2027 ICD-10-CM Diagnosis Code I22.8Subsequent ST elevation (STEMI) myocardial infarction of other sites
ICD-10-CM Codes›I00–I99›I20-I25›STEMI
- Billable — Valid for Submission
- MCC — Major Complication or Comorbidity
- Risk Adjusts — HCC 228
- Chronic Condition
I22.8 is a billable ICD-10-CM diagnosis code for subsequent ST elevation (STEMI) myocardial infarction of other sites. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 280 through 285. As a secondary diagnosis, it counts as a major complication or comorbidity (MCC) and places an inpatient stay in the highest severity level of its MS-DRG family. It does not count, however, when the principal diagnosis is one of 25 closely related codes. Coders also document this condition as subsequent myocardial infarction of anterior wall. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Acute myocardial infarction.
For Medicare Advantage risk adjustment, I22.8 maps to CMS-HCC Category 228 (Acute Myocardial Infarction) under the V28 model, adding a risk factor of about 0.252 for a community, non-dual, aged beneficiary in payment year 2027.
This medical diagnosis code is frequently used in Cardiology medical specialties to designate conditions such selected atherosclerosis, ischemia, and infarction.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
I22.8 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2027.
Source: CMS Payment Year 2027 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Subsequent myocardial infarction of anterior wall
- Subsequent ST segment elevation myocardial infarction
- Subsequent ST segment elevation myocardial infarction of anterior wall
- Subsequent ST segment elevation myocardial infarction of anterolateral wall
- Subsequent ST segment elevation myocardial infarction of inferolateral wall
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to I22.8: its own notes plus those printed at I22, block I20-I25, and Chapter 9. A note printed at a category, block or chapter applies to every code under it.
Includes
Further defines, or gives examples of, the content of the category.
- acute myocardial infarction occurring within four weeks (28 days) of a previous acute myocardial infarction, regardless of site
- cardiac infarction
- coronary (artery) embolism
- coronary (artery) occlusion
- coronary (artery) rupture
- coronary (artery) thrombosis
- infarction of heart, myocardium, or ventricle
- recurrent myocardial infarction
- reinfarction of myocardium
- rupture of heart, myocardium, or ventricle
- subsequent type 1 myocardial infarction
Applicable To
Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.
- Subsequent acute transmural myocardial infarction of other sites
- Subsequent apical-lateral transmural (Q wave) myocardial infarction (acute)
- Subsequent basal-lateral transmural (Q wave) myocardial infarction (acute)
- Subsequent high lateral transmural (Q wave) myocardial infarction (acute)
- Subsequent transmural (Q wave) myocardial infarction (acute)(of) lateral (wall) NOS
- Subsequent posterior (true) transmural (Q wave) myocardial infarction (acute)
- Subsequent posterobasal transmural (Q wave) myocardial infarction (acute)
- Subsequent posterolateral transmural (Q wave) myocardial infarction (acute)
- Subsequent posteroseptal transmural (Q wave) myocardial infarction (acute)
- Subsequent septal NOS transmural (Q wave) myocardial infarction (acute)
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
- certain conditions originating in the perinatal period (P04-P96)
- certain infectious and parasitic diseases (A00-B99)
- complications of pregnancy, childbirth and the puerperium (O00-O9A)
- congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
- endocrine, nutritional and metabolic diseases (E00-E88)
- injury, poisoning and certain other consequences of external causes (S00-T88)
- neoplasms (C00-D49)
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
- systemic connective tissue disorders (M30-M36)
- transient cerebral ischemic attacks and related syndromes (G45.-)
Use Additional Code
Add a second code, after this one, to fully describe the condition.
- 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
A second code may be needed to fully describe the condition; the note gives no sequencing direction.
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name I22.8, its category, or a range that includes it.
Excludes1 1
These codes carry an Excludes1 note naming I22.8: they are not reported together with it, unless the two conditions are unrelated.
Excludes2 3
These codes carry an Excludes2 note naming I22.8: its condition is not part of those codes, and both may be reported when the patient has both.
Code First 1
These codes say to code first a condition named in the note, and I22.8 is one of the conditions named.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Heart Attack
A heart attack, also called a myocardial infarction, is a type of heart disease. It happens when blood flow to the heart suddenly becomes blocked. Without the blood coming in, the heart can't get oxygen. If not treated quickly, the heart muscle begins to die.
The full article covers:
- What is a heart attack?
- What heart attack risk factors can be changed?
- What heart attack risk factors can't be changed?
- What causes a heart attack?
- What are the symptoms of a heart attack?
- How is a heart attack diagnosed?
- What is the treatment for a heart attack?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert I22.8 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About I22.8Overview
What is the ICD-10 code for subsequent ST elevation (STEMI) myocardial infarction of other sites?
The ICD-10-CM code for subsequent ST elevation (STEMI) myocardial infarction of other sites is I22.8 (sometimes written as I228). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is I22.8 a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report subsequent ST elevation (STEMI) myocardial infarction of other sites on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does I22.8 group to?
When subsequent ST elevation (STEMI) myocardial infarction of other sites is the principal diagnosis on an inpatient stay, it groups to MS-DRG 282, 285, 281, 280, 283, 284, with relative weights from 0.5197 to 1.9615 depending on complications. Higher weights mean higher Medicare reimbursement.
Is I22.8 a CC or MCC?
CMS lists I22.8 as an MCC (major complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it places the inpatient stay in the highest-weighted DRG of its severity family. It does not count when the principal diagnosis is one of the 25 closely related codes in its exclusion list.
Can I22.8 be reported with I21.A1?
Not as a rule. The Excludes1 note at I22, which applies to I22.8, lists "subsequent myocardial infarction, type 2 (I21.A1)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).
What HCC is I22.8?
I22.8 (subsequent ST elevation (STEMI) myocardial infarction of other sites) maps to CMS-HCC Category 228 (Acute Myocardial Infarction), commonly written as HCC 228, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2027. It mapped to HCC 86 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. In the Part D prescription drug model it maps to RxHCC 188.
Does I22.8 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, I22.8 adds a risk adjustment factor of about 0.252 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.252 to 0.517 depending on the payment segment). HCC 228 sits at the top of its hierarchy, so no other condition category supersedes it. See the full factor table on the HCC 228 category page.
