Abstract 2071: Can Increased Myocardial Contractility During Dobutamine Infusion Be Reliably Measured By Speckle Tracking?
Introduction: Speckle tracking is emerging as a useful adjunct in the evaluation of myocardial function, both at rest and during stress. We assessed the hypothesis that a novel software package incorporating such technology could document the inotropic effect of dobutamine, during different stages of a stress echo.
Methods: We included 25 patients with a low pre-test probability of coronary artery disease, who were referred for dobutamine stress echo (DSE) and who had normal tests. Standard stress protocol images were taken at baseline (0μgm/kg/min), low dose (10μg/kg/min), intermediate (30μg/kg/min) and peak (40μg/kg/min). The standard images were reported by an experienced operator and the speckle analysis was done by a blinded independant observer. Mean radial strain and standard deviation (SD) were calculated for each coronary territory at each stage.
Results: At baseline mean strain in the left anterior descending was 25.4%(SD 9.1). This increased to 31.7%(10) at low dose, 57%(20) at intermediate and 73.5%(22.8) at peak. The circumflex results were 24.4%(12.5), 27.5%(7), 50.3%(14) and 61.4% (13.1) respectively and for the right coronary they were 7.5%(5.1), 18.1%(7.2), 16.1%(9.7) and 44.7%(30). When the differences in global strain were compared the incremental increase was statistically significant between low to intermediate and intermediate to peak. (p=0.009 and 0.02 respectively).
Conclusion: This is the first study in humans to show that speckle tracking is able to reliably demonstrate an incremental increase in 2D strain with increasing doses of dobutamine, in normal LV segments. As such, it has the potential to be an objective aid to the interpretation of DSE.