What is ICD-10 code I70.221?

I70.221 is the ICD-10-CM diagnosis code for Atherosclerosis of native arteries of extremities with rest pain, right leg. It belongs to the ICD-10-CM chapter for diseases of the circulatory system (i00-i99). I70.221 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. I70.221 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. I70.221 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. I70.221 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.

What is the V28 vs V24 difference for I70.221?

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 I70.221, V28 maps to Vascular Disease with Complications at RAF 0.455 while V24 mapped to Vascular Disease at RAF 0.288. Both models can still appear in legacy data and in payer-specific lookback periods.

What should coders know when reporting I70.221?

Ensure documentation specifies 'rest pain' as the symptom, distinguishing it from claudication (pain with activity), as this affects severity coding Verify laterality is documented as right leg; if bilateral disease exists, code both sides separately with appropriate laterality indicators (I70.221 for right, I70.222 for left) Because I70.221 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.

I70.221: Atherosclerosis of native arteries of extremities with rest pain, right leg — ICD-10

ICD-10-CM Code View

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Code lookupI70.221Effective 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)

I70.221

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

Atherosclerosis of native arteries of extremities with rest pain, right leg

This condition occurs when fatty deposits build up in the arteries of the right leg, narrowing blood flow and causing pain even when the person is resting or not moving. It indicates moderate to severe atherosclerotic disease affecting the leg's blood supply.

Buddy Insight

CMS-HCC V28

Mapped

HCC 264

Vascular Disease with Complic...

RAF 0.455

CMS-HCC V24

Mapped

HCC 108

Vascular Disease

RAF 0.288

ACA/HHS

Not risk-adjusted for this model/period.

RAF 0

ESRD/PACE

Mapped

HCC 108

Vascular Disease

RAF 0.0

RXHCC

Not risk-adjusted for this model/period.

RAF 0

Code Trumping

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Code Book Path

Official

I70.2Atherosclerosis of native arteries of the extremities

I70.22Atherosclerosis of native arteries of extremities with rest pain

I70.221Atherosclerosis of native arteries of extremities with rest pain, right leg

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for I70.221 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for I70.221 in this effective period.

Related Child Codes

Official

I70.222Atherosclerosis of native arteries of extremities with rest pain, left leg

I70.223Atherosclerosis of native arteries of extremities with rest pain, bilateral legs

I70.228Atherosclerosis of native arteries of extremities with rest pain, other extremity

I70.229Atherosclerosis of native arteries of extremities with rest pain, unspecified extremity

Includes

Official

any condition classifiable to I70.21-
chronic limb-threatening ischemia NOS of native arteries of extremities
chronic limb-threatening ischemia of native arteries of extremities with rest pain
critical limb ischemia NOS of native arteries of extremities
critical limb ischemia of native arteries of extremities with rest pain

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for I70.221 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for I70.221 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for I70.221 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for I70.221 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Documentation of the specific arterial site affected by atherosclerosis

Documentation that the patient experiences ischemic pain at rest, not just during exertion

Specification that the atherosclerosis involves native (not grafted or bypassed) arteries

Affected leg laterality must be documented (right, left, bilateral)

MEAT Support

HCC Buddy guidance

Documentation of the specific arterial site affected by atherosclerosis

Documentation that the patient experiences ischemic pain at rest, not just during exertion

Specification that the atherosclerosis involves native (not grafted or bypassed) arteries

Affected leg laterality must be documented (right, left, bilateral)

Audit Caution

HCC Buddy guidance

Failing to code ulceration or gangrene when present — rest pain codes (I70.22x) should not be used when tissue loss has progressed to ulceration (I70.23x-I70.24x) or gangrene (I70.26x), as these represent more advanced disease stages

Misclassifying rest pain as intermittent claudication — rest pain occurs at rest and is a sign of critical limb ischemia, while claudication is exertional; this distinction matters for V28 HCC mapping

Not distinguishing between native artery disease and bypass graft disease — I70.22x is exclusively for native arteries

