What is ICD-10 code I63.131?

I63.131 is the ICD-10-CM diagnosis code for Cerebral infarction due to embolism of right carotid artery. A stroke caused by a blood clot blocking the right carotid artery in the neck, which is a major supplier of blood to the brain. I63.131 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. I63.131 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Yes. I63.131 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. I63.131 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

What is the V28 vs V24 difference for I63.131?

CMS phased in the V28 risk adjustment model over payment years 2024 (33%), 2025 (67%), and 2026 (100%), replacing V24. V28 consolidates HCC categories, removes some lower-acuity conditions, and recalibrates RAF weights across the entire model. For I63.131, V28 maps to Ischemic or Unspecified Stroke at RAF 0.289 while V24 mapped to Ischemic or Unspecified Stroke at RAF 0.262. Both models can still appear in legacy data and in payer-specific lookback periods.

What should coders know when reporting I63.131?

Confirm right-sided carotid involvement; carotid artery strokes are common and require precise laterality documentation. Distinguish between internal carotid artery (ICA) and common carotid artery (CCA) if documented, though this code applies to both. Because I63.131 maps to a payment HCC, the documentation must also satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's risk adjustment score.

I63.131 ICD-10 Code: Cerebral infarction due

ICD-10-CM Code View

HCC Buddy Code Card

Digital ICD-10 code-book layout with official code detail, always-visible risk models, Code Trumping, and Buddy coding guidance.

Code lookupI63.131Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Diseases of the circulatory system (I00-I99) / Cerebrovascular diseases (I60-I69)

I63.131

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Cerebral infarction due to embolism of right carotid artery

A stroke caused by a blood clot blocking the right carotid artery in the neck, which is a major supplier of blood to the brain.

Buddy Insight

Cerebral infarction due to embolism of the right carotid artery is a major anterior circulation stroke caused by a traveling blood clot blocking the right carotid artery.

CMS-HCC V28

Mapped

HCC 249

Ischemic or Unspecified Stroke

RAF 0.289

CMS-HCC V24

Mapped

HCC 100

Ischemic or Unspecified Stroke

RAF 0.262

ACA/HHS

Not risk-adjusted for this model/period.

RAF 0

ESRD/PACE

Mapped

HCC 100

Ischemic or Unspecified Stroke

RAF 0.0

RXHCC

Not risk-adjusted for this model/period.

RAF 0

Code Trumping

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Code Book Path

Official

I63.1Cerebral infarction due to embolism of precerebral arteries

I63.13Cerebral infarction due to embolism of carotid artery

I63.131Cerebral infarction due to embolism of right carotid artery

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for I63.131 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for I63.131 in this effective period.

Related Child Codes

Official

I63.132Cerebral infarction due to embolism of left carotid artery

I63.133Cerebral infarction due to embolism of bilateral carotid arteries

I63.139Cerebral infarction due to embolism of unspecified carotid artery

Includes

Official

ICD-10-CM does not list Includes notes for I63.131 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for I63.131 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for I63.131 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for I63.131 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for I63.131 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Imaging confirmation of acute cerebral infarction in right carotid territory

Vascular imaging confirming embolic occlusion of the right carotid artery

Documentation specifying right-sided laterality and embolic mechanism

Neurological examination with left-sided motor/sensory findings and hemispatial neglect assessment

MEAT Support

HCC Buddy guidance

Imaging confirmation of acute cerebral infarction in right carotid territory

Vascular imaging confirming embolic occlusion of the right carotid artery

Documentation specifying right-sided laterality and embolic mechanism

Neurological examination with left-sided motor/sensory findings and hemispatial neglect assessment

Audit Caution

HCC Buddy guidance

Assuming right carotid embolism without vascular imaging confirmation

Not distinguishing embolism from thrombosis when the documentation is ambiguous

Coding artery-to-artery embolism (from carotid plaque) using cardiogenic embolism concepts

Not coding the embolic source (atrial fibrillation, valvular disease) alongside the stroke

Common Mistakes

HCC Buddy guidance

I63.031 — Thrombosis of right carotid artery; in situ clot, not embolism

I63.132 — Embolism of left carotid artery; opposite laterality

I63.139 — Embolism of unspecified carotid artery; laterality unknown

I63.231 — Unspecified occlusion of right carotid artery; mechanism not identified

Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.

Is I63.131 an HCC code?

Yes. I63.131 maps to Ischemic or Unspecified Stroke under the CMS-HCC V28 risk adjustment model (and Ischemic or Unspecified Stroke under V24).

HCC Category Mapping

V28HCC 249, Ischemic or Unspecified Stroke

0.289

V24HCC 100, Ischemic or Unspecified Stroke

0.262

ESRDHCC 100, Ischemic or Unspecified Stroke

0.000

RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.

MEAT Criteria for I63.131

For I63.131to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically, it has to be re-documented and supported each calendar year.

MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
EEvaluate: test results, medication response, or physical findings reviewed by the provider
AAssess: explicit mention in the assessment or plan with acknowledgment of status
TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis

Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed I63.131 during that encounter, not just copy-forwarded from a problem list.

What This Code Means

I63.131 is the ICD-10-CM diagnosis code for cerebral infarction due to embolism of right carotid artery. A stroke caused by a blood clot blocking the right carotid artery in the neck, which is a major supplier of blood to the brain. I63.131 sits in the ICD-10-CM chapter for diseases of the circulatory system (i00-i99), within the section covering cerebrovascular diseases (i60-i69).

Under the CMS-HCC V28 risk adjustment model, I63.131 maps to Ischemic or Unspecified Stroke (HCC 249) with a community, non-dual, aged base RAF weight of 0.289. Under the older V24 model, I63.131 mapped to the same category but with a base RAF weight of 0.262, V28 recalibrated weights across the entire model. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.

Confirm right-sided carotid involvement; carotid artery strokes are common and require precise laterality documentation. Because I63.131 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.

HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for I63.131 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Confirm right-sided carotid involvement; carotid artery strokes are common and require precise laterality documentation.
•Distinguish between internal carotid artery (ICA) and common carotid artery (CCA) if documented, though this code applies to both.

Clinical Significance

Cerebral infarction due to embolism of the right carotid artery is a major anterior circulation stroke caused by a traveling blood clot blocking the right carotid artery. This mechanism frequently originates from cardiac sources such as atrial fibrillation or valvular disease. Right carotid territory infarctions typically cause left-sided weakness and neglect syndrome, and accurate coding is essential for both risk adjustment and directing secondary prevention.

Documentation Requirements

✓Imaging confirmation of acute cerebral infarction in right carotid territory
✓Vascular imaging confirming embolic occlusion of the right carotid artery
✓Documentation specifying right-sided laterality and embolic mechanism
✓Neurological examination with left-sided motor/sensory findings and hemispatial neglect assessment
✓Cardiac workup for embolic source
✓Treatment and secondary stroke prevention plan

Commonly Confused Codes

•I63.031: Thrombosis of right carotid artery; in situ clot, not embolism
•I63.132: Embolism of left carotid artery; opposite laterality
•I63.139: Embolism of unspecified carotid artery; laterality unknown
•I63.231: Unspecified occlusion of right carotid artery; mechanism not identified
•I65.21: Occlusion of right carotid without cerebral infarction; no stroke