Coding for Coronary Artery Disease
For The Record
Vol. 18 No. 10 P. 41

The most prevalent type of heart disease, coronary artery disease (CAD) occurs when the coronary arteries become narrowed or blocked by plaque. Atherosclerosis is the most common cause of CAD and is characterized by a progressive buildup of plaque that restricts blood flow to the heart muscle, resulting in angina pectoris. If the blockage is complete, it leads to an acute myocardial infarction or sudden cardiac death.

The ICD-9-CM diagnosis codes for CAD are classified to subcategory 414.0x. The fifth-digit subclassification identifies the location of the disease (ie, native vessel, bypass graft) and whether it has occurred in a transplanted heart. The appropriate code assignment will depend on the documentation, and it may be appropriate to assign more than one code from subcategory 414.0.

Code 996.03, Mechanical complication due to coronary artery bypass graft, should not be assigned for a diagnosis of coronary artery graft occlusion due to atherosclerosis. A code from 414.0x should be assigned instead (AHA Coding Clinic for ICD-9-CM, 1995, second quarter, page 17).

Signs and Symptoms
Chest pain is often the first indicator of CAD. The pain may be described as pressure, tightness, heaviness, squeezing, or burning. In addition, it may radiate to the left arm (most common), left shoulder, neck, lower jaw, midback, or right arm. Pressing on the chest wall does not cause the pain. Chest pain related to CAD may be termed angina pectoris.

• Stable angina (413.9) is predictable, brought on by exertion, and diminishes after resting and nitroglycerin is administered.

• Unstable angina (411.1) is a change in the usual pattern of angina, such as being more frequent, more severe, longer lasting, and occurring at rest.

• Chest pain (786.5x) other than angina can have many other underlying causes. Chest pain that begins suddenly or lasts only a few seconds is less likely to be angina.

If after careful stud, the physician determines the patient’s underlying cause of chest pain is angina and the patient has a documented history of CAD, then CAD will be sequenced as the principal diagnosis followed by the appropriate code for the angina (AHA Coding Clinic for ICD-9-CM, 2001, third quarter, page 15).

Other CAD symptoms may include shortness of breath with exertion, fast heartbeat, weakness, dizziness, nausea, and increased perspiration.

Diagnosis
If a patient has several risk factors for CAD or exhibits any of the above symptoms, the physician may suggest one or more of the following diagnostic studies:

• electrocardiogram;

• holter monitoring (ambulatory electrocardiography monitoring);

• stress test;

• cardiac catheterization with coronary angiography;

• coronary magnetic resonance angiography;

• nuclear scan;

• echocardiogram; and

• electron beam computed tomography (also called ultrafast CT).

Treatment
Treatment for CAD depends on the extent of the disease. In some cases, it may be managed with lifestyle changes and medications. Some medications may include the following:

• cholesterol-lowering drugs, also called lipid-lowering drugs, such as statins;

• aspirin;

• beta-blockers;

• nitrates, such as nitroglycerin;

• calcium channel blockers; and

• angiotensin-converting enzyme inhibitors.

Surgical procedures that may be performed on patients with CAD include the following:

• coronary artery bypass graft (36.1x);

• transmyocardial laser revascularization (36.31 or 36.32);

• brachytherapy (92.27);

• atherectomy (00.66);

• percutaneous transluminal coronary angioplasty (PTCA, 00.66); and

• stent insertion. If a stent is inserted, assign code 36.06 or 36.07 as an additional code with the PTCA code. Small, wire-mesh tubes are inserted to keep the arteries open. Special types of stents may be utilized such as covered, coated, or drug-eluting. A covered stent (36.06) is layered with silicone or a silicone derivative such as polytetrafluoroethylene or polyurethane. A coated stent (36.06) is bonded with drugs such as heparin or layered with biocompatible substances (phosphorylcholine). A drug-eluting stent (36.07) is coated with medications that prevent the growth of cells around the stent without impairing the proper healing of the vessel, decrease inflammation, and have antibiotic properties. The stent releases the drug over a period of 30 to 45 days in a controlled manner. The benefits of drug-eluting stents include reducing the need for repeat procedures and reducing scar formation. Neither covered nor coated stents release a drug over a period of time as drug-eluting stents do (AHA Coding Clinic for ICD-9-CM, 2002, fourth quarter, pages 101-103). If coronary artery stent stenosis does occur, assign code 996.72 (AHA Coding Clinic for ICD-9-CM, 2001, third quarter, page 20).

Additional procedure codes will be assigned with the PTCA and stent insertion codes to identify the number of vessels operated on and the number of stents inserted.

The following four codes identify multiple vessel treatment:

• 00.40, Procedure on single vessel;

• 00.41, Procedure on two vessels;

• 00.42, Procedure on three vessels; and

• 00.43, Procedure on four or more vessels.

The following four codes identify multiple stent insertion:

• 00.45, Insertion of one vascular stent;

• 00.46, Insertion of two vascular stents;

• 00.47, Insertion of three vascular stents; and

• 00.48, Insertion of four or more vascular stents.

Therefore, a minimum of four procedure codes are assigned when a PTCA with stent insertion is performed:

• one code to identify the angioplasty or atherectomy (00.66);

• one code to identify the type of stent inserted (36.06 or 36.07);

• one code to identify the number of vessels (00.40-00.43); and

• one code to identify the number of stents inserted (00.45-00.48).

The following note will appear at the top of subcategory code 00.4, Adjunct vascular system procedures: “These codes can apply to both coronary and peripheral vessels. These codes are to be used in conjunction with other therapeutic procedure codes to provide additional information on the number of vessels upon which a procedure was performed and/or the number of stents inserted. As appropriate, code both the number of vessels operated on (00.40-00.43) and the number of stents inserted (00.45-00.48).”

Coding and sequencing for CAD are dependent on the physician documentation in the medical record and application of the Official Coding Guidelines for inpatient care. Also, use specific AHA Coding Clinic for ICD-9-CM and American Medical Association CPT Assistant references to ensure complete and accurate coding.

— This information was prepared by Audrey Howard, RHIA, of 3M Health Information Systems (800-367-2447), a supplier of coding and classification systems to nearly 5,000 healthcare providers. The company and its representatives do not assume any responsibility for reimbursement decisions or claims denials made by providers or payors as the result of the misuse of this coding information.

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