Coronary artery disease (CAD), also known as arteriosclerotic heart disease (ASHD), is a major health care issue for millions of Americans and consumes billions of health care dollars every year. Therefore, it is important that the guidelines for coding CAD are understood for those who will be taking the certified coding specialist (CCS) and CCS-P (physician-based) examinations.
Atherosclerosis is a disease in which the arteries are hardened and narrowed due to plaque. The process of plaque buildup in the coronary arteries reduces blood flow to the heart muscle. Plaques develop when high-density lipoproteins accumulate at the site of arterial damage and platelets act to form a fibrous cap over the fat deposit, causing calcification.
CAD is a chronic disease in which there is atherosclerosis of the arteries on the surface of the heart. Documentation of chest pain is the most common symptom. Other symptoms include a feeling of choking, cold sweat, nausea, breathlessness, heartburn or fatigue. The chest pain associated with CAD is called angina. Some patients, however, do not experience any symptoms at all.
Coding Angina Pectoris
Angina pectoris is a recurring pain or discomfort in the chest that occurs when a part of the heart does not receive enough blood. Angina may occur at night or without stimulation. Types of angina associated with ASHD include:
Stable Angina: Angina that is predictable and consistent for a given individual. The discomfort can occur from over exertion, emotional stress, extreme heat or cold, heavy meals, alcohol consumption and cigarette smoking. Also know as angina pectoris.
Unstable Angina: Angina that has changed to a more frequent or more severe form. The risk of having a heart attack becomes greater.
Codes for angina commonly associated with ASHD include:
411.1 Intermediate coronary syndrome
413.9 Other and unspecified angina pectoris
Whenever a diagnosis of angina is documented in the medical record, the physician should be asked to document the specific type of angina. Unstable angina is coded with 411.1. If the type of angina is not specified, the diagnosis of angina would be assigned to code (413.9) unspecified angina.
The ICD-9-CM diagnosis codes for CAD are classified to subcategory 414.0x. Coding CAD requires documentation of the coronary artery involved and whether or not it is of a native artery, an artery of a transplanted heart, or a bypass graft. The fifth-digit subclassification identifies the coronary artery involved.
414.00 Coronary atherosclerosis of unspecified type of vessel, native or graft
414.01 Coronary atherosclerosis of native coronary artery
414.02 Coronary atherosclerosis of autologous vein bypass graft
414.03 Coronary atherosclerosis of nonautologous biological bypass graft
414.04 Coronary atherosclerosis of artery bypass graft
414.05 Coronary atherosclerosis of unspecified 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
Assign code 414.00 if the documentation does not identify the coronary artery involved. Code 414.01 is assigned if the documentation specifies that the CAD is of a native coronary artery or if there is no history of a previous coronary artery bypass graft (CABG). Code 414.02 is assigned if the documentation indicates CAD of a bypass graft using the patients own vein and code 414.03 is assigned when the graft is not of the patient's own tissue. Code 414.04 is assigned when the CAD involves an artery (mammary, brachial, etc) used as a bypass graft. Code 414.05 is assigned when the CAD is of a bypass graft but the type of bypass graft is not identified. It is incorrect to assign a code from range 414.02-414.05, merely because a patient has had previous coronary artery bypass surgery. Query the physician if the documentation in the medical record is unclear as to which artery is involved. See Coding Clinic Third Quarter 1997, pp. 15-16 and Fourth Quarter 1994, p. 49 for further discussion of this topic.
Code 414.06 is used to identify CAD of a native coronary artery of a transplanted heart and code 414.07 is assigned when the CAD is of a bypassed graft of a transplanted heart.
Patients with prior CABG who come in with acute chest pain, angina or other related symptoms may have CAD stated as their principal diagnosis. If the cause of the patient's symptoms is documented as an occlusion of a bypassed coronary artery or graft due to progression of the CAD, it is not appropriate to use code 996.03, Mechanical complication due to coronary artery bypass graft, as the principal diagnosis. In this case a code from subcategory 414.0x with the fifth digit indicating the specific type or site of the graft would be a more appropriate code assignment. For further explanation, see Coding Clinic, 2nd Quarter 1995, pp. 17-19.
