I20.0

HCC Category Mapping

What This Code Means

Chest pain or discomfort caused by reduced blood flow to the heart that occurs unpredictably, including at rest or with minimal exertion.

Coding Tips

• •Unstable angina is a form of acute coronary syndrome; ensure appropriate cardiac workup and troponin testing are documented
• •Do not assign this code if troponin levels are elevated; use acute MI codes instead

Clinical Significance

Unstable angina is an acute coronary syndrome characterized by new-onset, accelerating, or rest angina without evidence of myocardial necrosis (negative troponins). It represents a high-risk condition with imminent threat of myocardial infarction and requires urgent evaluation and intervention. This carries significant risk adjustment weight reflecting the acute cardiac morbidity and resource intensity.

Documentation Requirements

• ✓Provider diagnosis explicitly stating unstable angina
• ✓Clinical presentation: new onset, crescendo, or rest angina
• ✓Negative cardiac biomarkers (troponin) — if positive, this becomes NSTEMI, not unstable angina
• ✓ECG findings documented (may show ST depression, T-wave inversion, or be normal)
• ✓Risk stratification (TIMI score, HEART score) if documented
• ✓Treatment plan including antiplatelet therapy, anticoagulation, and consideration for cardiac catheterization
• ✓Coronary angiography findings if performed
• ✓Documentation distinguishing from stable angina and NSTEMI

Commonly Confused Codes