Physical and Physiologic Effects of Dobutamine Stress Echocardiography in Low-Gradient Aortic Stenosis

Background: Dobutamine stress echocardiography (DSE) is a useful tool for assessing low-gradient significant aortic stenosis (AS) and contractile reserve (CR), but its prognostic utility has become controversial in recent studies. We evaluated the impact of DSE on aortic valve physiological, structural and left ventricular parameters in low gradient AS. Methods: Consecutive patients undergoing DSE for low-gradient AS evaluation from September 2010 to July 2016 were retrospectively studied, and DSE findings divided into four groups with and without severe AS and CR. Relationships between left ventricular chamber quantification, CR, aortic valve Doppler during DSE and calcium score (by CT) were analysed. Results: There were 258 DSE studies performed on 243 patients, mean age 77.6±10.8 years and 183 (70.1%) were male. With increasing dobutamine dose, apart from systolic blood pressure, left ventricular ejection fraction, flow, cardiac power output and longitudinal strain magnitude, along with aortic valve area and mean aortic gradient all significantly increased (P<0.05). Flow and mean gradient increased in both the presence and absence of CR, whereas stroke volume and aortic valve area increased mainly in those with CR only. The aortic valve area increased in both patients with low and high calcium score, however the baseline area was lower in those with a higher calcium score. Conclusion: During DSE, aortic valve area increases with increase aortic valve gradient. Higher calcium score is associated with lower baseline aortic valve area, but the area valve area still increases with dobutamine even in presence of high calcium score.