Convert ICD-10-CM I21.9 to ICD-9-CM

ICD-10-CM I21.9 converts approximately to:

2015 ICD-9-CM 410.90 Acute myocardial infarction of unspecified site, episode of care unspecified
or:
2015 ICD-9-CM 410.91 Acute myocardial infarction of unspecified site, initial episode of care
or:
2015 ICD-9-CM 410.92 Acute myocardial infarction of unspecified site, subsequent episode of care

Note: approximate conversions between ICD-9-CM codes and ICD-10-CM codes may require clinical interpretation in order to determine the most appropriate conversion code(s) for your specific coding situation.

Source: 2021 ICD-10-CM CMS General Equivalence Mappings.