I21.4

HCC Category Mapping

What This Code Means

A heart attack where the blood supply to the heart is blocked but without the characteristic ST segment elevation on an EKG, typically involving partial blockage or smaller vessel occlusion.

Coding Tips

• •NSTEMI is confirmed by elevated cardiac biomarkers (troponin) without ST elevation on EKG
• •Assign the appropriate 7th character for timing; NSTEMI codes do not specify the culprit vessel location

Clinical Significance

Non-ST elevation myocardial infarction is the most common type of acute coronary syndrome, characterized by cardiac biomarker elevation without persistent ST elevation on electrocardiogram. It represents partial or transient coronary artery occlusion and carries significant short-term and long-term morbidity. Accurate capture is critical as it maps to the highest ischemic heart disease HCC category.

Documentation Requirements

• ✓Explicit documentation of Non-ST elevation myocardial infarction or NSTEMI diagnosis
• ✓Elevated cardiac biomarkers (troponin) with clinical context
• ✓Electrocardiogram findings showing absence of persistent ST elevation (may show ST depression, T-wave inversion, or be normal)
• ✓Clinical symptoms consistent with acute coronary syndrome
• ✓Treatment plan including anticoagulation, antiplatelet therapy, and consideration for cardiac catheterization
• ✓Timing within the 4-week acute window

Commonly Confused Codes