LCD L37379: Echocardiography

The clinical use of contrast echocardiography (ECHO) is appropriate in selected patients to:

Evaluate myocardial ischemia

Quantify myocardial perfusion during stress

Identify the “area at risk” during acute myocardial infarction (AMI)

Determine the success of reperfusion interventions

Assess myocardial viability

The plethora of structural and functional information provided by transthoracic echocardiogram (TTE) is unique among diagnostic testing modalities. The rapid and noninvasive acquisition of this information has contributed to exponential application, and to potential overutilization. This policy addresses the medically necessary and appropriate application of TTE.

A. Ventricular Function and Cardiomyopathies

Changes in myocardial thickness (hypertrophy and thinning) in derived parameters of contractility, and in chamber volume and morphology, can be quantitated and charted over time by TTE. Cardiac responses to volume perturbations, chronic pressure excess and therapeutic interventions can be monitored. Recognition of the relative contributions of myocardial and valvular functional perturbations to a clinical presentation is facilitated. TTE aids in the recognition of myopathies and their classification into hypertrophic, dilated and restrictive types. Without clinically documented, discrete (abrupt change in signs and symptoms) episodes of deterioration, it is not generally medically necessary to repeat TTE assessments more frequently than annually, unless done to evaluate the response to therapeutic intervention.

Although TTE is used in the assessment of ventricular diastolic function, reproducible pathognomonic findings are not well established. In individuals with signs and/or symptoms suggestive of ventricular dysfunction, the demonstration by TTE of normal systolic function and/or ventricular hypertrophy may suggest the presence of diastolic functional abnormalities. Because the TTE findings suggesting diastolic dysfunction are less well established, when this application of TTE is the primary indication for the test, it will be expected to be performed by examiners recognized as experts in assessment and treatment of ventricular diastolic dysfunction.

Evaluation of diastolic filling parameters by Doppler ECHO is being used to help establish the prognosis in patients with congestive heart failure (CHF) and systolic dysfunction as well as to evaluate appropriate parameters of medical treatment.

B. Hypertensive Cardiovascular (CV) Disease

When there are no signs or symptoms of heart disease, the use of TTE is not covered for hypertension (HTN). HTN with clinical evidence of heart disease is a Medicare-covered indication for TTE evaluation. Left ventricular hypertrophy (LVH) correlates with prognosis in hypertensive CV disease. Certain anti-hypertensive medications have been reported to stabilize and possibly contribute to the regression of LVH. The decision to commit certain individuals with insidiously progressive borderline HTN to long-term anti-hypertensive therapy may be determined by the presence of LVH. TTE may assist in the decision to treat through the formulation and analysis of a treatment program. Baseline TTE and serial annual assessments may be medically appropriate. More frequent assessments should have explicit contemporaneous medical necessity documentation.

C. AMI and Coronary Insufficiency

TTE can detect ischemic and infarcted myocardium. Regional motion, systolic thickening perturbations and mural thinning can be quantitated and global functional adaptation assessed. The relative contributions of right ventricular ischemia and/or infarction can be evaluated. Complications of acute infarction (e.g., mural thrombi, papillary muscle dysfunction and rupture, septal defects, true or false aneurysm and myocardial rupture) can be diagnosed and their contribution to the overall clinical status placed in perspective. In the setting of acute infarction, repeat study will typically be dictated by the clinical course. If available, the use of contrast agents may improve diagnostic efficiency, and eliminate the need for additional radionuclide testing. Without clinical deterioration or unclear examination findings, repeat assessment is typically performed at discharge. The medical record must document the medical necessity of more frequent TTE assessments.

The role of TTE in the emergency room (ER) assessment of individuals presenting with chest pain is not defined at this time. This use is not accepted as a standard-of-care. For TTE to be allowed, clinical findings supporting myocardial dysfunction must be present. When these findings are not present, this use is not covered.

D. Exposure to Cardiotoxic Agents (chemotherapeutic and external)

Measures of myocardial contractility, thinning and dilatation are important in the titration of therapeutic agents with known myocardial toxicity. Baseline assessment, bimonthly during and at 6 months following therapy, is generally considered medically appropriate for exposure to many cardiotoxic agents. Following accidental exposure to known myocardial toxic agents, without abrupt change in clinical signs and/or symptoms, and when cardiac damage has been identified, annual assessment may be considered reasonable and necessary.

