2027 ICD-10-CM Diagnosis Code I79.1Aortitis in diseases classified elsewhere
ICD-10-CM Codes›I00–I99›I70-I79›I79
- Billable — Valid for Submission
- Not Chronic
I79.1 is a billable ICD-10-CM diagnosis code for aortitis in diseases classified elsewhere. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 299 through 301. The code is a manifestation code that cannot be reported as the principal diagnosis. Coders also document this condition as immunoglobulin G4 related aortitis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified and unspecified circulatory disease.
I79.1 no longer risk-adjusts for Medicare Advantage: it mapped to HCC 108 under the retired CMS-HCC V24 model through payment year 2025 but maps to no category in the live V28 model. It still risk-adjusts in the PACE (CMS-HCC V22) category 108, ESRD (V21) category 108, and ESRD (V24) category 108 for payment year 2027.
Code Identity
Code Classification
Code EditsBilling
Medicare Code Editor checks that affect claim validity for I79.1.
Medicare Risk Adjustment (HCC)Billing
I79.1 no longer risk-adjusts for Medicare Advantage: it maps to no payment category in the live CMS-HCC V28 model, although it still risk-adjusts in the other CMS models shown below.
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.
- Immunoglobulin G4 related aortitis
- Immunoglobulin G4 related periaortitis
- Secondary aortitis
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to I79.1: its own notes plus those printed at 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.
- syphilitic aortitis (A52.02)
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 First
The underlying condition named in the note is sequenced before this code.
- underlying disease
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Vascular Diseases
Your vascular system is your body's network of blood vessels. It includes your:
The full article covers:
- What are vascular diseases?
- What causes vascular diseases?
- Who is at risk for vascular diseases?
- What are the symptoms of vascular diseases?
- How are vascular diseases diagnosed?
- How are vascular diseases treated?
- Can vascular diseases be prevented?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert I79.1 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About I79.1Overview
What is the ICD-10 code for aortitis in diseases classified elsewhere?
The ICD-10-CM code for aortitis in diseases classified elsewhere is I79.1 (sometimes written as I791). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is I79.1 a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report aortitis in diseases classified elsewhere on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does I79.1 group to?
On inpatient claims, aortitis in diseases classified elsewhere maps to MS-DRG 301, 300, 299, with relative weights from 0.7132 to 1.5840 depending on complications. Higher weights mean higher Medicare reimbursement.
Can I79.1 be a principal diagnosis?
No. This is a manifestation code: aortitis in diseases classified elsewhere describes the manifestation of an underlying disease rather than the disease itself, so the underlying condition is sequenced first.
Can I79.1 be reported with A52.02?
Not as a rule. The Excludes1 note on I79.1 lists "syphilitic aortitis (A52.02)". 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).
Does I79.1 risk-adjust for Medicare Advantage payment?
Not for Medicare Advantage. I79.1 mapped to HCC 108 in the retired CMS-HCC V24 model, which last determined payment in 2025, but it maps to no category in the live V28 model; see all codes that no longer risk-adjust. It still risk-adjusts in the PACE (CMS-HCC V22) category 108 (Vascular Disease), ESRD (V21) category 108 (Vascular Disease), and ESRD (V24) category 108 (Vascular Disease).
