Things We Do For No Reason: Echocardiogram in Unselected Patients with Syncope

The “Things We Do for No Reason” (TWDFNR) series reviews practices that have become common parts of hospital care but which may provide little value to our patients. Practices reviewed in the TWDFNR series do not represent “black and white” conclusions or clinical practice standards, but are meant as a starting place for research and active discussions among hospitalists and patients. We invite you to be part of that discussion. https://www.choosingwisely.org/

Syncope is a common cause of emergency department (ED) visits and hospitalizations. Echocardiogram is frequently used as a diagnostic tool in the evaluation of syncope, performed in 39%-91% of patients. The diagnostic yield of echocardiogram for detecting clinically important abnormalities in patients with a normal history, physical examination, and electrocardiogram (ECG), however, is extremely low. In contrast, echocardiograms performed on patients with syncope with a positive cardiac history, abnormal examination, and/or ECG identify an abnormality in up to 29% of cases, though these abnormalities are not always definitively the cause of symptoms. Recently updated clinical guidelines for syncope management from the American College of Cardiology now recommend echocardiogram only if initial history or examination suggests a cardiac etiology, or the ECG is abnormal. Universal echocardiography in patients with syncope exposes a significant number of patients to unnecessary testing and cost and does not represent evidence-based or high-value patient care.

CLINICAL SCENARIO

A 57-year-old woman presented to the ED after a syncopal episode. She had just eaten dinner when she slumped over and became unresponsive. Her husband estimated that she regained consciousness 30 seconds later and quickly returned to baseline mental status. She denied chest pain, shortness of breath, or palpitations. Her medical history included hypertension and hypothyroidism. Her medication regimen was unchanged.

Vital signs, including orthostatic blood pressures, were within normal ranges. A physical examination revealed regular heart sounds without murmur, rub, or gallop. ECG showed normal sinus rhythm, normal axis, and normal intervals. Chest radiograph, complete blood count, chemistry, pro-brain natriuretic peptide (pro-BNP), and troponin were within normal ranges.

BACKGROUND

Syncope, defined as “abrupt, transient, complete loss of consciousness, associated with inability to maintain postural tone, with rapid and spontaneous recovery,”¹ is a common clinical problem, accounting for 1% of ED visits in the United States.² As syncope has been shown to be associated with increased mortality,³ the primary goal of syncope evaluation is to identify modifiable underlying causes, particularly cardiac causes. Current guidelines recommend a complete history and physical, orthostatic blood pressure measurement, and ECG as the initial evaluation for syncope.¹ Echocardiogram is a frequent additional test, performed in 39%-91% of patients.^4-8

WHY YOU MAY THINK ECHOCARDIOGRAM IS HELPFUL

Echocardiogram may identify depressed ejection fraction, a risk factor for ventricular arrhythmias, along with structural causes of syncope, including aortic stenosis, pulmonary hypertension, and hypertrophic cardiomyopathy.⁹ Structural heart disease is the underlying etiology in about 3% of patients with syncope.¹⁰

Prior guidelines stated that “an echocardiogram is a helpful screening test if the history, physical examination, and ECG do not provide a diagnosis or if underlying heart disease is suspected.”¹¹ A separate guideline for the appropriate use of echocardiogram assigned a score of appropriateness on a 1-9 scale based on increasing indication.¹² Echocardiogram for syncope was scored a 7 in patients with “no other symptoms or signs of cardiovascular disease.”¹² Only 25%-40% of patients with syncope will have a cause identified after the history, physical examination, and ECG,^13,14 creating diagnostic uncertainty that often leads to further testing.

WHY ECHOCARDIOGRAM IS NOT NECESSARY IN ALL PATIENTS

Several studies have found that transthoracic echocardiogram has an extremely low diagnostic yield in patients with no cardiac history and a normal physical examination and ECG^4-8,15 (Table). A prospective study by Sarasin et al.¹⁵ identified 155 patients with unexplained syncope after an initial ED evaluation. All patients underwent echocardiogram, carotid massage, 24-hour Holter monitor, tilt-table testing, and electrophysiology testing if indicated. Patients were stratified by the presence of ECG abnormalities, defined as any arrhythmia or finding other than nonspecific ST and T wave abnormalities, or abnormal cardiac history, defined as documented coronary artery disease, valvular disease, or cardiomyopathy. None of the 67 patients with normal ECG and a negative cardiac history had findings on echocardiogram to explain syncope.