Excludes1 pair
I23.1 vs I51.0
I23.1 and I51.0 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 I23.1
acquired atrial septal defect not specified as current complication following acute myocardial infarction (I51.0)
I23.1
Atrial septal defect as current complication following acute myocardial infarction
Billable
- Chapter 9
- Diseases of the circulatory system
- Section
- I20-I25
Indexed under
- Defect, defective › atrial septal › following acute myocardial infarction (current complication)
- Defect, defective › septal NOS › atrial › following acute myocardial infarction (current complication)
- Complication › following › acute myocardial infarction NEC › atrial › septal defect
- Complication › following › acute myocardial infarction NEC › defect › septal › atrial (heart)
I51.0
Cardiac septal defect, acquired
Billable
- Chapter 9
- Diseases of the circulatory system
- Section
- I30-I5A
Use when the record says
- Acquired septal atrial defect (old)
- Acquired septal auricular defect (old)
- Acquired septal ventricular defect (old)
Indexed under
- Defect, defective › septal NOS › acquired (atrial) (auricular) (ventricular) (old)
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