Introduction: The Diagnostic Dilemma of Low-Gradient Aortic Stenosis
Aortic stenosis (AS) remains the most prevalent primary valve disease in developed nations. While the classic diagnosis relies on the triad of a small aortic valve area (AVA), high mean gradient (MG), and reduced leaflet motion, clinicians frequently encounter a challenging subset of patients: those with ‘discordant’ low-gradient (LG) AS. These patients present with an AVA ≤ 1.0 cm², suggesting severe stenosis, yet maintain a mean gradient < 40 mm Hg despite a preserved left ventricular ejection fraction (LVEF ≥ 50%).
The clinical management of these patients is often fraught with uncertainty. Is the low gradient a result of a truly severe stenosis in a low-flow state, or is it an overestimation of severity due to measurement errors or small body habitus? Current guidelines acknowledge that discordant LG AS may be severe, but they emphasize the need for additional confirmatory testing, such as calcium scoring or stress echocardiography. However, resting measurements often fail to capture the true burden of the disease. A recent landmark study published in Circulation: Heart Failure by Ali et al. provides much-needed clarity by utilizing the gold standard of hemodynamic assessment: invasive right heart catheterization (RHC) during exercise.
