Unstable Angina ICD-10 Code: I20.0

Last updated: August 28, 2026

Quick Answer

The ICD-10 code for unstable angina is I20.0, which includes accelerated, crescendo, and de novo effort angina. Critical rule: when the patient also has documented coronary artery disease of a native artery, use the combination code I25.110 instead of coding I25.10 and I20.0 separately.

Primary Code Details

Code	Description	Billable
I20.0	Unstable angina	Yes

Related Codes

Code	Description	Billable
I25.110	Atherosclerotic heart disease of native coronary artery with unstable angina pectoris	Yes
I20.9	Angina pectoris, unspecified	Yes
I20.2	Refractory angina pectoris	Yes
I20.81	Angina pectoris with coronary microvascular dysfunction	Yes
I21.4	Non-ST elevation (NSTEMI) myocardial infarction	Yes

Documentation Requirements

Document the unstable pattern: rest angina, new-onset, or accelerating/crescendo symptoms
Note whether coronary artery disease is established and in which vessels (native vs graft)
Document troponin results - positive troponin shifts the diagnosis toward NSTEMI (I21.4)
Record whether angina is refractory to therapy (I20.2) if applicable

Common Coding Scenarios

Unstable Angina with Known CAD

Documentation:

"Patient with known native-vessel CAD presents with rest angina, troponins negative."

Code:

I25.110 - Atherosclerotic heart disease of native coronary artery with unstable angina pectoris

Rationale:

ICD-10-CM presumes a causal relationship between CAD and angina. The combination code I25.110 replaces separate coding of I25.10 + I20.0.

Accelerated Angina, No Documented CAD

Documentation:

"Increasing frequency and severity of exertional chest pain over one week; no prior CAD diagnosis. Troponins negative."

Code:

I20.0 - Unstable angina

Rationale:

Accelerated/crescendo angina is an inclusion term under I20.0. Without established CAD, I20.0 stands alone.

Rest Angina with Positive Troponin

Documentation:

"Rest chest pain with troponin rise and fall, no ST elevation. Diagnosed NSTEMI."

Code:

I21.4 - Non-ST elevation (NSTEMI) myocardial infarction

Rationale:

Myocardial injury with the acute coronary syndrome picture is coded as NSTEMI, not unstable angina. The two are mutually exclusive diagnoses.

Frequently Asked Questions

What is the ICD-10 code for unstable angina?

I20.0. It includes accelerated angina, crescendo angina, de novo effort angina, and intermediate coronary syndrome. It is billable when no causal CAD combination code applies.

When do I use I25.110 instead of I20.0?

When the patient has documented atherosclerotic heart disease of a native coronary artery, ICD-10-CM presumes causality and requires the combination code I25.110 (CAD with unstable angina) rather than two separate codes.

What is the code for accelerated angina pectoris?

Accelerated angina is an inclusion term under I20.0 (Unstable angina). With documented native-artery CAD, it rolls into the combination code I25.110.

Related Resources

Last updated: August 2026. Code data reflects ICD-10-CM 2026 version. This guide is for educational purposes only. Always verify codes against current official guidelines.