I66.12
BillableOcclusion and stenosis of left anterior cerebral artery
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is I66.12 an HCC code?
No. I66.12 is a billable ICD-10-CM code but does not map to any HCC category in V28, V24, ESRD, or RxHCC.
This code does not map to an HCC category in any model (V28, V24, ESRD, RxHCC).
What This Code Means
I66.12 is the ICD-10-CM diagnosis code for occlusion and stenosis of left anterior cerebral artery. A blockage or narrowing of the left anterior cerebral artery, which supplies the front portion of the brain. I66.12 sits in the ICD-10-CM chapter for diseases of the circulatory system (i00-i99), within the section covering cerebrovascular diseases (i60-i69).
I66.12 is a billable ICD-10-CM code but does not map to a payment HCC under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can be reported on Medicare Advantage encounter data submissions but it does not contribute to a beneficiary's RAF score and therefore does not affect risk-adjusted payments to the plan.
Verify left-sided location is documented to differentiate from right-sided occlusion.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for I66.12 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Verify left-sided location is documented to differentiate from right-sided occlusion
- •Anterior cerebral artery occlusion may present with different neurological symptoms than middle cerebral artery involvement