Dobutamine Stress Echocardiography in Low-Gradient Aortic Stenosis

Importance Guidelines recommend the use of Dobutamine stress echocardiography (DSE) in patients with low-gradient aortic stenosis (AS) and left ventricular ejection fraction (LVEF) <50%. However, a paucity exists in DSE data when LVEF>35%. Objective To examine the diagnostic accuracy of DSE, in patients with low-gradient AS with a wide range of LVEF and to examine the interaction between the diagnostic accuracy of DSE and LVEF. Design, Setting and Participants Patients with mean-gradient<40 mmHg, AVA<1.0 cm2, and stroke volume index≤35 mL/m2 undergoing DSE and Cardiac Computer Tomography (C-CT) were identified from three prospectively collected patient cohorts, and stratified according to LVEF; LVEF<35%, LVEF 35-50% & LVEF>50%. Exposure DSE and C-CT was performed on patients with low-gradient AS Main outcomes and measures Severe AS was defined as AVC score ≥2000 AU among men, and ≥1200 AU for women on C-CT. Results Of 221 patients included in the study, 78 (35%) presented with LVEF<35%, 67 (30%) with LVEF 35-50%, and 76 (34%) with LVEF>50%. Mean-gradient and Vmax during DSE showed significantly diagnostic heterogeneity between LVEF groups, being most precise when LVEF<35% (both AUC=0.90), albeit with optimal thresholds of 30 mmHg & 377 cm/s, and a limited diagnostic yield in patients with LVEF≥35% (AUC=0.67 & 0.66 in LVEF 35-50% and AUC=0.65 & 0.60 in LVEF≥50%). Using guideline thresholds led to a sensitivity/specificity of 49%/84% for all patients with LVEF<50%. Conclusion and relevance While DSE is safe and leads to an increase in stroke volume in patients with low-gradient AS regardless of LVEF, the association between DSE gradients and AS severity assessed by C-CT demonstrates important heterogeneity depending on LVEF, with highest accuracy in patients with LVEF<35%.