American College of Cardiology

Quinones ET AL., ACC/AHA CLINICAL COMPETENCE STATEMENT ON ECHOCARDIOGRAPHY
J Am Coll Cardiol 2003;41:687-708

ACC/AHA Clinical Competence Statement on Echocardiography

A Report of the American College of Cardiology/American Heart
Association/American College of Physicians–American Society of Internal Medicine Task Force on Clinical Competence

Developed in Collaboration with the American Society of Echocardiography, the Society of Cardiovascular Anesthesiologists, and the Society of Pediatric Echocardiography

VI. Stress Echocardiography

Overview and Indications for the Procedure. Exercise electrocardiography is the standard noninvasive technique for the diagnosis of coronary artery disease. However, several situations (such as baseline ECG abnormalities and inability to exercise), reduce the sensitivity or specificity of exercise testing, or preclude its use entirely. In these situations, stress echocardiography is an important alternative.

There are two main modalities for performing stress echocardiography: 1) exercise stress echocardiography performed either during upright or supine bicycle exercise or immediately following treadmill exercise, and 2) pharmacologic stress echocardiography, most commonly performed using an intravenous infusion of dobutamine at a dose ranging from 5 mcg per kg per min to a maximum of 40 to 50 mcg per kg per min. Atropine is added at peak infusion dose if needed to achieve at least 85% of target heart rate. Side effects of dobutamine stress echocardiography include nausea, vomiting, headache, tremor, and anxiety. Serious complications such as myocardial infarction and death are very rare. Adenosine and dipyridamole can also be used as pharmacologic stressors. Atrial pacing using an esophageal lead or an implanted pacemaker is a third modality for performing stress echocardiography. Although it is not commonly used, this modality can provide an effective and safe method for inducing ischemia.

The normal cardiac response to stress is an increase in heart rate and myocardial contractility. Inducible myocardial ischemia is detected as failure to increase myocardial contractility or development of a new segmental wall motion abnormality. Indications for stress echocardiography include diagnosis of ischemic heart disease, evaluation of patients with known ischemic disease, and assessment of valvular heart disease.

Stress echocardiography can also be performed with spectral and color Doppler for the hemodynamic evaluation of patients with valvular heart disease. Ultrasonic contrast agents have been used to improve endocardial border detection. In the future, these agents might be used to evaluate myocardial perfusion.

Transesophageal dobutamine stress echocardiography has been used to improve endocardial visualization, but because of its invasive nature and the general improvement in transthoracic imaging with the use of contrast agents, this modality has not gained wide acceptance in clinical practice.

Minimum Knowledge Requirements for Performance and Interpretation (Table 14). Competence in performing and/or interpreting stress echocardiograms in adult patients requires all of the basic knowledge of ultrasound physics, instrumentation, and cardiac anatomy, physiology and pathology described in the section on General Principles. In addition, the requirements for stress echocardiography contain two distinct components: 1) stress testing supervision; and 2) performance and interpretation of the echocardiographic images for wall motion analysis. Stress testing supervision requires the ability to safely monitor stress in an individual with potentially severe cardiovascular disease. A recent ACC/AHA Clinical Competence Statement on Stress Testing document by Rodgers et al. ⁽¹²⁾ addressed the cognitive skills, training requirements for establishing competence and requirements for maintaining competence in stress echocardiography. The document separates the skills needed to perform and supervise the stress portion of the test from those needed to perform and interpret the echocardiographic images. Recognition and treatment of life threatening arrhythmias is particularly relevant with dobutamine stress echocardiography. This writing group has decided to adopt the recommendations made by Rodgers et al. ⁽¹²⁾ which are summarized in this section.

Assessment of segmental wall motion remains one of the most challenging aspects of echocardiographic interpretation. Thus, intensive training in echocardiography with a minimum of Level 2 training or equivalent is a prerequisite for acquiring the skills necessary to perform and interpret stress echocardiography studies ⁽¹³⁾.

Training Requirements (Table 15). Specific recommendations for training in stress echocardiography have been published recently ^(12-14) and consist of achieving Level 2 training in echocardiography plus a minimum of 100 stress studies performed under the supervision of an echocardiographer with Level 3 training and expertise in stress echocardiography, including the independent interpretation of more than 200 stress echocardiograms, and maintenance of skills as outlined Table 16 ⁽¹²⁾.

Proof of Competence (Table 16). A letter from the program training director or training supervisor is expected to document the required training activity and competence. Physicians who intend to perform stress echocardiography and who completed training before the establishment of training levels are expected to achieve training equivalent to that acquired during formal fellowship. This should be achieved in a laboratory with sufficient volume to expose the physician to the same minimum of 100 stress echocardiograms, as previously outlined, under the direct supervision of an echocardiographer with Level 3 training and expertise in stress echocardiography.

Certification by the NBE is highly desirable. Certification requires successful completion of the Adult Special Competence Examination in Echocardiography as well as documentation of training and maintenance of skills. For individuals completing training after 1998, a letter from the training director or section head documenting Level 2 training and performance/interpretation of 100 or more stress echocardiograms is required. For physicians completing cardiovascular training before 1998, a letter documenting performance and interpretation of 400 or more transthoracic echocardiograms and 100 or more stress echocardiograms during each of the two preceding years is required. This letter should be obtained from the laboratory medical director or the hospital chief of staff.

Maintenance of Competence (Table 16). The accurate assessment of regional wall motion during stress is difficult enough to require continuous exposure to an adequate mix of normal and abnormal cases in order to maintain competence. The ASE document recommended a volume of 15 stress echoes per month to remain competent ⁽¹⁴⁾. However, it was the consensus of the experts writing the ACC/AHA Competence Statement on Stress Testing that an individual with established skills could maintain competence with a volume of 100 studies per year ⁽¹²⁾. We endorse this recommendation. Physicians with a lesser volume should perform and/or interpret stress echoes in association with an experienced echocardiographer who achieves the recommended volume of studies in his or her practice. Continuing medical education in stress echocardiography is essential to keep pace with ongoing technical advances, refinements in established techniques, and applications of new methods. Minimal CME requirements are outlined in Section A. A program for continuous quality improvement in stress echocardiography should be employed, as outlined in the ASE Continuous Quality Improvement document ⁽⁶⁾.