ICD-10 I66
Non-Billable HeaderOcclusion and stenosis of cerebral arteries, not resulting in cerebral infarction
About ICD-10-CM I66
ICD-10-CM code I66 represents Occlusion and stenosis of cerebral arteries, not resulting in cerebral infarction. This is a non-billable header code in the Circulatory System chapter (block I66). The 2026 edition of ICD-10-CM I66 became effective on October 1, 2025. Non-billable codes cannot be used as a primary or secondary diagnosis on a claim, use a more specific child code instead.
Type 1 Excludes
Pure excludes, these codes can never be coded together with I66. The conditions are mutually exclusive (e.g., congenital vs acquired forms).
- Occlusion and stenosis of cerebral artery causing cerebral infarction (I63.3-I63.5)
Includes
- embolism of cerebral artery
- narrowing of cerebral artery
- obstruction (complete) (partial) of cerebral artery
- thrombosis of cerebral artery
Medicare LCD Coverage for I66
Local Coverage Determinations (LCDs) from CMS MACs that list I66 as a covered diagnosis.
This doesn't mean the code isn't covered, it means no MAC has issued a Local Coverage Determination naming this specific code. Coverage may still apply under National Coverage Determinations or general medical-necessity rules.
Commercial Payer Coverage
Coverage policies from major commercial payers referencing I66.
Our payer policy database covers Aetna, Cigna, Anthem, BCBS, Humana, and Medicare Advantage plans, but I66 doesn't currently appear in any indexed policy. The code may still be covered under standard plan benefits.
CPT Codes Commonly Billed with I66
Procedures frequently paired with this diagnosis based on PayerReady's Dx↔Px linkage data.
We don't have CPT pairings indexed for this specific code yet. Use the CPT search above to find common procedures, or check your payer's published medical policy for code-specific guidance.
Codes Adjacent To I66
Other codes in section I60-I69 (Cerebrovascular diseases).
ICD-10 I66, Billing FAQ
Is ICD-10 code I66 billable? +
No, I66 is a non-billable header code. Use a more specific child code from block I66 when submitting claims.
What codes are Type 1 Excludes for I66? +
Type 1 Excludes (never code together with I66): Occlusion and stenosis of cerebral artery causing cerebral infarction (I63.3-I63.5)
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Reviewed by the PayerReady Medical Coding Team
Verified against the CMS 2026 code set on May 31, 2026.
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