ED Coding and Reimbursement Alert

Do you know what type of MI indicates sudden cardiac death?

When a patient reports to the emergency department (ED) with symptoms of a myocardial infarction (MI), coders need to be ready to recognize all the major types of MI.

There are a few MI ICD-10-CM codes that will be used frequently in your ED. Knowing how to choose the correct code for each patient is paramount to getting the diagnoses right and the claim paid.

Read on to learn more about how to recognize the major types of MIs and understand how to choose the appropriate ICD-10-CM code for each patient.

Know STEMI, NSTEMI Differences

There are two main categories for an MI, ST-elevated myocardial infarction (STEMI) and non-ST-elevated myocardial infarction (NSTEMI). A STEMI has a higher risk of mortality and morbidity in patients when delayed treatment occurs. It has been found that when a STEMI is treated with percutaneous coronary intervention (PCI) within 90 minutes of presenting to the ED, the chance of mortality decreases significantly.

In situations where PCI is not possible within the first 90-120 minutes of the MI occurring, the American College of Cardiology Foundation (ACCF) and the American Heart Association (AHA) recommend that PCI should be performed in patients with a STEMI within 12 hours of detection.

AHA NSTEMI guidelines state that immediate PCI should only be used when a patient is hemodynamically unstable or has ongoing ischemia after optimal medical therapy within 24 hours for those patients with a moderate- to high-risk NSTEMI. Both STEMI and NSTEMI types are broken down into the five MI subclassifications.

Identify 5 MI Types

There are five main types of MI; you’ll code for most of them using only a few codes, but it’s a good idea to know all the MI types ahead of time:

• Type 1 MI: The most common MI diagnosis, this type is caused by atherosclerotic plaque rupture or ulceration, resulting in in either occlusive or non-occlusive intraluminal thrombosis. Diagnosis code subcategory I21.- (Acute myocardial infarction) will be where you find your type 1 MI codes, including those for STEMI and NSTEMI MIs. Category I21.- can also be broken down into subcategories for the artery/wall involved.

• Type 2 MI: This MI type is caused by a mismatch of myocardial oxygen supply and demand. Acute plaque rupture is not the cause of this type of MI. This type requires both a myocardial injury and one of the following: angina, ischemic changes from electrocardiogram (EKG) monitoring, or other imaging that suggests new myocardial loss. Report type 2 MIs with I21.A1 (Myocardial infarction type 2). Per ICD-10-CM guidelines, you should code the underlying cause of the MI first, if it’s known.

• Type 3 MI: Per ICD-10-CM, “A Type 3 myocardial infarction is sudden cardiac death.” This MI type has typical signs/symptoms of an MI with ischemic changes and ventricular fibrillation with an outcome of sudden cardiac death. Report type 3 MIs with I21.A9 (Other myocardial infarction type). Code first the post-procedural MI, if applicable, and/or code also any complication, if known. If acute plaque rupture is found upon autopsy, this code would change back to a type 1 MI diagnosis code.

• Type 4 MI: Per ICD-10-CM, “A Type 4a-4c myocardial infarction is one related to percutaneous coronary intervention (PCI).”  This type occurs in patients who receive a revascularization procedure and is broken down into three sub-classifications: 4a (PCI-related MI), 4b (In-stent thrombosis-related MI), and 4c (In-stent restenosis-related MI). Diagnosis code I21.A9 is also reported for these types of MIs (code first post-procedural MI, if applicable, and/or code also any complication, if known).

• Type 5 MI: Per ICD-10-CM, “A Type 5 myocardial infarction is related to coronary artery bypass grafting (CABG).” This MI occurs either intraoperatively or postoperatively related to a CABG. Diagnosis code I21.A9 is also coded for this type of MI (code first post-procedural MI, if applicable, and/or code also any complication, if known).

There are other MI types in the ICD-10-CM code book, but the MIs listed above are the most common.

Use These Codes for Complications Following MI

When a patient suffers a STEMI or NSTEMI MI, certain current complications might also occur. You must document the issue as a current complication following an acute MI. You’ll report current MI complications with codes in the I23.0 (Hemopericardium as current complication following acute myocardial infarction) through I23.8 (Other current complications following acute myocardial infarction) subcategory.

Consider This Clinical Example

A patient present to the ED with ongoing chest pain and shortness of breath consistent with acute coronary syndrome (ACS). The ED provider runs several tests including troponin, complete blood count (CBC), C-reactive protein (CRP), and EKG. The CRP was abnormal, and the EKG showed ST elevations, which determined the definitive diagnosis as a STEMI. The patient is considered high-risk due to having hypertension with chronic systolic congestive heart failure. Both aspirin and prasugrel are given to help prevent an atherothrombotic event.

The ED physician then calls in a cardiologist to evaluate, consult, and perform emergent heart catheterization with PCI of the culprit vessel. The ED provider has a discussion of management and treatment of the patient, and the cardiologist confirms this is an MI involving the anterior wall of the left anterior descending artery. The patient is admitted to inpatient status and care is transferred to the hospitalist and cardiologist for continued management.

For the ED physician’s services, you’d report 99285 (Emergency department visit for the evaluation and management of a patient, which requires a medically appropriate history and/or examination and high level of medical decision making). Also, append I21.02 (ST elevation (STEMI) myocardial infarction involving left anterior descending coronary artery), I11.0 (Hypertensive heart disease with heart failure), and I50.22 (Chronic systolic (congestive) heart failure) to 99285.

Cristin Robinson, CPC, CPMA, CCC, CRC, CEMC, AAPC Approved Instructor,
Education Coding Consultant, Bristol, Tennessee