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June 28, 2004

Coding for Coronary Artery Disease
Vol. 16 No. 13 p. 29

Coronary artery disease (CAD), the most prevalent type of heart disease, 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 causes less blood flow to the heart muscle, resulting in angina pectoris. If the blockage is complete, it leads to an acute myocardial infarction (AMI) 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 or not 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. The following is an explanation of what is included in each code:

• 414.00, Coronary atherosclerosis of unspecified type of vessel, native or graft: Assign this code if the documentation does not specify the disease’s location. For example, the patient has a history of a coronary artery bypass graft (CABG). The physician documents the patient has CAD but does not specify if it is of a native vessel or bypass graft ( AHA Coding Clinic for ICD-9-CM, 1997, third quarter, page 15).

• 414.01, Coronary atherosclerosis of native coronary artery: Assign this code if the documentation specifies the CAD is of a native coronary artery. Also assign this code if the patient has CAD and there is no history of prior CABG. In addition, if a patient had a prior percutaneous transluminal coronary angioplasty (PTCA) and is admitted with reocclusion of the coronary artery, code 414.01 is assigned ( AHA Coding Clinic for ICD-9-CM, 1995, second quarter, pages 17-18).

• 414.02, Coronary atherosclerosis of autologous vein bypass graft: Assign this code if the documentation specifies CAD of the patient’s own vein tissue (eg, saphenous vein graft).

• 414.03, Coronary atherosclerosis of nonautologous biological bypass graft: Assign this code if the documentation specifies CAD of a tissue graft that is not the patient’s own tissue.

• 414.04, Coronary atherosclerosis of artery bypass graft: Assign this code if the documentation specifies CAD of an internal mammary artery or other artery used as a bypass graft.

• 414.05, Coronary atherosclerosis of unspecified type of bypass graft: Assign this code if the documentation specifies CAD of a bypass graft but does not specify the type of bypass graft.

• 414.06, Coronary atherosclerosis of native coronary artery of transplanted heart.

• 414.07, Coronary atherosclerosis of bypass graft (artery, vein) of transplanted heart.
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
The signs and symptoms of CAD vary widely depending on the severity and may produce no symptoms until an AMI occurs. Chest pain is often the first indicator of CAD. The chest pain may be described as pressure, tightness, heaviness, squeezing, or burning. In addition, it may radiate to the left arm, left shoulder, neck, lower jaw, midback, or right arm.

• 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 and more severe, lasting longer, and occurring at rest.

• Chest pain (786.5x) other than angina can have many other possible underlying causes. Chest pain that begins suddenly or lasts only a few seconds is less likely to be angina.
If after careful study 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 symptoms of CAD 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 is exhibiting 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/or electron beam computerized tomography, also called ultrafast CT.

Treatment
Treatment for CAD depends on the extent of the disease. It may be able to be managed with lifestyle changes and some medications, including the following:

• Cholesterol-lowering drugs, also called lipid-lowering drugs, such as statins

• Aspirin

• Beta-blockers

• Nitrates, such as nitroglycerin

• Calcium channel blockers

• Angiotensin-converting enzyme inhibitors
Surgical procedures that may be performed on patients with CAD include the following:

• Coronary artery bypass graft (CABG; 36.1x)

• Transmyocardial laser revascularization (TMR; 36.31 or 36.32)

• Percutaneous transluminal coronary angioplasty (PTCA; 36.01, 36.02, and 36.05)

• Stent insertion — If a stent is inserted, assign code 36.06 or 36.07 as an additional code with the PTCA code. A covered or coated stent is classified to 36.06. Insertion of a drug-eluting stent is classified to 36.07. If coronary artery stent stenosis does occur, assign code 996.72 ( AHA Coding Clinic for ICD-9-CM, 2001, third quarter, page 20).

• Atherectomy is classified to codes 36.01, 36.02, or 36.05.

• Brachytherapy (92.27)

Coding and sequencing for coronary artery disease are dependent upon 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 leading supplier of coding and classification systems to nearly 4,000 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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