I21.B
BillableMyocardial infarction with coronary microvascular dysfunction
HCC Category Mapping
V28HCC 228 — Acute Myocardial Infarction
0.000V24HCC 86 — Acute Myocardial Infarction
0.274ESRDHCC 86 — Acute Myocardial Infarction
0.000RxHCCHCC 188 — Coronary Artery Disease and Angina
0.000What This Code Means
A heart attack caused by dysfunction of the smallest blood vessels in the heart rather than blockage of larger coronary arteries.
Coding Tips
- •This code requires documentation specifically mentioning coronary microvascular dysfunction or microvascular angina as the cause
- •Ensure the provider has documented this diagnosis; it may require cardiac catheterization findings to confirm
Clinical Significance
Myocardial infarction with coronary microvascular dysfunction represents a newer diagnostic entity where myocardial damage occurs due to dysfunction of the small coronary vessels rather than obstruction of epicardial arteries. This condition is more common in women and may be underdiagnosed. The creation of this specific code reflects growing recognition of microvascular disease as a significant cause of ischemic heart events.
Documentation Requirements
- ✓Explicit documentation of myocardial infarction with coronary microvascular dysfunction
- ✓Evidence of myocardial infarction (biomarker elevation, ischemic symptoms)
- ✓Cardiac catheterization showing non-obstructive coronary arteries
- ✓Microvascular function testing results (coronary flow reserve, index of microcirculatory resistance) if performed
- ✓Exclusion of epicardial coronary artery obstruction as the cause
Commonly Confused Codes
I21.4 — Non-ST elevation myocardial infarction: caused by epicardial coronary disease, not microvascularI21.A1 — Myocardial infarction type 2: caused by supply-demand mismatch, different mechanism than microvascular dysfunctionI24.81 — Acute coronary microvascular dysfunction: microvascular dysfunction without actual myocardial infarctionI20.89 — Other forms of angina pectoris: chest pain without myocardial damageI25.89 — Other forms of chronic ischemic heart disease: chronic condition, not acute myocardial infarction
Code Hierarchy
└I21Acute myocardial infarction└I21.BMyocardial infarction with coronary microvascular dysfunction
└I21.BMyocardial infarction with coronary microvascular dysfunction