What is ICD-10 code I77.70?

I77.70 is the ICD-10-CM diagnosis code for Dissection of unspecified artery. A tear in the inner lining of an artery wall at an unspecified location, which can cause blood to leak between the layers and potentially block blood flow. I77.70 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. I77.70 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. I77.70 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. I77.70 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 I77.70 map to under V28?

I77.70 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 I77.70 pay in RAF?

I77.70 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 I77.70?

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. I77.70 was a payment HCC under V24 (Vascular Disease with Complications) 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 I77.70: Dissection of unspecified

I77.70 is not a CMS-HCC payment code. MEAT criteria · RAF calculator · free HCC coding tools

ICD-10-CM Code View

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Code lookupI77.70Effective 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)

I77.70

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

Dissection of unspecified artery

A tear in the inner lining of an artery wall at an unspecified location, which can cause blood to leak between the layers and potentially block blood flow.

Buddy Insight

Dissection of an unspecified artery is a serious vascular emergency where the inner lining of an artery tears, allowing blood to flow between the layers and potentially causing rupture or occlusion.

CMS-HCC V28

N/A

—

Not risk-adjusted for this model/period.

Not mapped

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

I77Other disorders of arteries and arterioles

I77.7Other arterial dissection

I77.70Dissection of unspecified artery

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for I77.70 in this effective period.

Excludes 2

Official

dissection of aorta (I71.0-)
dissection of coronary artery (I25.42)

Related Child Codes

Official

I77.71Dissection of carotid artery

I77.72Dissection of iliac artery

I77.73Dissection of renal artery

I77.74Dissection of vertebral artery

I77.75Dissection of other precerebral arteries

Includes

Official

ICD-10-CM does not list Includes notes for I77.70 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for I77.70 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for I77.70 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for I77.70 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for I77.70 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Documentation of arterial dissection confirmed by imaging (CT angiography, magnetic resonance angiography, or conventional angiography)

Identification of the affected artery (query provider if documented as unspecified)

Acuity — whether acute, subacute, or chronic/healed dissection

Current treatment plan including anticoagulation, blood pressure management, or surgical intervention

MEAT Support

HCC Buddy guidance

Documentation of arterial dissection confirmed by imaging (CT angiography, magnetic resonance angiography, or conventional angiography)

Identification of the affected artery (query provider if documented as unspecified)

Acuity — whether acute, subacute, or chronic/healed dissection

Current treatment plan including anticoagulation, blood pressure management, or surgical intervention

Audit Caution

HCC Buddy guidance

Using this unspecified code when the provider has documented the specific artery involved

Failing to query for laterality and specific vessel when documentation supports more detail

Not distinguishing between acute and chronic dissection which affects management

Confusing arterial dissection with aortic dissection — aortic dissections have their own specific codes in I71

Common Mistakes

HCC Buddy guidance

I77.71-I77.79 — Dissection of specific arteries: use when the specific artery is documented

I71.00-I71.03 — Dissection of aorta: use specifically for aortic dissection

I74.x — Arterial embolism and thrombosis: occlusion mechanism differs from dissection

I77.5 — Necrosis of artery: tissue death rather than intimal tear

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 I77.70 an HCC code?

Yes. I77.70 maps to Vascular Disease with Complications under the V24 model but is not retained in V28.

Code: I77.70
Description: Dissection of unspecified artery
HCC (V28): No CMS-HCC V28 mapping
RAF: —
Billable: Yes
Payment year: 2026

HCC Category Mapping

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 I77.70 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for I77.70

For I77.70 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 I77.70 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

I77.70 is the ICD-10-CM diagnosis code for dissection of unspecified artery. A tear in the inner lining of an artery wall at an unspecified location, which can cause blood to leak between the layers and potentially block blood flow. I77.70 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, I77.70 maps to Vascular Disease with Complications (HCC 107) with a community, non-dual, aged base RAF weight of 0.383. 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.

This is a non-specific code; use more specific dissection codes (I77.71-I77.73) when the artery location is documented. Because I77.70 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 I77.70 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•This is a non-specific code; use more specific dissection codes (I77.71-I77.73) when the artery location is documented
•Document symptoms such as pain, which may help identify the affected artery

Clinical Significance

Dissection of an unspecified artery is a serious vascular emergency where the inner lining of an artery tears, allowing blood to flow between the layers and potentially causing rupture or occlusion. This maps to vascular disease with complications, reflecting the acute severity and high resource utilization. Providers should be queried for the specific artery involved to improve coding specificity.

Documentation Requirements

✓Documentation of arterial dissection confirmed by imaging (CT angiography, magnetic resonance angiography, or conventional angiography)
✓Identification of the affected artery (query provider if documented as unspecified)
✓Acuity — whether acute, subacute, or chronic/healed dissection
✓Current treatment plan including anticoagulation, blood pressure management, or surgical intervention
✓Assessment of complications such as ischemia, hemorrhage, or organ damage

Commonly Confused Codes

•I77.71-I77.79: Dissection of specific arteries: use when the specific artery is documented
•I71.00-I71.03: Dissection of aorta: use specifically for aortic dissection
•I74.x: Arterial embolism and thrombosis: occlusion mechanism differs from dissection
•I77.5: Necrosis of artery: tissue death rather than intimal tear