I21.1 is the authoritative medical code for ST elevation STEMI myocardial infarction of inferior wall. This classification is used in medical billing and clinical recording to specify the clinical criteria for st elevation stemi myocardial infarction of inferior wall (ICD-10-CM I21.1), ensuring healthcare documentation aligns with 2026 federal coding standards.
Billing Status: NO. This is a clinician non-billable / parent hierarchy grouping in the ICD-10-CM system.
Official Registry Overview & Definition
ST elevation STEMI myocardial infarction of inferior wall is a non-billable ICD-10-CM category code I21.1. A more specific billable subcode must be selected for claims submission. Includes: cardiac infarction; coronary artery embolism; coronary artery occlusion; coronary artery rupture; coronary artery thrombosis; infarction of heart, myocardium, or ventricle; myocardial infarction specified as acute or with a stated duration of 4 weeks (28 days) or less from onset. Inclusion terms: Type 1 ST elevation myocardial infarction of inferior wall. Excludes2 (not included here): old myocardial infarction I25.2; postmyocardial infarction syndrome I24.1; subsequent type 1 myocardial infarction I22.-. Use additional code: code, if applicable, to identify:; exposure to environmental tobacco smoke Z77.22; history of tobacco dependence Z87.891; occupational exposure to environmental tobacco smoke Z57.31; status post administration of tPA rtPA in a different facility within the last 24 hours prior to admission to current facility Z92.82; tobacco dependence F17.-; tobacco use Z72.0. Code also: the presence of hypertension I10-I1A.
Official Tabular Instructional Notes
Sequencing, inclusion, and exclusion notes published for I21.1 in the official ICD-10-CM tabular list.
Includes
Conditions the official ICD-10-CM tabular list includes under this code.
- cardiac infarction
- coronary artery embolism
- coronary artery occlusion
- coronary artery rupture
- coronary artery thrombosis
- infarction of heart, myocardium, or ventricle
- myocardial infarction specified as acute or with a stated duration of 4 weeks (28 days) or less from onset
Inclusion Terms
Alternative terms the tabular list files under this code.
- Type 1 ST elevation myocardial infarction of inferior wall
Excludes2 — Not Included Here
Conditions not covered by this code, but which may be reported alongside it when both are present.
- old myocardial infarction I25.2
- postmyocardial infarction syndrome I24.1
- subsequent type 1 myocardial infarction I22.-
Code Also
Additional codes that may be required to fully describe the encounter.
- the presence of hypertension I10-I1A
Use Additional Code
Supplementary codes the tabular list directs you to add.
- code, if applicable, to identify:
- exposure to environmental tobacco smoke Z77.22
- history of tobacco dependence Z87.891
- occupational exposure to environmental tobacco smoke Z57.31
- status post administration of tPA rtPA in a different facility within the last 24 hours prior to admission to current facility Z92.82
- tobacco dependence F17.-
- tobacco use Z72.0
Frequently Asked Questions (FAQ) & Clinical Guidance
Can I21.1 be billed directly?
No. I21.1 (ST elevation STEMI myocardial infarction of inferior wall) is a non-billable ICD-10-CM category code. A more specific billable subcode must be selected based on clinical documentation.
Can I21.1 be reported alongside related conditions?
Per official ICD-10-CM Excludes2 instructions, I21.1 and the following are not considered part of each other and may both be reported when both conditions are present: old myocardial infarction (I25.2); postmyocardial infarction syndrome (I24.1); subsequent type 1 myocardial infarction (I22.-).
Is an additional code needed with I21.1?
Use additional code(s) to specify: code, if applicable, to identify:; exposure to environmental tobacco smoke (Z77.22); history of tobacco dependence (Z87.891); occupational exposure to environmental tobacco smoke (Z57.31).
What conditions are included under I21.1?
ST elevation STEMI myocardial infarction of inferior wall includes: Type 1 ST elevation myocardial infarction of inferior wall.
Nearest Codes in This Family
Official ICD-10-CM classifications closest to I21.1 in its code family, with their registry titles.
- I21.11 — ST elevation (STEMI) myocardial infarction involving right coronary artery
- I21.19 — ST elevation (STEMI) myocardial infarction involving other coronary artery of inferior wall