The sequencing of angina and CAD has been discussed frequently in Coding Clinic. Whenever selecting principal diagnosis, keep in mind the definition of principal diagnosis, which is defined as the condition established after study to be chiefly responsible for occasioning the admission of the patient to the hospital for care.
As indicated above, patients with CAD often present due to symptoms such as unstable angina. The sequencing of the conditions is dependent on the circumstances of the admission. If the angina is secondary to CAD, the CAD is sequenced first followed by the appropriate angina code. It is not necessary that a diagnostic test be performed during that admission for the diagnosis of CAD to be established. If the physician documents CAD as the underlying cause of the angina, the CAD is listed as the principal diagnosis. It is also appropriate to assign a code for CAD as the principal diagnosis for patients admitted with angina who have a previously established diagnosis of CAD. Again, assign a code for the angina as an additional diagnosis. Once the underlying cause has been established it would be inappropriate for additional testing to be performed to re-establish the underlying cause each time a patient is admitted for the treatment of unstable angina. Review the documentation in the medical record and query the physician if the documentation is not clear.
The AHA's Coding Clinic provides further guidance for coding CAD with and without angina. Issues include:
2nd and 4th Quarter, and Number 5 1993
1st, 2nd, 3rd and 4th Quarter 1994
2nd Quarter 1995
4th Quarter 1996
3rd Quarter 1997
3rd Quarter 2001
2nd Quarter 2003
1st Quarter 2004
Review the Coding Clinic issues identified above and take the following quiz to test your knowledge of coding CAD with and without angina.
1. A patient is admitted with unstable angina. The documentation in the medical record indicates that the patient has coronary artery disease and had a CABG done years earlier. How should this case be coded?
a. 414.01, 411.1, v45.81
b. 414.00, 411.1, v45.81
c. 414.05, 411.1, v45,81
2. A patient is admitted with angina secondary to coronary artery disease. There is no mention of a past history of CABG. How should this case be coded?
a. 414.01, 413.9
b. 414.01, 411.1
c. 414.00, 411.1
3. A patient with CAD is admitted with unstable angina. The patient has had a CABG in the past and a cardiac catheterization performed during this admission indicates that there is occlusion in both the graft vessels and a native vessel. How should this case be coded?
a. 414.02, 414.01, 411.1
b. 414.01, 414.00, 411.1
c. 414.03, 414.01, 411.1
This month's column has been prepared by Cheryl D'Amato, RHIT, CCS, director of HIM, and Melinda Stegman, MBA, CCS, manager of clinical HIM services, HSS Inc. (www.hssweb.com), which specializes in the development and use of software and e-commerce solutions for managing coding, reimbursement, compliance and denial management in the health care marketplace.
Coding Clinic is published quarterly by the AHA.
CPT is a registered trademark of the AMA.
Answers to CCS PREP!: 1. b: Assign code 414.00, Coronary atherosclerosis of unspecified type of vessel, native or graft, because the record does not specify which vessel is affected. Code 414.01 would not be appropriate to show the native artery bypassed earlier, unless the record supported the current existence of CAD in a native coronary vessel. Code 414.05 would be used if the physician confirmed that CAD had developed over the previous bypass graft. As stated in Coding Clinic, Fourth Quarter 1994, p. 49, CAD of bypass graft should not be assigned based solely on the fact that the patient has atherosclerosis and has a history of bypass surgery. Assign code 411.1 as a secondary diagnosis to the unstable angina and v45.81 to identify history of CABG; 2. a: Assign code 414.01, Coronary atherosclerosis of native coronary artery as the principal diagnosis. Because there is no history of CABG, this is a native coronary vessel. However, if the documentation is unclear concerning prior bypass surgery, query the physician. This is consistent with advice previously published in Coding Clinic, Second Quarter 1995, p. 17. Code 413.9, Other and unspecified angina pectoris, is assigned as a secondary diagnosis because the type of angina is not documented; 3. a: Assign code 414.02, Coronary atherosclerosis, of autologous vein bypass graft, for atherosclerosis of the graft vessel, and code 414.01, Coronary atherosclerosis, of native coronary artery, for atherosclerosis of the native vessels. Per Coding Clinic Second Quarter 1995, p. 18, assign code 414.02 when the type of graft is unknown. In most instances, the saphenous vein is used in bypass graft surgery. Assign code 411.1, Intermediate coronary syndrome, as an additional diagnosis.