Whom to Image?

a.     Review of Indications

Transthoracic echocardiograms (TTE), stress echocardiograms and transesophageal echocardiograms (TEE) should only be performed if they are expected to provide clinical benefit. ASE and other societies have established appropriate use criteria (AUC) to guide imaging.5-8 Echocardiogram orders are not yet subject to decision support tools as are cardiac magnetic resonance imaging and cardiac computed tomography, but the SARS-CoV-2 outbreak highlights the need to avoid performing rarely appropriate exams.  Application of the AUC represents the first decision point as to whether an echocardiographic test should be performed.  Secondly, there are cases in which the indication for echocardiography is appropriate or may be appropriate, but the exam is unlikely to yield clinically important information in the short term with the added risk of potential disease transmission. There are two ways to identify these studies.

  • Determine which studies are “elective” and reschedule them, performing all others.
  • Identify “non-elective” (urgent/emergent) indications and to defer all others.

In cases considered for deferral, there is no significant risk to patients in terms of morbidity or mortality and no expected benefit in terms of avoiding the use of medical resources (such as emergency department visits or hospitalizations). These tests should be postponed.

Next, it is important to determine the clinical benefit of echocardiography for symptomatic patients whose SARS-CoV-2 status is unknown.  Knowing the status of a patient allows for the appropriate application of personal protective equipment (PPE) and its conservation when not needed, in addition to reducing the exposure risk to echocardiography personnel.

TEEs carry a heightened risk of spread of the SARS-CoV-2 since they may provoke aerosolization of a large amount of virus due to coughing or gagging that may result during the examination. TEEs therefore deserve special consideration in determining when and whether they should be performed, and under what precautions (described below). A cautious consideration of the benefit of a TEE examination should be weighed against the risk of exposure of healthcare personnel to aerosolization in a patient with suspected or confirmed COVID-19 and the use of PPE. TEEs should be postponed or canceled if an alternative imaging modality (e.g. off axis TTE views, ultrasound enhancing agent with TTE) can provide the necessary information.  The use of contrast enhanced computed tomography (CT) and magnetic resonance imaging (MRI) has emerged as an alternative to TEE for exclusion of left atrial appendage thrombus prior to cardioversion.9  The use of these tests to avoid an aerosolizing procedure should be balanced against the risk of transporting a patient through the hospital to the CT or MRI scanner, the need to disinfect the CT or MRI room, and iodinated contrast and radiation for CT, long scan times for MRI.  Some institutions have a dedicated CT scanner reserved for patients with COVID-19.

Similarly, treadmill or bicycle stress echo tests on patients with COVID-19 may lead to exposure due to deep breathing and/or coughing during exercise.  These tests should generally be deferred or converted to a pharmacological stress echo.

Depending on the trajectory of the outbreak, some institutions may face a crisis state with reduced availability of trained staff and/or equipment. In this setting, triage by indication may be necessary, deciding which appropriate and urgent/emergent echocardiograms will be performed and which will not, or deciding which will be performed first. This prioritization of indications will need to be done on a case-by-case basis, while accounting for many patient-level factors such as current indication, current clinical status, past medical history and the results of other tests. Involving referring physicians in the triage process is therefore essential.