ICD-10 Code I20.0 – Unstable angina (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code I20.0 – Unstable angina
What it is
Use this code for angina that is newly occurring, worsening, or occurring at rest and is considered unstable. It reflects reduced coronary blood flow with an acute change in the usual chest pain pattern.
Clinical signs
Typical documentation includes chest pressure or pain that is more frequent, more severe, or less predictable than before. Clinical features vary; refer to documentation.
When to use this code
Assign I20.0 when the provider documents unstable angina, crescendo angina, or angina at rest without evidence of myocardial infarction. Use it for encounters where the diagnosis is confirmed or treated as the reason for care.
If the record instead describes a different angina type or an acute coronary syndrome with infarction, choose the more specific documented diagnosis. Check documentation when the wording is unclear.
Do not use for
Do not use this code for stable angina or angina documented only as unspecified. Do not use it when myocardial infarction is documented.
Coding tip
Look for provider wording such as “unstable,” “crescendo,” or “at rest” before assigning I20.0.