E. Cardiac Transplant and Rejection Monitoring

TTE is an integral part of the cardiac donor-selection and donor-recipient matching process. Evaluation focuses on analysis of ventricular function and valvular integrity. TTE is also incorporated into the management of allograft recipients. Myocardial thickness, refractile properties, contractile patterns and indices, restrictive hemodynamics, and the late development of pericardial fluid may alert the clinician to a rejection episode. None of these findings has achieved diagnostic sensitivity or specificity. Typically, TTE is performed weekly for the first 4-8 weeks following transplant, with decreasing frequency over time. Without acute rejection episodes, approximately 2 TTE examinations are typically performed yearly in chronic transplant recipients. TTE of cardiac allografts is appropriately performed serially at transplant centers by examiners with expertise in the management of cardiac allograft recipients. Uses in excess of the generally accepted frequency will be expected to have appropriate medical necessity documentation provided.

F. Native Valvular Heart Disease

Detection of mitral stenosis was among the first practical clinical applications of TTE. TTE is well established as the technique of choice for the evaluation of valvular pathology and its effect upon global myocardial function. The relative severity of multi-valve pathologies can be quantified. Visualization of the valve and valvular apparatus facilitates therapeutic decisions when competing therapeutic options exist, especially interventions for mitral stenosis. Absent acute intervention, or a discrete change in otherwise stable clinical signs and symptoms, TTE is used annually in follow-up of chronic valvular disease to document the course over time. Generally, it is not medically necessary to repeat these examinations more frequently than annually. When the patient’s plan of care includes imminent valvular surgery, more frequent exams may be necessary.

G. Prosthetic Heart Valves (Mechanical & Bio-prostheses)

TTE assessment soon after prosthetic valve implant is important in establishing a baseline structural and hemodynamic profile unique to the individual and the prosthesis. Size, position, underlying ventricular function and concomitant valve pathologies all impact this unique profile. Reassessment following convalescence (3-6 months) is appropriate. Thereafter, absent discretely defined clinical events or obvious change in physical examination findings, annual stability assessment is considered medically reasonable and appropriate. For certain indications, transesophageal echocardiography (TEE) may be the preferred modality for evaluation.

H. Acute Endocarditis

TEE has a high degree of sensitivity for endocarditis evaluation and is typically the diagnostic test of choice. TTE can provide diagnostic information; larger vegetations may be directly visualized; and valvular anatomy and ventricular function directly assessed. The complications or sequelae of acute infective endocarditis can be detected and monitored over time. Acutely, examination frequency is dictated by the individual clinical course. When the acute process has been stabilized, the frequency of serial TTE evaluation will be dictated by the residual pathophysiology and discrete clinical events, analogous to the serial assessment of chronic valvular dysfunction and/or normally functioning prosthetic valves.

I. Pericardial Disease

Detection and quantitation of the amount of pericardial effusion were among the first, and remain important, applications of TTE. Pericardial fluid accumulations as small as 20 milliliters have been reliably diagnosed by TTE. Cardiac motion and blood flow patterns demonstrated by TTE characterize the hemodynamic consequences of pericardial fluid accumulation. A collage of TTE findings has been found to be a reliable indication of cardiac tamponade. TTE can be a valuable adjunct during the removal of pericardial fluid and creation of pericardial windows by balloon techniques. Acutely, clinical status will dictate examination frequency. Absent acute pathophysiology, serial assessment of chronic stable pericardial effusion by TTE is not usually medically necessary. In a patient with evolving pericardial pathology, a limited focused TTE exam may be appropriate. TTE/Doppler findings have moderate specificity and sensitivity and can be useful in the differential diagnosis of chronic pericardial constriction.

J. Aortic Pathology

TTE can provide valuable information when acute or chronic aortic pathology is present; however, the posterior window of TEE, coupled with the more posterior position of the thoracic aorta, has rendered TEE a more determinative study. Noninvasive TTE remains the study of choice for chronic aortic pathology when images suitable for serial quantitation can be obtained. Frequency of repeat study should be guided by the pathophysiology. In some individuals, such as those with Marfan’s disease or atherosclerotic aneurysms, a focused limited follow-up exam to serially measure aortic diameters and arch diameters may be appropriate.

K. Congenital Heart Disease (CHD)

In children and small adults, TTE provides accurate anatomic definition of most CHD. Coupled with Doppler hemodynamic measurements, TTE usually provides accurate diagnosis and noninvasive serial assessment. A technically adequate TTE can obviate the need for preoperative catheterization in selected individuals. When the disease process and therapy are stable, serial assessment by TTE requires medical necessity documentation, if the frequency exceeds an annual evaluation.

