From the Guidelines
For patients with suspected coronary artery disease, a stress echocardiogram is the preferred test over a transthoracic echocardiogram (TTE) because it provides functional information on ischemia that is not available from a resting study. A standard TTE is performed while the patient is at rest and provides images of the heart's structure and function, including chamber size, wall thickness, valve function, and ejection fraction, making it useful for diagnosing various cardiac conditions like heart failure, valve disease, and congenital abnormalities 1. In contrast, a stress echocardiogram combines the imaging of a standard echo with either exercise or medication to stress the heart, allowing for the detection of coronary artery disease by identifying areas of the heart muscle that don't contract properly when under stress, suggesting inadequate blood supply 1.
Key Differences Between TTE and Stress Echo
- A TTE is used for structural heart evaluation, while a stress echo is used when coronary artery disease is suspected or needs assessment.
- Stress echos provide functional information that isn't available from a resting study, making them more specific for detecting ischemia.
- The sensitivity and specificity of stress TTE for detecting ischemic heart disease are 72% to 83% and 84% to 95%, respectively, although this has been validated primarily in symptomatic elevated risk populations 1.
Clinical Application
The choice between these tests depends on the clinical question. For patients with acute chest pain, a TTE can be used to visualize and aid in the differential diagnosis among the numerous causes of acute chest pain, and stress echocardiography can be used after ACS has been ruled out to define ischemia severity and for risk stratification purposes 1. Ultimately, the decision to use a TTE or a stress echo should be based on the individual patient's clinical presentation and the suspected underlying cardiac condition.
From the Research
Comparison of TTE Echo and Stress Echo
- TTE (Transthoracic Echocardiography) echo is a standard echocardiography test used to evaluate the heart's structure and function at rest.
- Stress echo, on the other hand, is a test that uses various stimuli to elicit myocardial contractility or provoke cardiac ischemia with simultaneous echocardiographic image acquisition of left ventricular function and valvular flow, if needed 2.
Indications for Stress Echo
- Stress echo is indicated in patients with intermediate probability of coronary artery disease, inability to perform physical exercise, and non-diagnostic resting or exercise electrocardiography 2.
- It is also used in symptomatic patients after revascularization or patients qualified for revascularization for functional assessment of coronary artery stenosis 2.
- In valvular heart disease, stress echo is recommended when there is a mismatch between resting transthoracic echocardiography findings and symptoms during activities of daily living 3.
Types of Stress Echo
- Exercise stress echo is the preferred stress modality, but pharmacological augmentation with dobutamine can be used if needed 2, 4.
- Low-dose dobutamine stress echocardiography is specifically valuable in patients with low-flow, low-gradient aortic stenosis when attempting to differentiate true severe aortic stenosis from pseudo-severe aortic stenosis 4.