Angina Pectoris


MS-DRG	CMS DRG (Prior to 10/1/2007)
311	Angina Pectoris	140	Angina Pectoris

The below listed angina guidelines are not inclusive. The coder should refer to the applicable Coding Clinic guidelines for additional information. The Centers for Medicare & Medicaid Services considers Coding Clinic, published by the American Hospital Association, to be the official source for coding guidelines. Hospitals should follow the Coding Clinic guidelines to assure accuracy in ICD-9-CM coding and DRG assignment.

Definition of Principal Diagnosis

The principal diagnosis is that condition established after study to be chiefly responsible for occasioning the admission of the patient to the hospital for care. Two or more diagnoses may equally meet the definition for principal diagnosis. This is in terms of the circumstances of admission, diagnostic work-up and/or therapy provided. Be aware that there is a difference between admitting a patient to treat two conditions and two conditions being present at the time of admission. The principal diagnosis is always the reason for admission.

Documentation to Support the Principal Diagnosis

When reviewing these diagnoses, determine if documentation is present to substantiate the principal diagnosis. If the principal diagnosis is angina, determine if the etiology of the angina is known and if the type of the angina is correct. If a cause is substantiated for the angina it is necessary to have a physician clarify the principal diagnosis, because when the cause of the unstable angina or angina pectoris is known, the cause should the principal diagnosis.

Coding Guidelines

Aborted myocardial infarction

A patient presented with severe chest pain, received TPA administration and subsequently showed no actual myocardial injury. The patient was transferred to another facility for further diagnostic testing. The principal diagnosis is an aborted myocardial infarction, coded 411.1, intermediate coronary syndrome. No underlying cause was identified. Code 411.81, coronary occlusion without myocardial infarction, is not used because no occlusion was identified. (See Coding Clinic, second quarter 2001, page 7.) If TPA administration does not avert or abort an acute myocardial infarction, the diagnosis is the acute MI and no code is assigned for the angina. (See Coding Clinic, second quarter 2001, pages 8 and 9.)

Accelerated angina

Accelerated angina should be coded to 411.1, intermediate coronary syndrome. (See Coding Clinic, first quarter 2003, pages 12 and 13.)

Acute coronary syndrome/acute ischemic syndrome

These are coded 411.89, other acute and subacute forms of ischemic heart disease, Other. (See Coding Clinic, third quarter 2001, page 14.)

Acute myocardial injury

Acute myocardial injury without infarction is coded 411.89. (See Coding Clinic, first quarter 1992, pages 9 and 10.)

Angina/coronary artery disease (CAD)

A patient was admitted with unstable angina, which was secondary to CAD of the native vessels. The CAD was due in part to secondhand tobacco smoke exposure. The principal diagnosis is CAD of native vessel (414.01) with secondary diagnoses of unstable angina (411.1) and secondhand tobacco smoke (E869.4). (See Coding Clinic, second quarter 1996, page 10.)

Code 414.0 had fifth digits added effective 10-1-94. (See Coding Clinic, second quarter 1995, pages 17-19.)

Coding and sequencing guidelines for angina and CAD in Coding Clinic, volume 10, number 5 1993, pages 17-24, supersedes advice published in Coding Clinic, third quarter 1990, pages 6-10.

Angina is a symptom. Therefore, when the cause is known the cause would be the principal diagnosis. If the cause of the angina is unknown, then the angina would be principal diagnosis. (See Coding Clinic, third quarter 2001, page 15; Coding Clinic, second quarter 1997, page 13; Coding Clinic, second quarter 1995, pages 18-19; Coding Clinic, second quarter 1994, page 15; Coding Clinic, volume 10, number 5 1993, pages 19 and 20; and Coding Clinic, fourth quarter 1993, pages 43 and 44.)

strong Codes 411.1/411.81

Code 411.1, intermediate coronary syndrome is not used with code 411.81, acute ischemic heart disease without myocardial infarction (MI). (See Coding Clinic, first quarter 1991, page 14.) No code from category 411 is used when an acute myocardial infarction (AMI) has occurred, except 411.0, postmyocardial infarction syndrome, and 411.1, when postinfarction unstable angina is present. (See Coding Clinic, second quarter 1995, page 19, and Coding Clinic, third quarter 1991, page 24.)

Coronary atherosclerosis of transplanted heart

Code 414.06, coronary atherosclerosis of coronary artery of transplanted heart, is a new code that was created effective October 1, 2002. (See Coding Clinic, fourth quarter 2002, pages 53 and 53.)

Postinfarction angina

A code for postinfarction angina and a code for an AMI may be used on the same patient during the same episode of care. The postinfarction angina is coded to the type of angina documented by the physician. Unstable angina is coded 411.1 and angina pectoris is coded 413.9. (See Coding Clinic, second quarter 1995, page 19, and Coding Clinic, fourth quarter 1994, page 55.)

Unstable angina/AMI

If a patient is admitted with unstable angina and it is determined after study the patient had an AMI, only the AMI is coded. The unstable angina is considered integral to the AMI. (See Coding Clinic, fourth quarter 1993, pages 39 and 40, and Coding Clinic, second quarter 1990, page 15, ODX#3.)

Unstable angina/history of MI

If a patient is admitted for unstable angina and has a history of an MI three years ago and the angina is medically treated during the admission, the unstable angina, coded 411.1, is the principal diagnosis and a history of an MI, coded 412, is the secondary diagnosis.

If the MI had occurred within eight weeks of the admission, the secondary diagnosis code would be 410.X2. (See Coding Clinic, volume 10, number 5 1993, pages 18-20 and 23.)