I21.9

Clinical notes

Documentation support

General coding-documentation guidance — not a substitute for payer-specific requirements or professional coding judgment.

• •This code describes an unspecified presentation. If the medical record documents a more specific detail (e.g. laterality, type, or affected site), a more specific sibling code should be used instead — see Related codes below.
• •As a general rule, code to the highest level of specificity supported by the documentation in the medical record.

ICD-9-CM equivalent

Informational only — GEM mappings are approximate, not guaranteed one-to-one equivalents. Verify before use in billing.

• 41090Approximate match
• 41091Approximate match
• 41092Approximate match

Associated MS-DRGs

I21.9 can serve as the principal diagnosis for these Medicare Severity Diagnosis-Related Groups.

Informational only — actual DRG assignment also depends on procedures, complications/comorbidities (CC/MCC), discharge status, and payer-specific rules not reflected here.

• DRG 205Other Respiratory System Diagnoses with MCC
• DRG 206Other Respiratory System Diagnoses without MCC
• DRG 280Acute Myocardial Infarction, Discharged Alive with MCC
• DRG 281Acute Myocardial Infarction, Discharged Alive with CC
• DRG 282Acute Myocardial Infarction, Discharged Alive without CC/MCC
• DRG 283Acute Myocardial Infarction, Expired with MCC
• DRG 284Acute Myocardial Infarction, Expired with CC
• DRG 285Acute Myocardial Infarction, Expired without CC/MCC