Does second harmonic imaging improve left ventricular endocardial border identification at higher heart rates during dobutamine stress echocardiography?

Background: The increased heart rate during dobutamine stress echocardiogra phy (DSE) may impair endocardial border visualization. Second harmonic imag ing (SHI) enhances left ventricular (LV) border visualization compared with conventional fundamental Imaging (FI) at rest. However, its role during DS E is not well established yet. Objective: Our objective was to compare the additional value of SHI to Ii f or the LV endocardial border visualization during various stages of DSE. Methods: Eighty patients underwent DSE. Imaging was performed with both FI and SHI at rest and at low- and peak-dose dobutamine infusion. Endocardial border visualization was assessed by using a 16-segment/3-point score (0 = well visualized; 1 = poorly visualized; 2 = not visualized). Results: Heart rate increased from rest (70 +/- 13 bpm) to low-dose dobutam ine (77 +/- 17, P < .01) and showed further increase at peak dose (129 <plu s/minus> 16, P < .001 versus low dose). There was a higher prevalence of se gments with an invisible LV endocardial border with FI compared with SHI at rest (9.4% versus 6.2%, P < .0001), at low dose (10.8% versus 6.3%, P < .0 001), and at peak dose (15.0% versus 8.2%, P < .0001). There was an increas e in the number of segments with an invisible border from rest to peak stre ss by FI (P = .0001), whereas the difference was less significant for SHI ( P = .07). Conclusion: Second harmonic imaging improves visualization of the LV endoca rdial border compared with FI during DSE. The advantage of SHI over FI is m ore marked at higher heart rates than at rest.