Failing to specify laterality when documentation clearly identifies the affected leg

Common Mistakes

HCC Buddy guidance

I70.21x — Atherosclerosis of native arteries of extremities with intermittent claudication; use when pain occurs only with exertion, not at rest

I70.23x-I70.25x — Atherosclerosis of native arteries with ulceration or gangrene; use when tissue loss is present in addition to rest pain

I70.32x — Atherosclerosis of unspecified type of bypass graft of extremities with rest pain; use when the affected vessel is a bypass graft, not a native artery

I70.20x — Unspecified atherosclerosis of native arteries of extremities; use when no symptoms are documented; rest pain indicates much more severe disease

Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.

Is I70.221 an HCC code?

Yes. I70.221 maps to Vascular Disease with Complications under the CMS-HCC V28 risk adjustment model (and Vascular Disease under V24).

HCC Category Mapping

V28HCC 264, Vascular Disease with Complications

0.455

V24HCC 108, Vascular Disease

0.288

ESRDHCC 108, Vascular Disease

0.000

RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. 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 I70.221 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for I70.221

For I70.221to 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 I70.221 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

I70.221 is the ICD-10-CM diagnosis code for atherosclerosis of native arteries of extremities with rest pain, right leg. This condition occurs when fatty deposits build up in the arteries of the right leg, narrowing blood flow and causing pain even when the person is resting or not moving. It indicates moderate to severe atherosclerotic disease affecting the leg's blood supply. I70.221 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, I70.221 maps to Vascular Disease with Complications (HCC 264) with a community, non-dual, aged base RAF weight of 0.455. Under the older CMS-HCC V24 model, I70.221 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.

Ensure documentation specifies 'rest pain' as the symptom, distinguishing it from claudication (pain with activity), as this affects severity coding. Because I70.221 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 I70.221 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Ensure documentation specifies 'rest pain' as the symptom, distinguishing it from claudication (pain with activity), as this affects severity coding
•Verify laterality is documented as right leg; if bilateral disease exists, code both sides separately with appropriate laterality indicators (I70.221 for right, I70.222 for left)

Clinical Significance

Atherosclerosis of native arteries of the extremities with rest pain represents critical limb ischemia, a severe and limb-threatening stage of peripheral arterial disease where blood supply is insufficient even at rest. This condition carries a high risk of tissue loss, gangrene, and amputation, and typically requires urgent vascular intervention such as revascularization. In the V28 model, this code maps to HCC 264 with a RAF weight of 0.356, reflecting the significantly higher resource utilization and clinical complexity of critical limb ischemia compared to less severe peripheral arterial disease.

Documentation Requirements

✓Documentation of the specific arterial site affected by atherosclerosis
✓Documentation that the patient experiences ischemic pain at rest, not just during exertion
✓Specification that the atherosclerosis involves native (not grafted or bypassed) arteries
✓Affected leg laterality must be documented (right, left, bilateral)
✓Hemodynamic assessment results (ankle-brachial index, toe pressures, or transcutaneous oxygen measurements)
✓Assessment for tissue loss, ulceration, or gangrene (which would require a different, more specific code)
✓Vascular surgery or interventional radiology consultation and revascularization plan

Commonly Confused Codes

•I70.21x: Atherosclerosis of native arteries of extremities with intermittent claudication; use when pain occurs only with exertion, not at rest
•I70.23x-I70.25x: Atherosclerosis of native arteries with ulceration or gangrene; use when tissue loss is present in addition to rest pain
•I70.32x: Atherosclerosis of unspecified type of bypass graft of extremities with rest pain; use when the affected vessel is a bypass graft, not a native artery
•I70.20x: Unspecified atherosclerosis of native arteries of extremities; use when no symptoms are documented; rest pain indicates much more severe disease
•I96: Gangrene, not elsewhere classified; do not use when gangrene is specifically associated with atherosclerosis of extremities, which has its own codes