L. Suspected Cardiac Thrombi and Embolic Sources

TTE is sensitive in the detection of ventricular thrombi and potentially embolic material. Limited visualization of atrial interstices and the more peripheral and superior portions of the atria render TTE less sensitive than TEE in the detection of atrial thrombus and potentially embolic material. In individuals with cardiac pathology associated with a high incidence of thromboemboli (valvular heart disease, arrhythmias - especially atrial fibrillation, cardiomyopathies and ventricular dysfunction), TTE usually provides adequate supplemental data for therapeutic decision making. It merits emphasis that a negative examination (TTE or TEE) does not exclude a cardiac embolus and the findings of thrombus or vegetation does not establish a cardiac embolic source. Repeat examinations are not generally medically required in the absence of finding potentially embolic material.

M. Cardiac Tumors and Masses

Infiltrative and ventricular tumors and masses can be visualized, their extent quantitated, and their hemodynamic consequences assessed by TTE. Right atrial space-occupying masses are usually well visualized by TTE. TEE provides a more detailed view of the left atrium and is more sensitive in quantifying mass characteristics (solid, cystic, etc.), extensions and attachments. These acute pathologies are not typically followed serially. In specific situations, such as when a tumor is not removed at surgery, and when the patient has had a cardiac myxoma removed, serial TTEs may be medically necessary to monitor for tumor size or recurrence.

N. Critically Ill and Trauma Patients

There is a role for ECHO in the management of critically ill patients and trauma victims. The diagnosis of suspect aortic or central pulmonary pathology, cardiac contusion, or a pericardial effusion may be confirmed. Perturbations of volume status may be more completely defined and management strategies modified. The frequency of these typically acute studies will be dictated by the clinical situation.

O. Arrhythmias and Palpitations

TTE is useful in defining cardiac function in which arrhythmias occur and may be useful in the management of cardiac arrhythmias. Some arrhythmias are frequently associated with underlying organic heart disease or may predispose the patient to hemodynamic deterioration. Atrial fibrillation and atrial flutter are examples of arrhythmias in which ECHO may be appropriate to assess the underlying disorder. ECHO studies are appropriate only when there is evidence of heart disease. Palpitations without clinical suspicion of arrhythmia, or evidence of heart disease, is not a covered indication for TTE.

P. Syncope

Determination of the etiology of syncopal episodes can be a difficult clinical problem. The origin may be cardiac, neurological, or due to other causes. Syncope due to cardiac origin is most commonly related to vasodepressor reflexes, bradyarrhythmias, or tachyarrhythmias. Syncope is less commonly caused by cardiac structural disorders. Patients with structurally normal hearts generally have a much more benign prognosis than those with underlying structural coronary artery disease (CAD) or cardiomyopathic disease. ECHO is only appropriate as the initial evaluation, when other findings are suggestive of valvular heart disease or obstructive cardiomyopathy.

Q. Pulmonary

Right heart failure manifesting as edema or ascites may be due to pulmonary HTN. Pulmonary heart disease may result from acute changes in the pulmonary circulation (e.g., pulmonary embolus (PE)) or chronic changes produced by chronic hypoxia that may cause significant right ventricular dysfunction and hypertrophy. ECHO may assess right ventricular size and performance and quantify the severity of pulmonary HTN using Doppler interrogation of valvular flow signals. Indications include unexplained pulmonary HTN and PE with suspected clots in the right atrium or ventricle.

R. Follow-up Studies or Limited Studies

A complete study includes a full evaluation of all aspects of the heart, including the cardiac chambers, valves, blood flow, and great vessels. The images are reviewed, measured, analyzed and interpreted by the physician. A report is prepared for the patient’s record.

S. Doppler Color Flow Velocity Mapping

Doppler color flow-velocity mapping is an appropriate addition to an ECHO when the examination is expected to contribute significant information relative to the patient’s condition or treatment plan. Typically, color flow-velocity mapping is indicated in the evaluation of the symptoms of syncope and dyspnea, some heart murmurs, valvular problems, suspected CHD, complications of myocardial infarction (MI), or cardiomyopathy. Medicare does not cover this service when performed routinely with all ECHO exams (i.e., without a clinical indication). This is true even when the results of the test reveal abnormalities. If an unsuspected finding on TTE indicates medical necessity for additional study with Doppler color flow velocity mapping, it can be covered.

T. Stress ECHO

Stress ECHO may be necessary when the evaluation could contribute significant information to the patient’s condition or treatment plan or to provide additional diagnostic information in patients with a previous non-diagnostic treadmill stress test who have signs or symptoms of suspected CAD.

Note : Stress testing (exercise tolerance testing) is not required prior to stress ECHO.

