What is ICD-10 code I77.3?

I77.3 is the ICD-10-CM diagnosis code for Arterial fibromuscular dysplasia. A genetic condition where the muscular layer of arteries develops abnormally, causing irregular narrowing and widening of the vessel that can restrict blood flow. It belongs to the ICD-10-CM chapter for diseases of the circulatory system (i00-i99). I77.3 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. I77.3 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. I77.3 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. I77.3 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.

Which HCC does I77.3 map to under V28?

I77.3 does not map to a CMS-HCC V28 payment category. Check the current CMS-HCC V28 model file for payment year 2026 rather than an older V24 tip sheet.

What does I77.3 pay in RAF?

I77.3 has no separately stated V28 community RAF weight. If it is not a V28 payment HCC, it adds nothing to a community RAF score.

What is the V28 vs V24 difference for I77.3?

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. I77.3 was a payment HCC under V24 (Vascular Disease) but the V28 recalibration removed it from the risk adjustment model. Both models can still appear in legacy data and in payer-specific lookback periods.

2026 ICD-10-CM I77.3: Arterial fibromuscular

I77.3 is not a CMS-HCC payment code. MEAT criteria · RAF calculator · HCC coding software

ICD-10-CM Code View

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Code lookupI77.3Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Diseases of the circulatory system (I00-I99) / Diseases of arteries, arterioles and capillaries (I70-I79)

I77.3

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

Arterial fibromuscular dysplasia

A genetic condition where the muscular layer of arteries develops abnormally, causing irregular narrowing and widening of the vessel that can restrict blood flow.

Buddy Insight

Arterial fibromuscular dysplasia is a non-atherosclerotic, non-inflammatory vascular disease causing abnormal cell growth in artery walls, leading to stenosis, aneurysm, or dissection.

CMS-HCC V28

N/A

—

Not risk-adjusted for this model/period.

Not mapped

CMS-HCC V24

Mapped

HCC 108

Vascular Disease

RAF 0.288

ACA/HHS

N/A

—

Not risk-adjusted for this model/period.

Not mapped

ESRD/PACE

Mapped

HCC 108

Vascular Disease

RAF 0.073

RXHCC

N/A

—

Not risk-adjusted for this model/period.

Not mapped

Code Book Path

Official

I77Other disorders of arteries and arterioles

I77.3Arterial fibromuscular dysplasia

Inclusion Terms

Official

Fibromuscular hyperplasia (of) carotid artery
Fibromuscular hyperplasia (of) renal artery

Excludes 2

Official

collagen (vascular) diseases (M30-M36)
hypersensitivity angiitis (M31.0)
pulmonary artery (I28.-)

Related Child Codes

Official

I77.0Arteriovenous fistula, acquired

I77.1Stricture of artery

I77.2Rupture of artery

I77.4Celiac artery compression syndrome

I77.5Necrosis of artery

Includes

Official

ICD-10-CM does not list Includes notes for I77.3 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for I77.3 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for I77.3 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for I77.3 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for I77.3 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Documentation of fibromuscular dysplasia diagnosis

Affected artery or arteries (renal, carotid, vertebral, iliac, others)

Imaging findings (classic 'string of beads' appearance on angiography)

Type classification when documented (medial fibroplasia is most common)

MEAT Support

HCC Buddy guidance

Documentation of fibromuscular dysplasia diagnosis

Affected artery or arteries (renal, carotid, vertebral, iliac, others)

Imaging findings (classic 'string of beads' appearance on angiography)

Type classification when documented (medial fibroplasia is most common)

Audit Caution

HCC Buddy guidance

Coding as atherosclerotic disease when documentation specifically states fibromuscular dysplasia

Not coding associated complications (renal artery stenosis, dissection, aneurysm) separately

Missing this diagnosis when 'string of beads' appearance is described in imaging but the clinical note uses different terminology

Not recognizing that fibromuscular dysplasia can affect multiple vascular beds simultaneously — code each affected territory

Common Mistakes

HCC Buddy guidance

I77.1 — Stricture of artery: non-specific arterial stricture — use I77.3 when fibromuscular dysplasia is documented

I70.x — Atherosclerosis: atherosclerotic stenosis is a fundamentally different pathology

I72.0 — Aneurysm of carotid artery: aneurysm secondary to fibromuscular dysplasia should code both conditions

I72.2 — Aneurysm of renal artery: renal artery aneurysm from fibromuscular dysplasia should code both

Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →

Is I77.3 an HCC code?

Yes. I77.3 maps to Vascular Disease under the V24 model but is not retained in V28.

Code: I77.3
Description: Arterial fibromuscular dysplasia
HCC (V28): No CMS-HCC V28 mapping
RAF: —
Billable: Yes
Payment year: 2026

HCC Category Mapping

V24HCC 108, Vascular Disease

0.288

ESRDHCC 108, Vascular Disease

0.073

Each model's RAF is its CMS base weight for that model's standard population, so weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. 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.

Work I77.3 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for I77.3

For I77.3 to 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 I77.3 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

I77.3 is the ICD-10-CM diagnosis code for arterial fibromuscular dysplasia. A genetic condition where the muscular layer of arteries develops abnormally, causing irregular narrowing and widening of the vessel that can restrict blood flow. I77.3 sits in the ICD-10-CM chapter for diseases of the circulatory system (i00-i99), within the section covering diseases of arteries, arterioles and capillaries (i70-i79).

Under the older CMS-HCC V24 model, I77.3 maps to Vascular Disease (HCC 108) with a community, non-dual, aged base RAF weight of 0.288. 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.

Specify the affected artery location (renal, carotid, etc.) when documented. Because I77.3 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 I77.3 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Specify the affected artery location (renal, carotid, etc.) when documented
•This is often discovered incidentally during imaging for other conditions

Clinical Significance

Arterial fibromuscular dysplasia is a non-atherosclerotic, non-inflammatory vascular disease causing abnormal cell growth in artery walls, leading to stenosis, aneurysm, or dissection. Most commonly affecting the renal and carotid arteries, it is a significant cause of secondary hypertension and stroke in younger patients, particularly women. Accurate coding is essential as this represents a distinct vascular pathology requiring specific management.

Documentation Requirements

✓Documentation of fibromuscular dysplasia diagnosis
✓Affected artery or arteries (renal, carotid, vertebral, iliac, others)
✓Imaging findings (classic 'string of beads' appearance on angiography)
✓Type classification when documented (medial fibroplasia is most common)
✓Associated complications (hypertension, dissection, aneurysm)
✓Treatment plan (antihypertensives, antiplatelet therapy, angioplasty if indicated)

Commonly Confused Codes

•I77.1: Stricture of artery: non-specific arterial stricture: use I77.3 when fibromuscular dysplasia is documented
•I70.x: Atherosclerosis: atherosclerotic stenosis is a fundamentally different pathology
•I72.0: Aneurysm of carotid artery: aneurysm secondary to fibromuscular dysplasia should code both conditions
•I72.2: Aneurysm of renal artery: renal artery aneurysm from fibromuscular dysplasia should code both