What is ICD-10 code I75.021?

I75.021 is the ICD-10-CM diagnosis code for Atheroembolism of right lower extremity. It belongs to the ICD-10-CM chapter for diseases of the circulatory system (i00-i99). I75.021 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. I75.021 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. I75.021 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. I75.021 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 I75.021 map to under V28?

I75.021 maps to CMS-HCC V28 264 (Vascular Disease with Complications). The category number and label come from the CMS-HCC V28 model file for payment year 2026.

What does I75.021 pay in RAF?

I75.021 carries a community, non-dual, aged (CNA) RAF weight of 0.455 under CMS-HCC V28 for payment year 2026. The weight comes from the CMS V28 relative-factor file, not a hand-typed table.

What is the V28 vs V24 difference for I75.021?

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 I75.021, V28 maps to Vascular Disease with Complications at RAF 0.455 while V24 mapped to Vascular Disease with Complications at RAF 0.383. Both models can still appear in legacy data and in payer-specific lookback periods.

What documentation supports I75.021?

Verify documentation specifies the RIGHT lower extremity, as laterality is required for accurate coding; if bilateral, code both sides separately with appropriate laterality indicators Confirm the clinical documentation distinguishes between atheroembolism (plaque/cholesterol emboli) and other types of emboli; review imaging or pathology reports to support the diagnosis Because I75.021 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. See the MEAT criteria checklist at /meat-criteria for what Monitor, Evaluate, Assess, or Treat looks like in a note. MEAT is generic documentation evidence, not a payer-specific rule.

2026 ICD-10-CM I75.021: Atheroembolism

I75.021 maps to CMS-HCC V28 264 (RAF 0.455). Documentation must support MEAT. MEAT criteria · RAF calculator · free HCC coding tools

ICD-10-CM Code View

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Code lookupI75.021Effective 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)

I75.021

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

Atheroembolism of right lower extremity

A blood clot or plaque fragment from an artery has broken loose and lodged in a blood vessel of the right leg, blocking blood flow to that area. This is a serious condition that can cause pain, tissue damage, or loss of limb function if not treated promptly.

Buddy Insight

CMS-HCC V28

Mapped

HCC 264

Vascular Disease with Complic...

RAF 0.455

CMS-HCC V24

Mapped

HCC 107

Vascular Disease with Complic...

RAF 0.383

ACA/HHS

Mapped

HCC 154

HHS-HCC 154

Varies by metal level

ESRD/PACE

Mapped

HCC 107

Vascular Disease with Complic...

RAF 0.144

RXHCC

N/A

—

Not risk-adjusted for this model/period.

Not mapped

Code Book Path

Official

I75.0Atheroembolism of extremities

I75.02Atheroembolism of lower extremity

I75.021Atheroembolism of right lower extremity

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for I75.021 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for I75.021 in this effective period.

Related Child Codes

Official

I75.022Atheroembolism of left lower extremity

I75.023Atheroembolism of bilateral lower extremities

I75.029Atheroembolism of unspecified lower extremity

Includes

Official

ICD-10-CM does not list Includes notes for I75.021 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for I75.021 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for I75.021 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for I75.021 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for I75.021 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Documentation of atheroembolism affecting the right lower extremity

Clinical findings (blue toe syndrome, livedo reticularis, digital gangrene, painful nodules)

Source identification (abdominal aortic or iliac atherosclerotic disease)

Precipitating event if applicable (angiography, vascular surgery, anticoagulation)

MEAT Support

HCC Buddy guidance

Documentation of atheroembolism affecting the right lower extremity

Clinical findings (blue toe syndrome, livedo reticularis, digital gangrene, painful nodules)

Source identification (abdominal aortic or iliac atherosclerotic disease)

Precipitating event if applicable (angiography, vascular surgery, anticoagulation)

Audit Caution

HCC Buddy guidance

Coding blue toe syndrome as peripheral arterial disease rather than atheroembolism when the presentation is embolic

