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 echocardiography (DSE) may impair endocardial border visualization, second harmonic imaging (SHI) enhances left ventricular (LV) border. visualization compared with conventional fundamental imaging (FI) at rest. However, its role during DSE is not well established yet. Objective: Our objective was to compare the additional value of SHI to FI for 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 lowand 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 dobutamine (77 ± 17, P <.01) and showed further increase at peak dose (129 ± 16, P <.001 versus low dose). There was a higher prevalence of segments 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 <.0001), and at peak dose (15.0% versus 8.2%, P <.0001). There was an increase in the number of segments with an invisible border from rest to peak stress by FI (P = .0001), whereas the difference was less significant for SHI (P = .07). Conclusion: Second harmonic imaging improves visualization of the LV endocardial border compared with FI during DSE. The advantage of SHI over FI is more marked at higher heart rates than at rest.