I20.0 — Unstable angina
I20.0 is a billable, specific ICD-10-CM code for unstable angina. It is valid for submission on a claim.
Inclusion terms
Alternative wordings a physician may use in the chart for this same code.
- Accelerated angina
- Crescendo angina
- De novo effort angina
- Intermediate coronary syndrome
- Preinfarction syndrome
- Worsening effort angina
Excludes1 inherited from the categories above I20.0
These are not written on I20.0, but they bind it: a note on a category applies to every code beneath it. Billing I20.0 with anything listed here is a denial.
Other codes that can never be billed with I20.0
These codes carry an Excludes1 note pointing at I20.0. The conflict binds both ways, but ICD-10-CM only writes it down on one side — so you would not find this by reading I20.0 alone.
- I24Other acute ischemic heart diseases
- I25.110Atherosclerotic heart disease of native coronary artery with unstable angina pectoris
- I25.700Atherosclerosis of coronary artery bypass graft(s), unspecified, with unstable angina pectoris
- I25.710Atherosclerosis of autologous vein coronary artery bypass graft(s) with unstable angina pectoris
- I25.720Atherosclerosis of autologous artery coronary artery bypass graft(s) with unstable angina pectoris
- I25.730Atherosclerosis of nonautologous biological coronary artery bypass graft(s) with unstable angina pectoris
- I25.790Atherosclerosis of other coronary artery bypass graft(s) with unstable angina pectoris
Risk adjustment
I20.0 risk-adjusts. Under the CMS-HCC V28 model it maps to this category:
- HCC 229 Unstable Angina and Other Acute Ischemic Heart Disease0.240 RAF
Coefficient shown for the Community Non-dual Aged segment. A higher HCC in the same hierarchy will suppress this one, so capturing it does not always add score.
Medicare coverage
I20.0 is named in 61 Medicare coverage policies — 61 listing it as supporting medical necessity. Which of them applies to you depends on your Medicare contractor, and coverage genuinely differs by state.
- A52850Billing and Coding: Cardiac Catheterization and Coronary Angiography
- A52850Billing and Coding: Cardiac Catheterization and Coronary Angiography
- A56423Billing and Coding: Cardiology Non-emergent Outpatient Stress Testing
- A56423Billing and Coding: Cardiology Non-emergent Outpatient Stress Testing
How I20.0 is indexed
Coders do not find codes by browsing the tabular list — they look them up in the alphabetic index, under the word the physician wrote. These are the index entries that lead here, so you can see which chart wordings map to I20.0.
- Angina›unstable
- Impending›coronary syndrome
- Impending›myocardial infarction
- Infarct, infarction›impending(myocardium)
- Syndrome›impending coronary
- Syndrome›intermediate coronary(artery)
- Syndrome›preinfarction
- Syndrome›coronary›insufficiency or intermediate
Code history
I20.0 has not changed since FY2024 — no addition, revision or deletion across the three most recent ICD-10-CM releases.
Related codes at this level
Codes that share I20. If I20.0 is not quite right, the correct code is usually one of these.
Questions about I20.0
- Is I20.0 a billable ICD-10-CM code?
- Yes. I20.0 is a billable, specific ICD-10-CM code and is valid for submission on a claim.
- Where does I20.0 sit in the tabular list?
- Diseases of the circulatory system (I00-I99), in the block Ischemic heart diseases (I20-I25).
- What cannot be coded together with I20.0?
- I20.0 carries Excludes1 notes, which means the conditions they list can never be coded together with it on the same encounter. Some are written on the categories above I20.0 (I20) and apply to it just the same.