Diagnostic Coding Guidelines For Myocardial Infarction

by | Published on Sep 1, 2021 | Medical Coding

Myocardial Infarction
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Regarded as a life-threatening condition, myocardial infarction (MI) or acute myocardial infarction (AMI) occurs due to sudden blockage of blood flow to the heart, causing tissue damage. According to the National Heart, Lung, and Blood Institute, if an area of the heart muscle goes too long without blood flow and is not immediately restored, that area starts to die. Without adequate blood flow, the heart muscles get deprived of essential nutrients and oxygen that are needed to function properly. Also called heart attack, acute coronary syndrome, coronary thrombosis, the condition is usually the result of a blockage in one or more of the coronary arteries. In most cases, a blockage can develop due to a buildup of plaque, a substance mostly made of fat, cholesterol, and cellular waste products. A minor tear in the plaque triggers blood platelets and other substances to form a clot that blocks the flow of blood to the heart. Irreversible damage begins within 30 minutes of blockage. If left untreated, the condition can be fatal causing severe complications like – abnormal heart rhythms (arrhythmias), heart failure and even sudden cardiac arrest. Treatment modalities for this have improved dramatically over the years. Billing and coding for these types of severe cardiology conditions can be complex. By utilizing medical billing services in USA from a reliable provider, healthcare practices can ensure correct and timely medical billing and claims submission.

Reports from the Centers for Disease Control and Prevention (CDC) suggest that heart disease is the leading cause of death in the United States. A myocardial infarction occurs about every 40 seconds in the country. Ever year, about 805,000 Americans experience a heart attack. Of these, 605,000 people have a first heart attack, and 200,000 people have already had a heart attack. It is estimated that about 1 in 5 heart attacks are silent, meaning the damage is done, but the person is not aware of it.

A spasm of a coronary artery that shuts down blood flow to part of the heart muscle is another cause of a heart attack. Aging, obesity, usage of tobacco and illicit drugs, a family history of heart attacks and other lifestyle diseases can increase the risk of this condition. In addition, infection with COVID-19 also may damage the heart in ways that result in a heart attack.

What Are The Symptoms Of Myocardial Infarction (MI)?

Chest pain and heart attack are the classic symptoms of myocardial infarction. The symptoms can vary from person to person and depend on the severity of the condition. It is important to note that not all people who have heart attacks experience the same symptoms or the same severity of symptoms. In fact, women are slightly more likely than men to report unusual symptoms. Some of the common symptoms of a heart attack include –

  • Pressure or tightness in the chest
  • Sweating
  • Shortness of breath
  • Pain in the chest, back, jaw, and other areas of the upper body (that lasts more than a few minutes or that goes away and comes back)
  • Nausea and vomiting
  • Dizziness
  • A fast heart rate

ICD- 10 Codes For Diagnosing And Coding AMI

Initial diagnosis of myocardial infarction (MI) involves a physical examination where in the cardiologists will check for irregularities in the heartbeat. The level of blood pressure, pulse and temperature will be checked. Patients will be connected to a heart monitor and tests like – electrocardiogram (EKG to measure heart’s electrical activity) and blood tests will be performed to check whether they are having the symptoms of a heart attack. Other additional diagnostic tests like – stress test, echocardiogram, chest X-ray, coronary catheterization (angiogram) and cardiac CT or MRI may also be performed as part of the diagnosis. Treatment options for MI include a combination of medications and surgical procedures. Surgical and other procedures include – coronary angioplasty and stenting and coronary artery bypass surgery. Certain healthcare practices offers cardiac rehabilitation programs that generally focus on four main areas — medications, lifestyle changes, emotional issues and a gradual return to a patients normal level of activities.

Types of AMI

Generally, there are different types of myocardial infarctions with several underlying causes. Identifying and diagnosing the specific type of MI as early as possible will help in determining the most appropriate treatment options. The different types of MI include –

  • Type 1 (spontaneous MI related to ischemia)
  • Type 2 (MI secondary to an ischemic imbalance)
  • Type 3 (MI resulting in death due to unavailable biomarker values)
  • Type 4a (MI associated with percutaneous coronary intervention [PCI])
  • Type 4b (MI associated with in-stent thrombosis)
  • Type 4c (MI associated with restenosis of coronary artery after previous percutaneous coronary intervention [PCI])
  • Type 5 (MI associated with coronary artery bypass graft [CABG])

ICD-10 – CM-Coding

In ICD-10, there are quite a few coding guidelines pertaining to the circulatory system and acute myocardial infarctions that we need to know in order to code for it accurately. However, having a basic knowledge of the condition – including the different terms used to describe it, as well as the causes, symptoms, and diagnosis is an important aspect. In ICD-10-CM, codes for acute myocardial infarction are located in Chapter 9 -Diseases of the Circulatory System (I00-I99) under Ischemic Heart Diseases (I20-I25). The documentation should provide the site (wall) of the AMI, arteries affected, whether it is initial or subsequent, and the type of AMI.

