2027 ICD-10-CM Diagnosis Code I77.74Dissection of vertebral artery
ICD-10-CM Codes›I00–I99›I70-I79›I77
- Billable — Valid for Submission
- MCC — Major Complication or Comorbidity
- Chronic Condition
I77.74 is a billable ICD-10-CM diagnosis code for dissection of vertebral artery. 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. 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 10 closely related codes. Coders also document this condition as bilateral vertebral artery dissection. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Arterial dissections.
I77.74 no longer risk-adjusts for Medicare Advantage: it mapped to HCC 107 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 107, ESRD (V21) category 107, and ESRD (V24) category 107 for payment year 2027.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
I77.74 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.
- Bilateral vertebral artery dissection
- Dissection of anterior spinal artery
- Dissection of extracranial vertebral artery
- Dissection of intracranial vertebral artery
- Dissection of left vertebral artery
- Dissection of right vertebral artery
- Dissection of vertebral artery
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to I77.74: its own notes plus those printed at I77.7, I77, and Chapter 9. A note printed at a category, block or chapter applies to every code under it.
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.
- aneurysm of vertebral artery (I72.6)
- 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.-)
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name I77.74, its category, or a range that includes it.
Excludes2 4
These codes carry an Excludes2 note naming I77.74: its condition is not part of those codes, and both may be reported when the patient has both.
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.
Clinical InformationClinical
Dissection of Vertebral Artery
a tear within the wall of a vertebral artery.
Patient EducationClinical
Aneurysms
An aneurysm is a bulge or "ballooning" in the wall of an artery. Arteries are blood vessels that carry oxygen-rich blood from the heart to other parts of the body. If an aneurysm grows large, it can burst and cause dangerous bleeding or even death.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert I77.74 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About I77.74Overview
What is the ICD-10 code for dissection of vertebral artery?
The ICD-10-CM code for dissection of vertebral artery is I77.74 (sometimes written as I7774). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is I77.74 (Other arterial dissection) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report dissection of vertebral artery on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does I77.74 group to?
When dissection of vertebral artery is the principal diagnosis on an inpatient stay, it groups to MS-DRG 301, 300, 299, with relative weights from 0.7132 to 1.5840 depending on complications. Higher weights mean higher Medicare reimbursement.
Is I77.74 a CC or MCC?
CMS lists I77.74 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 10 closely related codes in its exclusion list.
What is the ICD-9 equivalent of I77.74?
Under the General Equivalence Mappings, dissection of vertebral artery converts to ICD-9-CM 443.24 (dissect vertebral artery). The mapping is a direct match.
Does I77.74 risk-adjust for Medicare Advantage payment?
Not for Medicare Advantage. I77.74 mapped to HCC 107 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 107 (Vascular Disease with Complications), ESRD (V21) category 107 (Vascular Disease with Complications), and ESRD (V24) category 107 (Vascular Disease with Complications).