Indications and Limitations for Stress ECHO:

1. AMI

Stress ECHO is not typically performed during the acute phase of a MI when a diagnosis has been established by other methods. In selected patients, stress ECHO may be necessary when the evaluation could contribute significant information to the patient’s condition or treatment plan. Pharmacological stress is often used to provide prognostic information following MI.

2. Unstable Angina

Stress ECHO may be useful as an adjunct to other tests in the diagnosis or treatment of unstable angina only when the combination of history and other tests are not diagnostic. In selected patients, stress ECHO may be necessary when the evaluation could contribute significant information (e.g., assessment of left ventricular (LV) function) to the patient’s condition or treatment plan.

3. Chronic Ischemic Heart Disease

Stress ECHO may be useful as an adjunct to other tests in the diagnosis or treatment of chronic ischemic heart disease only when the combination of history and other tests are not contributory. In selected patients (e.g., assessment of post-coronary artery bypass grafting (CABG) symptoms for ischemia, follow-up of patients with symptomatic ischemic heart disease, or asymptomatic patients requiring follow-up that is customized to their condition and disease process) stress ECHO may be necessary when the evaluation is expected to contribute significant additional information relating to the patient’s condition or treatment plan.

Patients with conduction or repolarization abnormalities, in whom the electrocardiographic (EKG) diagnosis of stress-induced ischemia may be difficult, may require additional diagnostic information.

Patients who have a positive stress test may require stress ECHO to determine the extent and location of ischemic wall motion abnormalities.

Patients who have reduced LV ejection fraction (EF) (e.g., 4. Dilated Cardiomyopathies or Hypertrophic Cardiomyopathy

Stress ECHO may be useful in the evaluation of cardiomyopathy when the evaluation could reasonably be expected to contribute significant information to the patient’s condition or treatment plan.

Stress ECHO may also be useful to assess the gradient during exercise or to assess the response to therapy initiated to limit the gradient during exercise in patients with hypertrophic cardiomyopathy and known or suspected LV outflow tract obstruction.

5. Post-Transplant Cardiac Disease

Stress ECHO may be useful in the evaluation of ventricular dysfunction with post-transplant rejection when the evaluation could reasonably be expected to contribute significant information to the patient’s condition or treatment plan and for evaluation of known or suspected post-cardiac transplant CAD.

6. CAD

To provide additional diagnostic information in patients with moderate CAD or known or suspected CAD who are in groups known to have a high false-positive rate for EKG changes with stress tests: (Examples are women and patients who are undergoing drug therapy which may alter the EKG response).

7. Lesions

To observe the physiological significance of a lesion or to follow the changes after vascular intervention, before or after an acute invasive intervention.

To provide additional diagnostic information in patients with stenotic valvular heart disease (e.g., mitral stenosis and aortic stenosis) when results of a resting image or angiography are inadequate for diagnosing a valvular lesion causing symptomatic exercise intolerance.

8. Surgery

Stress ECHO may be useful for risk stratification prior to surgery.

Pharmacological Stress Agents

For those patients who are unable to obtain 75-100% of their age-predicted maximum heart rate through physiologic exercise, vasodilation can be achieved with the use of either dipyridamole or adenosine. Dobutamine may be used to effect myocardial stress via its inotropic effect.

1. Dipyridamole is administered intravenously at 0.56 mg/kg over a 4-minute period.

The maximum dose should not exceed 70 mg. Since the dilation effect persists, its effect typically is reversed with intravenous aminophylline, which must be available to reverse ischemia when it occurs.

Dipyridamole is relatively contraindicated in patients with:

Known bronchospastic lung disease (asthma)

Systemic hypotension (systolic blood pressure (BP) below 100 mm Hg)

AMI (less than 48 hours)

Unstable angina

2. Adenosine is administered intravenously at 140 mcg/kg/min over 6 minutes (total of 0.84 mg/kg). The vasodilation effect of adenosine is short-lived. Adenosine is contraindicated in patients with:

Second or third degree atrioventricular (AV) block

Sinus node disease except in patients with a functioning artificial pacemaker

Known or suspected bronchoconstrictive or bronchospastic lung disease

Known hypersensitivity to adenosine

3. Dobutamine is administered intravenously starting with 5 or 10 mcg/kg/min and titrated to reach the maximum heart rate for 2-5 minutes. The maximum dose administered is up to 40 mcg/kg. Max dose is not rate dependent. Atropine may be added in appropriate doses IV. Dobutamine is contraindicated in patients with:

Idiopathic hypertrophic subaortic stenosis (IHSS)

AMI

The use of a computer-based digitized imaging technique is required for stress ECHO interpretation.

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