I24.81 ICD-10-CM Code: Acute coronary microvascular dysfunction
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)
I24.81
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceAcute coronary microvascular dysfunction
Dysfunction of the smallest blood vessels in the heart that occurs acutely, reducing blood flow without a traditional heart attack.
Buddy Insight
Acute coronary microvascular dysfunction represents a condition where the small blood vessels of the heart fail to dilate properly, causing chest pain and ischemia without obstruction of the larger coronary arteries.
CMS-HCC V28
MappedHCC 229
RAF 0.0
CMS-HCC V24
MappedHCC 87
RAF 0.274
ACA/HHS
00
RAF 0
ESRD/PACE
MappedHCC 87
RAF 0.0
RXHCC
MappedHCC 188
RAF 0.0
Code Trumping
Basket needed
Code Book Path
Inclusion Terms
Official- Acute (presentation of) coronary microvascular disease
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for I24.81 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for I24.81 in this effective period.
Excludes 1
Official- myocardial infarction due to demand ischemia (I21.A1)
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for I24.81 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for I24.81 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for I24.81 in this effective period.
Buddy Documentation Tip
MEAT Support
Audit Caution
Common Mistakes
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 I24.81 an HCC code?
Yes. I24.81 maps to Unstable Angina and Other Acute Ischemic Heart Disease under the CMS-HCC V28 risk adjustment model (and Unstable Angina and Other Acute Ischemic Heart Disease under V24).
HCC Category Mapping
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.
MEAT Criteria for I24.81
For I24.81to 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 I24.81 during that encounter, not just copy-forwarded from a problem list.
What This Code Means
I24.81 is the ICD-10-CM diagnosis code for acute coronary microvascular dysfunction. Dysfunction of the smallest blood vessels in the heart that occurs acutely, reducing blood flow without a traditional heart attack. I24.81 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 CMS-HCC V28 risk adjustment model, I24.81 maps to Unstable Angina and Other Acute Ischemic Heart Disease (HCC 229) with a community, non-dual, aged base RAF weight of 0.000. Under the older V24 model, I24.81 mapped to the same category but with a base RAF weight of 0.274, 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.
This represents microvascular dysfunction rather than obstruction of larger coronary arteries. Because I24.81 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 I24.81 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •This represents microvascular dysfunction rather than obstruction of larger coronary arteries
- •Document clinical presentation and any diagnostic findings (stress testing, imaging) that support microvascular dysfunction
Clinical Significance
Acute coronary microvascular dysfunction represents a condition where the small blood vessels of the heart fail to dilate properly, causing chest pain and ischemia without obstruction of the larger coronary arteries. This newer code reflects growing recognition that microvascular disease is an important cause of acute cardiac presentations, particularly in women. It is distinct from myocardial infarction with microvascular dysfunction (I21.B) because no myocardial necrosis occurs.
Documentation Requirements
- ✓Documentation of acute coronary microvascular dysfunction
- ✓Evidence that large coronary arteries are non-obstructive (normal or near-normal on angiography)
- ✓Clinical symptoms of acute ischemia (chest pain, dyspnea)
- ✓Diagnostic testing supporting microvascular dysfunction (coronary flow reserve testing, index of microcirculatory resistance)
- ✓Exclusion of myocardial infarction (normal troponin levels)
- ✓Acute presentation documented
Commonly Confused Codes
- •I21.B: Myocardial infarction with coronary microvascular dysfunction: includes actual myocardial necrosis
- •I20.0: Unstable angina: general unstable angina without microvascular dysfunction specification
- •I20.1: Angina pectoris with documented spasm: vasospasm of epicardial arteries, not microvascular
- •I25.89: Other forms of chronic ischemic heart disease: chronic condition, not acute
- •I24.89: Other forms of acute ischemic heart disease: less specific