13 rows

    ICD-10-CM CodeDescription
    I21.01ST elevation (STEMI) myocardial infarction involving left main coronary artery
    I21.02ST elevation (STEMI) myocardial infarction involving left anterior descending coronary artery
    I21.09ST elevation (STEMI) myocardial infarction involving other coronary artery of anterior wall
    I21.11ST elevation (STEMI) myocardial infarction involving right coronary artery
    I21.19ST elevation (STEMI) myocardial infarction involving other coronary artery of inferior wall
    I21.21ST elevation (STEMI) myocardial infarction involving left circumflex coronary artery
    I21.29ST elevation (STEMI) myocardial infarction involving other sites
    I21.3ST elevation (STEMI) myocardial infarction of unspecified site
    I21.4Non-ST elevation (NSTEMI) myocardial infarction
    I21.9Acute myocardial infarction, unspecified
    I21.A1Myocardial infarction type 2
    I21.A9Other myocardial infarction type
    I21.BMyocardial infarction with coronary microvascular dysfunction

    DRG Codes

    6 rows

    DRG CodeDescription
    280Acute Myocardial Infarction, Discharged Alive with MCC
    281Acute Myocardial Infarction, Discharged Alive with CC
    282Acute Myocardial Infarction, Discharged Alive without CC/MCC
    283Acute Myocardial Infarction, Expired with MCC
    284Acute Myocardial Infarction, Expired with CC
    285Acute Myocardial Infarction, Expired without CC/MCC

    Typical Clinical Scenarios

    • An adult presents to the emergency department with sudden central chest pressure radiating to the left arm, diaphoresis, nausea, and ST-elevation in the anterior precordial leads on ECG; emergent percutaneous coronary intervention is performed and troponin is markedly elevated. A diagnosis from this group is assigned for an acute transmural infarction of the anterior wall confirmed by ECG and biomarkers. Typical codes: I21.01, I21.02
    • An older patient arrives with new-onset substernal chest pain several days after an episode of prolonged chest discomfort; ECG shows ST elevation in inferior leads and serial troponins are rising. This represents an acute ST-elevation myocardial infarction of the inferior wall requiring hospital admission and cardiac monitoring, so an acute MI code from this group is used. Typical codes: I21.11, I21.19
    • A middle-aged patient hospitalized for acute decompensated heart failure is found to have had a recent silent myocardial infarction on troponin assay and imaging without classic chest pain; documentation indicates a recent MI as a complicating condition contributing to the current admission. A code from this group denoting a recent or non–ST-elevation infarction is assigned to capture the acute ischemic event complicating care. Typical codes: I21.4, I21.9

    Related Codes

    I20-ANGINA-PECTORIS

    ICD-10-CM Code For Angina Pectoris: Group Overview

    I22-SUBSEQUENT-MYOCARDIAL-INFARCTION

    ICD-10-CM Code For Subsequent ST Elevation (STEMI) And Non-ST Elevation (NSTEMI) Myocardial Infarction: Group Overview

    I23-CERTAIN-CURRENT-COMPLICATIONS-FOLLOWING-MYOCARDIAL-INFARCTION

    ICD-10-CM Code For Certain Current Complications Following STEMI And NSTEMI: Group Overview

    I24-OTHER-ACUTE-ISCHEMIC-HEART-DISEASES

    ICD-10-CM Code For Other Acute Ischemic Heart Diseases: Group Overview

    I25-CHRONIC-ISCHEMIC-HEART-DISEASE

    ICD-10-CM Code For Chronic Ischemic Heart Disease: Group Overview

    Frequently Asked Questions

    References

    1. 1.CPT® Codes and Descriptions. AAPC. Retrieved Aug 11, 2026.Maintains the CPT code set's official descriptions and guidelines, licensed from the American Medical Association, used as the definitional source for CPT codes on this page.
    2. 2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's quarterly release of HCPCS Level II codes and short/long descriptors, the source for HCPCS code definitions and update history.
    3. 3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's complete ICD-10-CM diagnosis code list, used to cross-reference diagnosis codes associated with this procedure or service.
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