Acute MI – An acute MI is a myocardial infarction specified as acute or with a stated duration of 4 weeks (28 days) or less from onset. Acute MI codes from category I21 include –

  • I21 Acute myocardial infarction
  • I21.0 ST elevation (STEMI) myocardial infarction of anterior wall
    • I21.01 ST elevation (STEMI) myocardial infarction involving left main coronary artery
    • I21.02 ST elevation (STEMI) myocardial infarction involving left anterior descending coronary artery
    • I21.09 ST elevation (STEMI) myocardial infarction involving other coronary artery of anterior wall
  • I21.1 ST elevation (STEMI) myocardial infarction of inferior wall
    • I21.11 ST elevation (STEMI) myocardial infarction involving right coronary artery
    • I21.19 ST elevation (STEMI) myocardial infarction involving other coronary artery of inferior wall
  • I21.2 ST elevation (STEMI) myocardial infarction of other sites
    • I21.21 ST elevation (STEMI) myocardial infarction involving left circumflex coronary artery
    • I21.29 ST elevation (STEMI) myocardial infarction involving other sites
  • I21.3 ST elevation (STEMI) myocardial infarction of unspecified site
  • I21.4 Non-ST elevation (NSTEMI) myocardial infarction
  • I21.9 Acute myocardial infarction, unspecified
  • I21.A Other type of myocardial infarction
    • I21.A1 Myocardial infarction type 2
    • I21.A9 Other myocardial infarction type

Understanding The Difference Between STEMI and NSTEMI

Regarded as the most serious type of MI, an ST elevation myocardial infarction (STEMI) is caused by a sudden and long-term blockage of blood supply. Also called a Q-wave or transmural myocardial infarction, in this condition a large area of the heart muscle is damaged due to the blockage and an elevation of the ST segment on the electrocardiogram (ECG) occurs. On the other hand, a Non-ST elevation myocardial infarction (NSTEMI) is caused by a partial or temporary blockage. Also referred to as a non-Q wave or non-transmural MI, in this condition, the extent of the damage to the heart muscle may be relatively small based on the blood supplied by the affected artery.

Subsequent MI – This is an acute myocardial infarction occurring within 4 weeks (28 days) of a previous acute myocardial infarction, regardless of site. Subsequent MI codes from category I22 include –

  • I22 Subsequent ST elevation (STEMI) and non-ST elevation (NSTEMI) myocardial infarction
  • I22.0 Subsequent ST elevation (STEMI) myocardial infarction of anterior wall
  • I22.1 Subsequent ST elevation (STEMI) myocardial infarction of inferior wall
  • I22.2 Subsequent non-ST elevation (NSTEMI) myocardial infarction
  • I22.8 Subsequent ST elevation (STEMI) myocardial infarction of other sites
  • I22.9 Subsequent ST elevation (STEMI) myocardial infarction of unspecified site

Use Additional Codes

The “Use additional” note provided at category I21 and category I22 indicates the following should be coded, if applicable –

  • Exposure to environmental tobacco smoke (Z77.22)
  • History of tobacco dependence (Z87.891)
  • Occupational exposure to environmental tobacco smoke (Z57.31)
  • Status post administration of tPA (rtPA) in a different facility within the last 24 hours prior to admission to current facility (Z92.82)
  • Tobacco dependence (F17.-)
  • Tobacco use (Z72.0)
  • Presence of hypertension (I10-I16)

The ICD-10-CM codes for myocardial infarction (MI) identify the site of the AMI, arteries affected, whether AMI temporal parameter is (initial or subsequent), and whether the MI is an ST elevation or non-ST elevation infarction. With accurate and comprehensive documentation, medical coders can determine the correct codes and the appropriate sequencing of ICD-10 codes to ensure efficient medical billing and coding. To ensure maximum accuracy and efficiency in medical billing and coding tasks, healthcare practices can depend on the services of a reputable cardiology medical billing company.

Natalie Tornese

Holding a CPC certification from the American Academy of Professional Coders (AAPC), Natalie is a seasoned professional actively managing medical billing, medical coding, verification, and authorization services at OSI.

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