What is ICD-10 code I63.513?

I63.513 is the ICD-10-CM diagnosis code for Cerebral infarction due to unspecified occlusion or stenosis of bilateral middle cerebral arteries. A stroke caused by a narrowing or blockage affecting both the right and left middle cerebral arteries simultaneously. I63.513 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. I63.513 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. I63.513 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. I63.513 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 I63.513?

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 I63.513, 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 I63.513?

Ensure documentation clearly indicates bilateral involvement of both middle cerebral arteries This is a rare presentation; verify documentation carefully before coding Because I63.513 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.

I63.513 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 lookupI63.513Effective periodFY2026 Apr Update (Apr 1-Sep 30)

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

I63.513

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

Cerebral infarction due to unspecified occlusion or stenosis of bilateral middle cerebral arteries

A stroke caused by a narrowing or blockage affecting both the right and left middle cerebral arteries simultaneously.

Buddy Insight

This code identifies an acute ischemic stroke due to occlusion or stenosis of the bilateral middle cerebral artery where the specific mechanism (thrombosis versus embolism) is not documented.

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

I63.5Cerebral infarction due to unspecified occlusion or stenosis of cerebral arteries

I63.51Cerebral infarction due to unspecified occlusion or stenosis of middle cerebral artery

I63.513Cerebral infarction due to unspecified occlusion or stenosis of bilateral middle cerebral arteries

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for I63.513 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for I63.513 in this effective period.

Related Child Codes

Official

I63.511Cerebral infarction due to unspecified occlusion or stenosis of right middle cerebral artery

I63.512Cerebral infarction due to unspecified occlusion or stenosis of left middle cerebral artery

I63.519Cerebral infarction due to unspecified occlusion or stenosis of unspecified middle cerebral artery

Includes

Official

ICD-10-CM does not list Includes notes for I63.513 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for I63.513 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for I63.513 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for I63.513 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for I63.513 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Provider documentation of acute cerebral infarction (stroke) as a confirmed diagnosis, not rule-out or suspected

Identification of the affected artery as the middle cerebral artery

Documentation of laterality (bilateral) supported by clinical findings and/or imaging

If the mechanism (thrombosis vs. embolism) can be determined from imaging or clinical workup, a more specific code should be assigned

MEAT Support

HCC Buddy guidance

Provider documentation of acute cerebral infarction (stroke) as a confirmed diagnosis, not rule-out or suspected

Identification of the affected artery as the middle cerebral artery

Documentation of laterality (bilateral) supported by clinical findings and/or imaging

If the mechanism (thrombosis vs. embolism) can be determined from imaging or clinical workup, a more specific code should be assigned

Audit Caution

HCC Buddy guidance

Using this unspecified occlusion/stenosis code when the medical record clearly documents thrombosis or embolism as the mechanism — always code to the highest specificity supported by documentation

Assigning an acute cerebral infarction code for a history of stroke or residual deficits from a prior stroke — use I69.3xx sequelae codes for follow-up encounters after the acute phase

Failing to capture laterality when it is documented — avoid defaulting to the unspecified laterality code when the provider has documented a specific side

Coding a transient ischemic attack as a cerebral infarction — a transient ischemic attack resolves within 24 hours with no infarction on imaging and uses G45 codes instead

Common Mistakes

HCC Buddy guidance

I63.313 — Cerebral infarction due to thrombosis of bilateral middle cerebral arteries; use when thrombosis is the documented mechanism

I63.413 — Cerebral infarction due to embolism of bilateral middle cerebral arteries; use when embolism is the documented mechanism

I69.3xx — Sequelae of cerebral infarction; use for residual deficits from a prior stroke during follow-up visits, not during the acute event

G45.9 — Transient cerebral ischemic attack, unspecified; use when symptoms resolve completely within 24 hours with no evidence of infarction on imaging

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 I63.513 an HCC code?

Yes. I63.513 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 I63.513

For I63.513to 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 I63.513 during that encounter, not just copy-forwarded from a problem list.

What This Code Means

I63.513 is the ICD-10-CM diagnosis code for cerebral infarction due to unspecified occlusion or stenosis of bilateral middle cerebral arteries. A stroke caused by a narrowing or blockage affecting both the right and left middle cerebral arteries simultaneously. I63.513 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, I63.513 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, I63.513 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.

Ensure documentation clearly indicates bilateral involvement of both middle cerebral arteries. Because I63.513 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 I63.513 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Ensure documentation clearly indicates bilateral involvement of both middle cerebral arteries
•This is a rare presentation; verify documentation carefully before coding

Clinical Significance

This code identifies an acute ischemic stroke due to occlusion or stenosis of the bilateral middle cerebral artery where the specific mechanism (thrombosis versus embolism) is not documented. The middle cerebral artery supplies the lateral cerebral cortex including motor and sensory areas for the face and upper extremity, as well as language areas (Broca's and Wernicke's) in the dominant hemisphere. Accurate coding of the mechanism, artery, and laterality is critical for risk adjustment and tracking stroke subtypes for quality measures and secondary prevention strategies.

Documentation Requirements

✓Provider documentation of acute cerebral infarction (stroke) as a confirmed diagnosis, not rule-out or suspected
✓Identification of the affected artery as the middle cerebral artery
✓Documentation of laterality (bilateral) supported by clinical findings and/or imaging
✓If the mechanism (thrombosis vs. embolism) can be determined from imaging or clinical workup, a more specific code should be assigned
✓Neurological examination findings consistent with the identified vascular territory (e.g., contralateral hemiparesis (face and arm worse than leg), hemisensory loss, and aphasia (dominant hemisphere) or neglect (non-dominant hemisphere))
✓Brain imaging (computed tomography or magnetic resonance imaging) confirming acute infarction
✓Timing of symptom onset to confirm acute presentation
✓Documentation of stroke severity (National Institutes of Health Stroke Scale score preferred)
✓Treatment administered (thrombolytics, thrombectomy, antiplatelet therapy, anticoagulation)

Commonly Confused Codes

•I63.313: Cerebral infarction due to thrombosis of bilateral middle cerebral arteries; use when thrombosis is the documented mechanism
•I63.413: Cerebral infarction due to embolism of bilateral middle cerebral arteries; use when embolism is the documented mechanism
•I69.3xx: Sequelae of cerebral infarction; use for residual deficits from a prior stroke during follow-up visits, not during the acute event
•G45.9: Transient cerebral ischemic attack, unspecified; use when symptoms resolve completely within 24 hours with no evidence of infarction on imaging