Excludes1 pair
I21- vs I5A
I21 and I5A are not coded together. ICD-10-CM declares them mutually exclusive with an Excludes1 note — the two conditions are not expected to occur together, so exactly one of them is normally correct for a given encounter. The Official Guidelines carve out one exception: if the two conditions are clearly unrelated to each other, both may be reported.
The official note, declared on I5A
acute myocardial infarction (I21.-)
I21
Acute myocardial infarction
Not billable
- Chapter 9
- Diseases of the circulatory system
- Section
- I20-I25
Use when the record says
- cardiac infarction
- coronary (artery) embolism
- coronary (artery) occlusion
- coronary (artery) rupture
- coronary (artery) thrombosis
- infarction of heart, myocardium, or ventricle
- myocardial infarction specified as acute or with a stated duration of 4 weeks (28 days) or less from onset
I5A
Non-ischemic myocardial injury (non-traumatic)
Billable
- Chapter 9
- Diseases of the circulatory system
- Section
- I30-I5A
Use when the record says
- Acute (non-ischemic) myocardial injury
- Chronic (non-ischemic) myocardial injury
- Unspecified (non-ischemic) myocardial injury
Indexed under
- Neurogenic stunned myocardium
- Stunned myocardium, neurogenic
- Injury › myocardial (acute) (chronic) (non-ischemic) (non-traumatic)
- Injury › heart › non-traumatic (acute) (chronic) (non-ischemic)
Excludes1 is not always absolute: where two conditions covered by the note are genuinely unrelated, CMS guidance permits reporting both. Document the reasoning rather than assuming it. More on Excludes1 vs Excludes2 · FY2027