Excludes1 pair

I5A vs S26-

I5A and S26 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
injury of heart (S26.-)
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)
S26

Injury of heart

Not billable
Chapter 19
Injury, poisoning and certain other consequences of external causes
Section
S20-S29

These two codes sit in different chapters of the Tabular List, which is usually the clearest signal that they describe different underlying processes rather than different degrees of the same one.

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