Is a stress echocardiogram (echo) indicated in patients with low-flow, low-gradient aortic stenosis (LFLG AS) and preserved left ventricular ejection fraction (LV EF)?

From the Guidelines

Yes, a stress echocardiogram is indicated in patients with low-flow, low-gradient aortic stenosis (LFLG AS) and preserved left ventricular ejection fraction (LV EF), as it helps differentiate between true severe aortic stenosis and pseudosevere AS, which is crucial for appropriate management decisions. This diagnostic test is particularly useful in patients with LFLG AS and preserved LV EF, as it can help identify those with true severe AS who may benefit from valve replacement. According to the most recent guidelines, including the 2023 ESC/EACTS guidelines 1 and the 2023 ACC/AHA guidelines comparison 1, dobutamine stress echocardiography is recommended for patients with low-gradient AS, including those with preserved LV EF.

The test involves administering dobutamine in incremental doses, typically starting at 5 μg/kg/min and increasing to a maximum of 20 μg/kg/min, with echocardiographic measurements taken at each stage. In true severe AS, the valve area remains small (<1.0 cm²) despite increased flow, while the mean gradient increases significantly (>40 mmHg). In pseudosevere AS, the valve area increases (>1.0 cm²) with increased flow, while the gradient remains low. Additionally, the test provides information about flow reserve, which has prognostic implications. Patients with contractile reserve (>20% increase in stroke volume) generally have better outcomes with valve replacement than those without.

Some key points to consider when performing a stress echocardiogram in patients with LFLG AS and preserved LV EF include:

• The test should be performed in a controlled setting with careful monitoring for complications such as arrhythmias, hypotension, or symptoms of ischemia.
• The test should be terminated if the patient develops significant symptoms or hemodynamic instability.
• The results of the test should be interpreted in conjunction with other clinical and imaging data, including echocardiographic measurements of valve area and mean gradient, as well as clinical variables such as symptoms and LV function.
• The use of dobutamine stress echocardiography is supported by multiple guidelines, including the 2023 ESC/EACTS guidelines 1 and the 2023 ACC/AHA guidelines comparison 1.

Overall, a stress echocardiogram is a valuable diagnostic tool for patients with LFLG AS and preserved LV EF, and can help guide management decisions and improve outcomes for these patients.

From the Research

Indications for Stress Echocardiogram in LFLG AS with Preserved LV EF

• A stress echocardiogram may be indicated in patients with low-flow, low-gradient aortic stenosis (LFLG AS) and preserved left ventricular ejection fraction (LV EF) to assess stenosis severity and predict outcome 2.
• In patients with paradoxical LFLG AS, which is characterized by preserved LV EF, stress echocardiography can help determine the actual severity of the stenosis and predict risk of adverse events 2.
• Low-dose dobutamine stress echocardiography (DSE) is commonly used to identify truly severe stenosis in patients with classical LFLG AS, but its role in patients with preserved LV EF is less clear 3, 4.
• Aortic valve calcium scoring with multidetector computed tomography may be a preferred modality for evaluating patients with paradoxical LFLG AS or normal-flow, low-gradient AS 3, 4.

Diagnostic Challenges in LFLG AS with Preserved LV EF

• The management of LFLG AS with preserved LV EF is particularly challenging due to the uncertainty about the actual stenosis severity and the indication for aortic valve replacement (AVR) 4, 5.
• Patients with LFLG AS and preserved LV EF may have a heterogeneous disease entity, and it is crucial to rule out any diagnostic errors and pseudo-severe stenosis 5.
• Further studies are necessary to understand this disease entity and to evaluate the optimal diagnostic and therapeutic approach for these patients 5.

Therapeutic Options for LFLG AS with Preserved LV EF

• Aortic valve replacement (AVR) is a therapeutic option for patients with severe AS, including those with LFLG AS and preserved LV EF 3, 4, 6.
• Transcatheter AVR may be a suitable option for patients with LFLG AS, including those with preserved LV EF, and may be associated with similar clinical outcomes as surgical AVR 6.