Dobutamine stress echocardiography in paradoxical low-flow, low-gradient aortic stenosis with mitral regurgitation

An 86-year-old man was referred to our hospital with heart failure. Transthoracic echocardiography (TTE) demonstrated paradoxical low-flow, low-gradient aortic stenosis (AS) (stroke volume index, 26.2 mL/m²; aortic valve area calculated with the standard continuity equation, 0.78 cm²; mean transvalvular gradient, 20.7 mmHg; aortic valve peak velocity, 3.0 m/s) with mildly reduced left ventricular ejection fraction (LVEF) of 52% with mild to moderate aortic regurgitation and moderate to severe mitral regurgitation (MR) due to annular dilation. Computed tomography revealed severe calcified bicuspid aortic valve with a calcium score of 2625 arbitrary units. Dobutamine stress echocardiography (DSE) was performed to confirm contractile reserve and AS severity. During the DSE, LVEF improvement leading to a reduction in left ventricular end-diastolic volume (LVEDV) and mitral tethering forces might contribute to MR improvement from severe to moderate at 20 μg/kg/min, while Vmax increased from 2.5 m/s at 10 μg/kg/min to 4.1 m/s at 20μg/kg/min. After transcatheter aortic valve replacement (TAVR), post-operative TTE showed that the improvement of LVEF and LVEDV led to dramatically decrease in MR from severe to mild despite no change in medications (panels A–E, Supplementary material online, Videos). His shortness of breath markedly improved, and he was discharged.

Given that the stroke volume is reduced in the presence of MR, the combination of AS and MR raises important challenges regarding severity grading and therapeutic management. We report that DSE might be useful in a patient with paradoxical low-flow low-gradient AS with moderate to severe MR to confirm AS severity and to predict whether concomitant functional MR would reduce after aortic valve intervention.

Panels

Severe calcification of aortic valve with right–left cusp fusion with a calcium score of 2625 arbitrary units (A); moderate to severe mitral regurgitation due to annular dilation (effective regurgitation orifice area 0.24 cm² and regurgitant volume 43 mL by proximal isovelocity surface area method) with increased LVEDV of 118 mL (normal range: 65–99 mL), mild to moderate aortic regurgitation (vena contracta width: 0.46 cm), and paradoxical low-flow, low-gradient aortic stenosis (AS) (stroke volume index to body surface area, 26.2 mL/m²; aortic valve area calculated with the standard continuity equation, 0.78 cm²; mean transvalvular gradient, 20.7 mmHg; aortic valve peak velocity [Vmax], 3.0 m/s) (B); dobutamine stress echocardiography. Pulsed wave Doppler at the left ventricular outflow tract (the upper panels), continuous wave Doppler at the aortic valve (the middle panels), and MR jet by colour Doppler echocardiography (the lower panels) during the dobutamine stress echocardiography. Aortic valve Vmax dramatically increased from 10 μg/kg/min to 20 μg/kg/min at DSE while the severity of MR decreased from severe to moderate (C); transfemoral TAVR with the 29 mm SAPIEN 3 (Edwards Lifesciences, Irvine, CA, USA) (D); post-operative transthoracic echocardiography showed improved LV size and residual mild MR after TAVR (E).

Supplementary material

Supplementary material is available at European Heart Journal – Case Reports.

Data availability

The data underlying this article are available in the article and its Supplementary data online.