Summary Of Evidence

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Analysis of Evidence

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CARDIOVASCULAR STRESS TESTING

A cardiovascular stress test is a diagnostic test designed to evaluate a patient for the presence or the severity of coronary artery disease (CAD), exercise-induced arrhythmias or hemodynamic changes, and/or cardiac functional capacity.

The cardiovascular stress test is performed using continuous electrocardiographic monitoring (ECG), monitoring blood pressure and pulse, and measuring changes in cardiac electrical activity during and after the use of a cardiac stressor (exercise or a drug). Exercise-induced changes in the ST-T segment of the ECG are measured and correlated with each level of cardiac stress achieved during the test.

The patient’s heart is stressed by walking, then by running on a treadmill, or by riding a stationary bicycle, or by climbing up and down steps. When the patient is unable to perform exercise (e.g., is unable to walk, run, or bicycle), cardiac stress may be induced with intravenous (IV) medication. An interpretation and written report includes a review of the actual ECG recordings of the raw unprocessed data, for comparison with any averages the exercise test monitor generates.

STRESS ECHOCARDIOGRAPHY

Stress echocardiography adds a sound wave image of the heart (echocardiogram) to the electrical monitoring. A two-dimensional (2-D) echocardiographic image of the heart is made and recorded during rest. A second 2-D image is made 30 seconds to two minutes after exercise. The two images are compared and the changes noted.

Stress echocardiography can measure exercise-induced changes in regional ventricular wall motion, ventricular wall thickness, ventricular end-systolic volume, and ventricular ejection fraction (LVEF). Such changes offer mechanical evidence of exercise-induced cardiac muscle dysfunction, presumably due to reduced blood flow through one or more diseased coronary arteries.

RADIONUCLIDE IMAGING

Selected patients may have electrocardiographic findings that make interpretation difficult or other factors that make it reasonable and necessary to perform cardiovascular stress testing in association with radionuclide imaging. As indicated in the ACCF/ASNC/ACR/AHA/ASE/SCCT/SCMR/SNM 2009 Appropriate Use Criteria for Cardiac Radionuclide Imaging, “In general, use of cardiac radionuclide imaging (RNI) for diagnosis and risk assessment in intermediate- and high-risk patients with coronary artery disease (CAD) was viewed favorably, while testing in low-risk patients, routine repeat testing, and general screening in certain clinical scenarios were viewed less favorably. Additionally, use for perioperative testing was found to be inappropriate except for high selected groups of patients.”

INDICATIONS OF COVERAGE

Cardiovascular Stress Testing:

A cardiovascular stress test is covered for a patient who:

• Has signs or symptoms consistent with CAD:
• Angina pectoris or anginal equivalent symptoms,
• Cardiac rhythm disturbances,
• Unexplained syncope,
• Heart failure, or
• Significant atherosclerotic vascular disease elsewhere in the body (e.g., carotid obstructive disease, peripheral vascular disease involving the lower extremities, or abdominal aortic aneurysm.
• Has a metabolic disorder known to cause CAD:
• Diabetes mellitus,
• Syndrome X, or
• Atherogenic hypercholesterolemia.
• Has an abnormal ECG consistent with CAD.
• Needs an evaluation for progression of CAD with the potential for a change in treatment:
• Following coronary artery bypass graft (CABG) surgery;
• Following a myocardial infarction (MI);
• Following a percutaneous transluminal coronary angioplasty (PTCA), atherectomy, intracoronary thrombolysis, or other coronary revascularization procedure;
• Following medical treatment to reverse or stabilize CAD; or
• For a history of a coronary artery ischemic event without symptoms (e.g., a prior “silent MI”).
• Needs an evaluation as part of a preoperative assessment when intermediate- or high-risk for CAD is present and surgery is likely to induce significant cardiac stress.
• Needs an evaluation when information from the clinical assessment does not adequately assess functional capacity when such information is needed to manage the patient (e.g., for a patient with angina to assess the level of exercise tolerance for treatment planning).

Stress Echocardiogram

A stress echocardiogram is reasonable and necessary in addition to an electrical stress test in the following instances:

• An electrical stress test alone is not useful or effective, and a stress echocardiogram is needed. Such circumstances may include:
• An abnormal resting ECG due to digitalis, left ventricular hypertrophy, bundle branch block, preexcitation syndrome (Wolff-Parkinson-White), electronically paced ventricular rhythm, or greater than 1 mm of resting ST depression;
• A prior equivocal stress ECG; or
• A history of posterior wall MI.
• The patient has significant valvular heart disease, and measuring the physiologic changes with exercise is necessary to determine the need for a valve intervention,
• When needed to determine the significance or the extent of myocardial ischemia (or scar), or to assess myocardial viability (e.g., risk stratification following acute myocardial infarction),
• When information from the clinical assessment and an electrical stress test does not adequately assess functional capacity, and such information is needed to manage the patient (e.g., for a patient with angina and left bundle branch block to assess the level of exercise tolerance for treatment planning),
• When needed to aid in diagnosis of hypertrophic or dilated cardiomyopathy,
• When needed to differentiate ischemic from non-ischemic cardiomyopathy,
• As part of a preoperative evaluation of a patient who is at intermediate or high risk for CAD when the surgery is likely to induce significant cardiac stress.

Radionuclide Imaging

The medical necessity for use of RNI must be independently documented in the medical record. Documentation reference to the ACCF/ASNC/ACR/AHA/ASE/SCCT/SCMR/SNM 2009 Appropriate Use Criteria for Cardiac Radionuclide Imaging, or a similar standard will help to assure sufficient evidence that the testing is reasonable and necessary

LIMITATIONS OF COVERAGE:

Cardiovascular stress testing would not be considered “Reasonable and Necessary” when:

• The incremental information obtained from a repeat test or from the addition of an echocardiogram to an electrical stress test is of no clinical relevance.
• The results of the test have no potential to affect the treatment of the patient, such as when the patient has a severe comorbidity that is likely to limit life expectancy and/or likely to limit his/her candidacy for revascularization.
• Secondary conditions will potentially decrease both the sensitivity and specificity of testing (e.g., immediate postoperative period, anemia, or infection).
• A stress test is performed too frequently (See the Utilization Guidelines section).

Medicare will not cover cardiovascular stress testing:

• For Screening CAD (e.g., in a patient without signs or symptoms of CAD), such as for the presence of risk factors— smoking, obesity, family history of CAD, but no personal history of vascular disease or related metabolic disorder.
• When used solely to motivate changes in lifestyle.
• To qualify a patient for a noncovered service, such as fitness training, a weight loss program, or an occupational fitness evaluation.
• For a preoperative assessment prior to either a noncovered surgery or a covered surgery if the reasonable and necessary criteria for the testing is not documented.

A stress echocardiogram is not reasonable and necessary if performed simultaneously with the following additional tests:

• Radionuclide ventriculography;
• A myocardial perfusion imaging stress test with or without pharmacological stress.

Typically, a patient will not require both a stress echocardiogram and a stress nuclear test for the same clinical problem.