ICD-10-CM implementation brought several significant changes to the OCG (Official Guidelines for Coding and Reporting) with regard to Chapter 9 (Diseases of the Circulatory System) I.C.9.e Acute myocardial infarction (AMI). Preparing yourself for coding updates based on MI type is not sufficient. You also must learn how to apply these new codes using OGC for Coding and Reporting.
Here’s how the guidelines update for 2018:
- Codes from between I21.0 – (ST elevation (STEMI) myocardial infarction of anterior wall) – I21.2 – (ST elevation (STEMI) myocardial infarction of other sites), as well as I21.3 (ST elevation (STEMI) myocardial infarction of unspecified site), are for Type 1 STEMI heart attacks. Code I21.4 (Non -ST elevation (NSTEMI) myocardial infarction) captures a Type 1 NSTEMI heart attack and nontransmural heart attack. [I.C.9.e.1]
- If a patient has a Type 1 NSTEMI and it evolves into a STEMI, code it as a STEMI. If a Type 1 STEMI converts to an NSTEMI due to thrombolytic therapy, code it as a STEMI. [I.C.9.e.1]
- Code I21.3 for a heart attack documented as a Type 1 STEMI or a transmural heart attack of unspecified site. [I.C.9.e.2]
- Codes between I21.1 – (ST elevation (STEMI) myocardial infarction of inferior wall) and I21.4 are only for type 1 heart attack. [I.C.9.e.5]
- Code I21.A1 (Myocardial infarction type 2) along with a second code for the underlying cause of the demand ischemia or ischemic imbalance for a type 2 heart attack. Sequence the two codes according to the focus of care. Use I21.A1 whether the Type 2 heart attack is described as STEMI or NSTEMI. Do not use I24.8 (Other forms of acute ischemic heart disease) to capture demand ischemia in these scenarios. [I.C.9.e.5]
- Use I21.A9 (Other myocardial infarction types) for type 3, 4a, 4b, 4c, and 5 heart attacks. Follow tabular instruction contained in “code also” and “code first” notes for associated complications, and for postprocedural myocardial infarctions during or following cardiac surgery. [I.C.9.e.5]
- Codes in the I22. – Category (Subsequent ST elevation (STEMI) and non-ST elevation (NSTEMI) myocardial infarction) should not be used for myocardial infarctions other than type 1 or unspecified. For subsequent type 2 heart attacks, assign only I21.A1. For subsequent type 4 or type 5 heart attacks, assign only I21.A9. [I.C.9.e.4]
If you have been coding inpatient records since the implementation of ICD-10-CM, you may have noticed that the OCG for Subsequent acute myocardial infarctions has been evolving. For codes, effective October 1, 2018, additions were made to this guideline referring to Type 2 myocardial infarctions for the first time.
The codes for Type 2 myocardial infarctions, Subcategory I21. The Other type of myocardial infarction, were new codes as of October 1, 2018. Prior to this, there were no unique codes for Type 2 myocardial infarctions. With new codes, new or revised guidelines or clarifications often follow.
It becomes very essential to thoroughly review the 2018 OGs. It’s the only way to be sure you’re using the new codes correctly. Spending a little time on the OGs now will save your practice from costly denials and hours of rework in the future.
Source: 2018 ICD-10 CM and GEMs