ICD-10 I20.0
Billable / Specific HCC v28: 87 CCUnstable angina
About ICD-10-CM I20.0
ICD-10-CM code I20.0 represents Unstable angina. This is a billable/specific code in the Circulatory System chapter (block I20). The 2026 edition of ICD-10-CM I20.0 became effective on October 1, 2025.
Coding Tips for I20.0
Specialist guidance from the PayerReady Medical Coding Team. Specificity warnings, HCC capture rules, sequencing notes.
I20.0 is a CMS-HCC v28 risk-adjustment code (category 87). To count for the patient Risk Adjustment Factor (RAF), document the diagnosis with MEAT language each calendar year: Monitored, Evaluated, Assessed, Treated. A diagnosis on the problem list alone does not satisfy CMS RADV audit standards. Include the diagnosis in the assessment with current status and current treatment plan.
I20.0 is designated CC for MS-DRG grouping. On inpatient claims, this code can shift the DRG to the with-CC variant when documented as a present-on-admission secondary diagnosis. Hospital CDI programs flag CC opportunities during chart review. Failure to capture this code may leave 30 to 80 percent of the inpatient stay revenue unrealized.
Inclusion Terms / Approximate Synonyms
Clinical terms and conditions classified under I20.0. Per CMS ICD-10-CM Tabular 2026.
- Accelerated angina
- Crescendo angina
- De novo effort angina
- Intermediate coronary syndrome
- Preinfarction syndrome
- Worsening effort angina
Medicare Advantage HCC Impact
Capture this diagnosis annually for accurate risk adjustment. Missed HCC captures are the #1 revenue leak in Medicare Advantage risk programs.
Inpatient DRG Impact, CC
codes Unstable angina. As a Complication/Comorbidity (CC), this contributes to DRG severity adjustment when documented alongside the principal diagnosis.
Medicare LCD Coverage for I20.0
Local Coverage Determinations (LCDs) from CMS MACs that list I20.0 as a covered diagnosis.
Showing top 10 of 789 total . Click a CPT for full coverage scope.
Commercial Payer Coverage
Coverage policies from major commercial payers referencing I20.0.
3 Aetna
4 Cigna
5 Medicare
CPT Codes Commonly Billed with I20.0
Procedures frequently paired with this diagnosis based on PayerReady's Dx↔Px linkage data.
- 93015 Stress test — chest pain, palpitations, syncope, known CAD Cardiovascular Disease
- 93458 Left heart catheterization — CAD, ACS, chest pain Cardiovascular Disease
- 93451 Right heart cath — CAD, native vessel disease, ischemic cardiomyopathy, unstable angina, MI, heart failure, valvular disease, chest pain Cardiology
- 93452 Left heart cath — same as right heart cath indications Cardiology
- 93458 Coronary angiography — CAD, unstable angina, MI, heart failure, chest pain, prior bypass graft evaluation Cardiology
- 92928 PCI with stent — CAD native vessel, unstable angina, STEMI/NSTEMI all arteries, ischemic cardiomyopathy, bypass graft disease Interventional Cardiology
- 83880 CMS LCD: Billing and Coding: B-type Natriuretic Peptide (BNP) Testing CMS LCD
- 92979 CMS LCD: Billing and Coding: Percutaneous Coronary Interventions CMS LCD
- C9607 CMS LCD: Billing and Coding: Percutaneous Coronary Interventions CMS LCD
- C9600 CMS LCD: Billing and Coding: Percutaneous Coronary Interventions CMS LCD
Convert I20.0 to ICD-9-CM
Per CMS General Equivalence Mappings (GEMs), useful for legacy data review and historical claim analysis.
| ICD-10 | ICD-9 | Mapping Flags |
|---|---|---|
| I20.0 | 4111 | 10000 |
Flags format (5 digits): Approximate · No Map · Combination · Scenario · Choice List. Source: CMS 2017 GEMs (final version).
Codes Adjacent To I20.0
Other codes in section I20-I25 (Ischemic heart diseases).
ICD-10 I20.0, Billing FAQ
Is ICD-10 code I20.0 billable? +
Yes, I20.0 is a billable ICD-10-CM code that can appear as a primary or secondary diagnosis on claims.
What other names or terms map to I20.0? +
ICD-10 I20.0 includes: Accelerated angina; Crescendo angina; De novo effort angina, and 3 more clinical synonyms.
Does I20.0 affect Medicare Advantage HCC risk adjustment? +
Yes. I20.0 maps to CMS-HCC v28 category 87. Capture this diagnosis annually for accurate Medicare Advantage risk score.
Is I20.0 a CC or MCC for inpatient DRG? +
Yes, this code is designated as CC. Documenting as a secondary diagnosis on inpatient claims can shift the DRG to a higher-weighted category.
What CPT codes are commonly billed with I20.0? +
Procedures frequently paired with I20.0 include: 93015, 93458, 93451, 93452, 93458.
What ICD-9 codes does I20.0 map to? +
Per CMS GEMs, I20.0 maps to ICD-9 codes: 4111. Useful for legacy data review and historical claim analysis.
Get the full PayerReady toolkit
Free access to CPT/ICD-10 lookup, denial appeals, fee comparator, and claim auditing with credentialing enrollment.
Start free →Run this code through our claim audit tool
Check NCCI bundling, MUE limits, and modifier logic before submission.
Try the auditor →Did this page help?
Quick signal so we know what to improve.
If you want a code reference page that doesn't exist yet, email coding@payerready.com.
Tell us what's missing or wrong: coding@payerready.com. We respond within 5 business days.
Reviewed by the PayerReady Medical Coding Team
Verified against the CMS 2026 code set on May 31, 2026.
Powered by 11K CPT · 98K ICD-10 · 860K MPFS rates · 4.5M NCCI edits · 9.5M NPIs. Our data methodology · About our coding team