Excludes1 pair
I45.5 vs I45.9
I45.5 and I45.9 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 I45.5
heart block NOS (I45.9)
I45.5
Other specified heart block
BillableUnspecified
- Chapter 9
- Diseases of the circulatory system
- Section
- I30-I5A
Use when the record says
- Sinoatrial block
- Sinoauricular block
Indexed under
- Arborization block (heart)
- Arrest, arrested › sinus
- Block, blocked › arborization (heart)
- Block, blocked › nodal
- Block, blocked › sinoatrial
I45.9
Conduction disorder, unspecified
BillableUnspecified
- Chapter 9
- Diseases of the circulatory system
- Section
- I30-I5A
Use when the record says
- Heart block NOS
- Stokes-Adams syndrome
Indexed under
- Adams-Stokes disease or syndrome (-Morgagni)
- Dropped heart beats
- Morgagni-Stokes-Adams syndrome
- Spens' syndrome (syncope with heart block)
- Stokes-Adams disease or syndrome
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