Abstract 15165: Dobutamine Stress Echocardiography in Patients With Low Flow, Low Gradient Aortic Stenosis and Preserved Lvef

Abstract

Introduction: Guidelines recommend the use of Dobutamine stress echocardiography (DSE) in case of low flow low gradient aortic stenosis (LFLG AS) when left ventricular ejection fraction (LVEF) <50%, but few data support this threshold as most studies have tested DSE when LVEF <35%. Hypothesis: To examine the feasibility of DSE in patients with LFLG AS, and the possible interaction between LVEF and accuracy of projected aortic valve area (AVA proj ) in correctly classifying severe AS defined by Cardiac Computer Tomography (C-CT). Methods: Patients with LFLG AS (aortic mean gradient <40 mmHg & AVA <1.0 cm 2 & stroke volume index (SV i ) <35ml/m 2 ) undergoing DSE were identified from two prospective cohorts, and stratified according to LVEF (<35%, 35-50% and >50%). Severe AS was defined as AVC score ≥2000 AU in males, and ≥1200 AU in females on C-CT. Results: Of 214 patients, 65 (30%) presented with LVEF <35%, 58 (27%) with LVEF 35-50%, and 91 (43%) with LVEF >50%. 97 patients presented with severe AS (32 vs 21 vs 44, p=0.26). An inverse relationship was seen between LVEF and left ventricular diameter (60±10mm vs 54±7mm vs 47±6mm, p<0.01). Although resting SV i was different between groups (26.4±6.4mL vs 27.3±5.6 vs 29.6±5.7, p<0.01), no significant differences in SV i change was seen during DSE (7.3±5.9mL vs 5.5±6.2mL vs 6.7±6.7mL, p=0.30), and patients with LVEF <35% were more likely to demonstrate flow-reserve, defined as an increase in SVi >20%; 39 (63%) vs 21 (36%) vs 44 (49%), p=0.01. AVA proj provided similar AUCs (p=0.31) (Figure 1) and cut-off points in classifying severe AS across LVEF groups: LVEF<35%: 1.02 cm 2 /accuracy 74%, vs LVEF 35-50%: 0.82cm 2 /accuracy 72% vs LVEF >50%: 0.9cm 2 /accuracy 65%. Conclusion: DSE leads to similar increases in stroke volume index (SV i ) in patients with LVEF >50% compared with LVEF ≤50%. Furthermore, the projected aortic valve area (AVA proj ) provides good accuracy for identification of true-severe AS, regardless of LVEF stratum.