Go to content

ICD-10 Articles: Coding Corner

Coding for Acute Myocardial Infarction (AMI)

When one compares ICD-9 to ICD-10, differences in definitions and reporting parameters exist. The time frame for the reporting of an acute myocardial infarction differs between the two code sets as well as the definition of “subsequent”.

In ICD-9-CM, AMI codes are assigned based on the episode of care, either initial or subsequent. The initial episode of care is designated for a newly diagnosed myocardial infarction. The concept of subsequent refers to a subsequent episode of care for an acute myocardial infarction which includes encounters when the patient is admitted for further observation, evaluation, or treatment for a myocardial infarction that has received initial treatment, but is still less than eight weeks old.

In contrast, the concept of subsequent has changed in ICD-10. For encounters occurring while the AMI is equal to, or less than, four weeks old and the patient requires continued care for the myocardial infarction, codes for the AMI may still be reported. If the patient suffers a new AMI during the four week time frame following the initial AMI, regardless of site, a subsequent code (category I22) is assigned in conjunction with a code from category I21.

Additional information about coding for acute myocardial infarctions may be found in coding guideline I.C.9.e – Acute Myocardial infarction (AMI).