Prognostic value of transvalvular flow rate in patients with low‐gradient severe aortic stenosis: A dobutamine stress echocardiography study

Backgrounds There are limited data on the clinical relevance of transvalvular flow rate (Q mean ) at rest (Q rest) and at peak stress (Q stress ) during dobutamine stress echocardiography (DSE) in patients with low‐gradient severe aortic stenosis (LG‐SAS). Methods We retrospectively analyzed the clinical data of patients with LG‐SAS who underwent DSE. LG‐SAS was defined as an aortic valve (AV) area index of < .6 cm 2 /m 2 and a mean AV pressure gradient (AVPG) of < 40 mm Hg. The primary endpoint included all‐cause death and heart failure hospitalization. Results Of 100 patients (mean age 79.5 ± 7.3 years; men, 45.0%; resting left ventricular ejection fraction [LVEF] 52.1% ± 15.9%; resting stroke volume index 35.8 ± 7.7 mL/m 2 ; Q rest 171.8 ± 34.9 mL/s), the primary endpoint occurred in 51 patients during a median follow‐up of 2.84 (interquartile range 1.01–5.21) years. When the study patients were divided into three subgroups based on Q rest and Q stress , the multivariate analysis showed that Qrest < 200 mL/s and Qstress ≥200 mL/s (hazard ratio 3.844; 95% confidence interval 1.143–12.930; p = .030), as well as Q rest and Qstress < 200 mL/s (hazard ratio 9.444; 95% confidence interval 2.420–36.850; p = .001), were significantly associated with unfavorable outcomes with Q rest and Qstress ≥200 mL/s as a reference after adjusting for resting LVEF, resting mean AVPG, chronic kidney disease, New York Heart Association functional class III/IV, and AV replacement. Conclusions Flow conditions based on the combination of Q rest and Q stress are helpful for risk stratification in LG‐SAS patients.