Using unspecified laterality when right side is clearly documented

Confusing atheroembolism-related gangrene with chronic ischemic gangrene from peripheral arterial disease

Not coding the precipitating procedure or anticoagulation therapy that triggered the embolic event

Common Mistakes

HCC Buddy guidance

I75.022 — Atheroembolism of left lower extremity: opposite laterality

I75.029 — Atheroembolism of unspecified lower extremity: use right-specific code when documented

I74.3 — Embolism and thrombosis of arteries of the lower extremities: general thromboembolism, not specifically cholesterol-based

I70.261 — Atherosclerosis of native arteries of extremities with gangrene, right leg: chronic atherosclerotic gangrene, not embolic

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 I75.021 an HCC code?

Yes. I75.021 (Atheroembolism of right lower extremity) maps to Vascular Disease with Complications under the CMS-HCC V28 risk adjustment model (and Vascular Disease with Complications under V24), with a community non-dual aged RAF of 0.455. It is billable for payment year 2026.

Coder answer: I75.021 is billable and maps to V28 HCC 264, Vascular Disease with Complications. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.

Code: I75.021
Description: Atheroembolism of right lower extremity
HCC (V28): HCC 264 — Vascular Disease with Complications
RAF: 0.455
Billable: Yes
Payment year: 2026

HCC Category Mapping

V28HCC 264, Vascular Disease with Complications

0.455

V24HCC 107, Vascular Disease with Complications

0.383

ESRDHCC 107, Vascular Disease with Complications

0.144

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 I75.021 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for I75.021

For I75.021 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 I75.021 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

I75.021 is the ICD-10-CM diagnosis code for atheroembolism of right lower extremity. A blood clot or plaque fragment from an artery has broken loose and lodged in a blood vessel of the right leg, blocking blood flow to that area. This is a serious condition that can cause pain, tissue damage, or loss of limb function if not treated promptly. I75.021 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 CMS-HCC V28 risk adjustment model, I75.021 maps to Vascular Disease with Complications (HCC 264) with a community, non-dual, aged base RAF weight of 0.455. Under the older V24 model, I75.021 mapped to the same category but with a base RAF weight of 0.383, 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.

Verify documentation specifies the RIGHT lower extremity, as laterality is required for accurate coding; if bilateral, code both sides separately with appropriate laterality indicators. Because I75.021 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 I75.021 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Verify documentation specifies the RIGHT lower extremity, as laterality is required for accurate coding; if bilateral, code both sides separately with appropriate laterality indicators
•Confirm the clinical documentation distinguishes between atheroembolism (plaque/cholesterol emboli) and other types of emboli; review imaging or pathology reports to support the diagnosis

Clinical Significance

Atheroembolism of the right lower extremity is the most common presentation of cholesterol embolization syndrome, often manifesting as blue toe syndrome, livedo reticularis, or digital gangrene in the right foot and leg. It typically originates from aortic or iliac atherosclerotic disease and may be triggered by vascular procedures or anticoagulation. This condition indicates severe systemic atherosclerosis.

Documentation Requirements

✓Documentation of atheroembolism affecting the right lower extremity
✓Clinical findings (blue toe syndrome, livedo reticularis, digital gangrene, painful nodules)
✓Source identification (abdominal aortic or iliac atherosclerotic disease)
✓Precipitating event if applicable (angiography, vascular surgery, anticoagulation)
✓Laboratory findings (eosinophilia, elevated creatinine, elevated lactate dehydrogenase)
✓Tissue viability assessment and treatment plan

Commonly Confused Codes

•I75.022: Atheroembolism of left lower extremity: opposite laterality
•I75.029: Atheroembolism of unspecified lower extremity: use right-specific code when documented
•I74.3: Embolism and thrombosis of arteries of the lower extremities: general thromboembolism, not specifically cholesterol-based
•I70.261: Atherosclerosis of native arteries of extremities with gangrene, right leg: chronic atherosclerotic gangrene, not embolic