2027 ICD-10-CM Diagnosis Code I24.9Acute ischemic heart disease, unspecified
ICD-10-CM Codes›I00–I99›I20-I25›I24
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Risk Adjusts — HCC 229
- Chronic Condition
I24.9 is a billable ICD-10-CM diagnosis code for acute ischemic heart disease, unspecified. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 311. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 48 closely related codes. Coders also document this condition as acute coronary syndrome. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Coronary atherosclerosis and other heart disease.
For Medicare Advantage risk adjustment, I24.9 maps to CMS-HCC Category 229 (Unstable Angina and Other Acute Ischemic Heart Disease) under the V28 model, adding a risk factor of about 0.240 for a community, non-dual, aged beneficiary in payment year 2027.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
I24.9 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.
- Acute coronary syndrome
- Acute ischemic heart disease
- Acute myocardial ischemia
- Erythrocytosis due to cardiovascular disease
- Erythrocytosis due to tissue hypoxemia
- Polycythemia due to cyanotic heart disease
- Subacute ischemic heart disease
- Transient myocardial ischemia
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to I24.9: its own notes plus those printed at I24, block I20-I25, and Chapter 9. A note printed at a category, block or chapter applies to every code under it.
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
- ischemic heart disease (chronic) NOS (I25.9)
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.-)
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 I24.9, its category, or a range that includes it.
Excludes2 3
These codes carry an Excludes2 note naming I24.9: its condition is not part of those codes, and both may be reported when the patient has both.
Index to Diseases and InjuriesGuidance
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Coronary Artery Disease
Coronary artery disease (CAD) is the most common type of heart disease in the United States and a leading cause of death for both men and women.
The full article covers:
- What is coronary artery disease?
- What causes coronary artery disease?
- What are the types of coronary artery disease?
- Who is more likely to have coronary artery disease?
- What are symptoms of coronary artery disease?
- What other problems does coronary artery disease cause?
- How is coronary artery disease diagnosed?
- What are the treatments for coronary artery disease?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert I24.9 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About I24.9Overview
What is the ICD-10 code for acute ischemic heart disease, unspecified?
The ICD-10-CM code for acute ischemic heart disease, unspecified is I24.9 (sometimes written as I249). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is I24.9 (Other acute ischemic heart diseases) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report acute ischemic heart disease, unspecified on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does I24.9 group to?
When acute ischemic heart disease, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 311 (angina Pectoris), which carries a relative weight of 0.6681. Higher weights mean higher Medicare reimbursement.
Is I24.9 a CC or MCC?
CMS lists I24.9 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 48 closely related codes in its exclusion list.
Can I24.9 be reported with I25.9?
Not as a rule. The Excludes1 note on I24.9 lists "ischemic heart disease (chronic) NOS (I25.9)". 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 I24.9?
I24.9 (acute ischemic heart disease, unspecified) maps to CMS-HCC Category 229 (Unstable Angina and Other Acute Ischemic Heart Disease), commonly written as HCC 229, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2027. It mapped to HCC 87 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 I24.9 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, I24.9 adds a risk adjustment factor of about 0.240 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.240 to 0.458 depending on the payment segment). A more severe related category (HCC 228) supersedes it when both are reported. See the full factor table on the HCC 229 category page.
