ICD-10-CM 2027 diagnosis code
I20.0Unstable angina
I20.0 is a valid, billable ICD-10-CM code for unstable angina. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.
Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data
About I20.0
I20.0 is the ICD-10-CM diagnosis code for unstable angina. It belongs to category I20 (angina pectoris), block I20-I25 (ischemic heart diseases) and chapter 9 (diseases of the circulatory system). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.
Within I20 (angina pectoris), I20.0 is specifically for unstable angina. Related codes cover with documented spasm (I20.1), refractory angina pectoris (I20.2), other forms of angina pectoris (I20.8) and unspecified (I20.9).
Use an additional 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.-) and tobacco use (Z72.0).
As a secondary diagnosis it is a CC (complication or comorbidity), which can move an inpatient stay into the "with CC" MS-DRG of its family, unless the principal diagnosis excludes it.
In MS-DRG v44.0, it is part of the grouping logic for DRG 311 (Angina Pectoris, relative weight 0.6684), in MDC 05 (Diseases and Disorders of the Circulatory System), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.
It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.
Before ICD-10, this condition was coded in ICD-9-CM as 411.1 (intermediate coronary syndrome).
Coding notes
- Accelerated angina
- Crescendo angina
- De novo effort angina
- Intermediate coronary syndrome
- Preinfarction syndrome
- Worsening effort angina
Notes that apply from higher levels
Instructions written at a parent level also apply to I20.0.
› From I20 Angina pectoris
Broader instructions also apply from I20-I25 Ischemic heart diseases and Chapter 9: Diseases of the circulatory system.
Alphabetic index entries
8 entriesTerms in the official ICD-10-CM index that lead to I20.0.
- Angina (attack) (cardiac) (chest) (heart) (pectoris) (syndrome) (vasomotor) › unstable
- Impending › coronary syndrome
- Impending › myocardial infarction
- Infarct, infarction › impending (myocardium)
- Syndrome › coronary › insufficiency or intermediate
- Syndrome › impending coronary
- Syndrome › intermediate coronary (artery)
- Syndrome › preinfarction
Codes whose notes reference I20.0
MS-DRG v44.0 grouping
All DRGs →Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.
MDC 05 · Diseases and Disorders of the Circulatory System
ICD-9-CM equivalent
Converter →- 411.1Intermediate coronary syndromeapproximate
From the CMS 2018 General Equivalence Mappings (GEMs), the final GEMs release.
Code history
- 2016
- 2017
- 2018
- 2019
- 2020
- 2021
- 2022
- 2023
- 2024
- 2025
- 2026
- 2027
- FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
- No changes since FY2016.
Common questions about I20.0
Is I20.0 billable?
- Yes. I20.0 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can I20.0 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict I20.0 as a principal diagnosis.
Is I20.0 a CC or MCC?
- I20.0 is a CC (complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.
What DRG does I20.0 group to?
- I20.0 is used in the MS-DRG v44.0 logic for MS-DRG 311 (Angina Pectoris). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.
What is the ICD-9 code for I20.0?
- The CMS General Equivalence Mappings map I20.0 to ICD-9-CM 411.1.