MDS Alert

You need three pieces of knowledge to select an accurate code for an MI.

When reporting a myocardial infarction (MI), you must know the exact type of MI, as well as its age and location.

Try your ICD-10-CM knowledge with this quiz.

Understand MI

Question 1: What is a myocardial infarction (MI)?

Answer: A myocardial infarction (MI) is a heart attack, explains Rebecca Sanzone, CPC, CPMA, quality assurance specialist at St. Vincent Medical Group/Ascension Health and coding consultant at the American College of Cardiology. During an MI, a portion of the person’s heart is deprived of oxygen due to a blockage of a coronary artery.

Choose Between These Options for STEMIs

Question 2: A resident’s medical record shows a type I ST elevation myocardial infarction (STEMI). Which ICD-10-CM code should I report for this condition?

Answer: You have several codes to choose from for a STEMI. They are as follows:

• I21.01 (ST elevation (STEMI) myocardial infarction involving left main coronary artery)-I21.09 (ST elevation (STEMI) myocardial infarction involving other coronary artery of anterior wall)
• I21.11 (ST elevation (STEMI) myocardial infarction involving right coronary artery) and I21.19 (ST elevation (STEMI) myocardial infarction involving other coronary artery of inferior wall)
• I21.21 (ST elevation (STEMI) myocardial infarction involving left circumflex coronary artery) and I21.29 (ST elevation (STEMI) myocardial infarction involving other sites)
• I21.3 (ST elevation (STEMI) myocardial infarction of unspecified site)

Don’t miss: A STEMI is also known as a transmural acute MI, Sanzone says. The electrocardiogram (ECG) will show ST elevation and Q waves.

“The ST segment on an EKG will elevate when a patient experiences an acute MI. A STEMI usually indicates a total blockage in the heart,” says Robin Peterson, CPC, CPMA, manager of professional coding services, Pinnacle Integrated Coding Solutions LLC in Centennial, Colorado. “Another term used is ‘transmural’ meaning there is ‘full-thickness’ damage to the myocardium. A NSTEMI is generally caused by a partial blockage, and the condition may not present as acutely. The patient may be observed for a period with serial EKGs and lab tests looking at the [person’s] troponin levels before it’s ruled as an acute MI.”

Different types of STEMI sites include anterior, posterior, inferior, lateral, and septal. A resident’s physician may treat a STEMI with thrombolysis using tissue plasminogen activator (tPA) administered intravenously, percutaneous transluminal coronary angioplasty (PTCA) with or without stent placement, and coronary artery bypass graft (CABG).

Rely on Singular Code for NSTEMIs

Question 3: Which code should I report if a resident has documented a type 1 non-ST elevation myocardial infarction (NSTEMI) or a nontransmural myocardial infarction?

Answer: If your cardiologist documents NSTEMI, you should report I21.4 (Non-ST elevation (NSTEMI) myocardial infarction).

Don’t miss: If your cardiologist documents that the patient’s type 1 NSTEMI evolves to a STEMI, you should report the appropriate STEMI code, per the ICD-10-CM Official Guidelines for Coding and Reporting. However, if a type 1 STEMI converts to a NSTEMI because of thrombolytic therapy, you should report this condition with a STEMI code.

An NSTEMI is also referred to as a subendocardial acute MI, non-transmural MI, or a non-Q wave MI. In fact, you will see these as included conditions for code I21.4. The ECG for an NSTEMI will show ST depression.

Include the ‘Age’ of the MI

Question 4: Why does the age of the MI matter?

Answer: The age of the MI matters because you will report different codes based upon this information.

For example, if the MI is equal to or less than four weeks old and it meets ICD-10’s definition of “other diagnoses,” you should report the appropriate code from category I21-. This includes “transfers to another acute setting or a postacute setting,” per the guidelines.

However, if the encounter occurs after the four-week timeframe, and the patient is still receiving care related to the MI, you should report the appropriate aftercare code instead of a code from category I21-.

If the patient has an old or healed MI that doesn’t require further care, you can report I25.2 (Old myocardial infarction).

Do This for a Resident With a Type 2 MI

Question 5: How should I report type 2 MIs?

Answer: You should report type 2 MIs, which are due to demand ischemia or secondary to ischemic imbalance, with code I21.A1 (Myocardial infarction type 2). In ICD-10 coding, you should always code the underlying cause first. You should never report I24.8 (Other forms of acute ischemic heart disease) for the demand ischemia, per the guidelines.

“If a type 2 AMI is described as NSTEMI or STEMI, only assign code I21.A1,” according to the guidelines.

Beware Important Documentation Details

Question 6: What are some details I should look for in the documentation when reporting MIs?

Answer: You must know if the episode you are reporting for is “initial” or “subsequent” as well as the “duration,” Sanzone says. You must also know the location and type of MI.

“It is very important that providers know the coding rules, so they give you the information you need to specifically code the location, type, duration, timing, etc.,” she adds.