Skip to content
HCC Buddy home

I20.1 ICD-10-CM Code: Angina pectoris with documented spasm

I20.1 is not a CMS-HCC payment code. MEAT criteria · RAF calculator · free HCC coding tools

ICD-10-CM Code View

HCC Buddy Code Card

Digital ICD-10 code-book layout with official code detail, always-visible risk models, Code Trumping, and Buddy coding guidance.

FY 2026 Apr update / Diseases of the circulatory system (I00-I99) / Ischemic heart diseases (I20-I25)

I20.1

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

Angina pectoris with documented spasm

Chest pain caused by temporary narrowing of heart blood vessels due to spasm, confirmed by cardiac testing or clinical documentation.

Buddy the Bee presenting code insight

Buddy Insight

Angina pectoris with documented spasm, also known as Prinzmetal angina or variant angina, is caused by transient coronary artery vasospasm that temporarily reduces blood flow.

CMS-HCC V28

N/A

—

Not mapped

CMS-HCC V24

HCC 88

RAF 0.135

ACA/HHS

N/A

—

Not mapped

ESRD/PACE

HCC 88

RAF 0.043

RXHCC

HCC 188

RAF 0.052

Code Book Path

Official
I20Angina pectoris
I20.1Angina pectoris with documented spasm

Inclusion Terms

Official
  • Angiospastic angina
  • Prinzmetal angina
  • Spasm-induced angina
  • Variant angina

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for I20.1 in this effective period.

Related Child Codes

Official
I20.0Unstable angina
I20.2Refractory angina pectoris
I20.8Other forms of angina pectoris
I20.9Angina pectoris, unspecified

Includes

Official

ICD-10-CM does not list Includes notes for I20.1 in this effective period.

Excludes 1

Official
  • angina pectoris with atherosclerotic heart disease of native coronary arteries (I25.1-)
  • atherosclerosis of coronary artery bypass graft(s) and coronary artery of transplanted heart with angina pectoris (I25.7-)
  • postinfarction angina (I23.7)

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for I20.1 in this effective period.

Use Additional

Official
  • code to identify:
  • exposure to environmental tobacco smoke (Z77.22)
  • history of tobacco dependence (Z87.891)
  • occupational exposure to environmental tobacco smoke (Z57.31)
  • tobacco dependence (F17.-)

Code Also

Official

ICD-10-CM does not list Code Also instructions for I20.1 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance
Provider documentation of angina due to coronary artery vasospasm
ECG evidence of transient ST-segment elevation during episodes (characteristic finding)
Documentation of symptom pattern (rest angina, nocturnal, cyclic)
Provocative testing results if performed (ergonovine or acetylcholine challenge)

MEAT Support

HCC Buddy guidance
Provider documentation of angina due to coronary artery vasospasm
ECG evidence of transient ST-segment elevation during episodes (characteristic finding)
Documentation of symptom pattern (rest angina, nocturnal, cyclic)
Provocative testing results if performed (ergonovine or acetylcholine challenge)

Audit Caution

HCC Buddy guidance
Confusing vasospastic angina with unstable angina — while both can present at rest, the mechanism and treatment differ significantly
Coding as unspecified angina when vasospasm has been documented
Not recognizing that Prinzmetal angina and variant angina are the same condition as angina with documented spasm
Failing to document the provocative testing or ECG evidence that confirms the vasospastic mechanism

Common Mistakes

HCC Buddy guidance
I20.0 — Unstable angina (acute destabilization; vasospastic angina has a different mechanism and treatment)
I20.2 — Refractory angina pectoris (chronic intractable pain despite treatment)
I20.81 — Angina with coronary microvascular dysfunction (microvascular, not epicardial spasm)
I25.110-I25.119 — Atherosclerotic heart disease with angina (fixed obstruction, not vasospasm)

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 I20.1 an HCC code?

Yes. I20.1 maps to Angina Pectoris under the V24 model but is not retained in V28.

Code
I20.1
Description
Angina pectoris with documented spasm
HCC (V28)
No CMS-HCC V28 mapping
RAF
—
Billable
Yes
Payment year
2026

HCC Category Mapping

V24HCC 88, Angina Pectoris
0.135
ESRDHCC 88, Angina Pectoris
0.043
RxHCCHCC 188, Coronary Artery Disease and Angina
0.052

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 I20.1 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for I20.1

For I20.1 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 I20.1 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

Get the V28 RAF + MEAT cheat sheet

One printable page: confirm a code's V28 HCC status, its RAF weight, and the MEAT your note needs to make it stick. Free, no card.

Free PDF. No card. Unsubscribe anytime.

What This Code Means

I20.1 is the ICD-10-CM diagnosis code for angina pectoris with documented spasm. Chest pain caused by temporary narrowing of heart blood vessels due to spasm, confirmed by cardiac testing or clinical documentation. I20.1 sits in the ICD-10-CM chapter for diseases of the circulatory system (i00-i99), within the section covering ischemic heart diseases (i20-i25).

Under the older CMS-HCC V24 model, I20.1 maps to Angina Pectoris (HCC 88) with a community, non-dual, aged base RAF weight of 0.135. 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 explicitly mentions coronary vasospasm or Prinzmetal's angina. Because I20.1 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 I20.1 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

  • •Ensure documentation explicitly mentions coronary vasospasm or Prinzmetal's angina
  • •This type of angina often occurs at rest or during sleep and may respond to calcium channel blockers

Clinical Significance

Angina pectoris with documented spasm, also known as Prinzmetal angina or variant angina, is caused by transient coronary artery vasospasm that temporarily reduces blood flow. This occurs typically at rest, often in the early morning hours, and is distinguished from classic atherosclerotic angina by its mechanism. Treatment focuses on calcium channel blockers and nitrates rather than typical antiplatelet strategies.

Documentation Requirements

  • ✓Provider documentation of angina due to coronary artery vasospasm
  • ✓ECG evidence of transient ST-segment elevation during episodes (characteristic finding)
  • ✓Documentation of symptom pattern (rest angina, nocturnal, cyclic)
  • ✓Provocative testing results if performed (ergonovine or acetylcholine challenge)
  • ✓Coronary angiography results showing spasm or normal/near-normal coronaries
  • ✓Current treatment plan (calcium channel blockers, nitrates)
  • ✓Documentation distinguishing from fixed obstructive coronary disease

Commonly Confused Codes

  • •I20.0: Unstable angina (acute destabilization; vasospastic angina has a different mechanism and treatment)
  • •I20.2: Refractory angina pectoris (chronic intractable pain despite treatment)
  • •I20.81: Angina with coronary microvascular dysfunction (microvascular, not epicardial spasm)
  • •I25.110-I25.119: Atherosclerotic heart disease with angina (fixed obstruction, not vasospasm)
  • •I20.9: Angina pectoris, unspecified (less specific; use I20.1 when vasospasm is confirmed)

Child Codes

I20.0Unstable angina
HCC 229
I20.1Angina pectoris with documented spasm
I20.2Refractory angina pectoris
I20.8Other forms of angina pectoris
I20.9Angina pectoris, unspecified

Code Hierarchy

└I20Angina pectoris└I20.1Angina pectoris with documented spasm
└I20.1Angina pectoris with documented spasm

Because I20.1 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.

More on I20.1

Related condition guides

Work I20.1 in HCC Buddy

Open I20.1 in the Code Book for the full Index-to-Tabular path, MEAT checklist, and V28 HCC mapping, or in the Encoder to code from a keyword search. Pro includes 7 days to try everything, no card required.

Open in Code BookOpen in EncoderStart Pro