G45.1
BillableCarotid artery syndrome (hemispheric)
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is G45.1 an HCC code?
No. G45.1 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
G45.1 is the ICD-10-CM diagnosis code for carotid artery syndrome (hemispheric). A temporary reduction in blood flow through the carotid artery affecting one side of the brain, causing brief neurological symptoms like weakness or vision loss. G45.1 sits in the ICD-10-CM chapter for diseases of the nervous system (g00-g99), within the section covering episodic and paroxysmal disorders (g40-g47).
G45.1 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.
Document laterality (left or right) and specific transient symptoms to support the diagnosis.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for G45.1 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Document laterality (left or right) and specific transient symptoms to support the diagnosis
- •Confirm symptoms resolved completely and distinguish from amaurosis fugax if vision loss is the only symptom