Left Ventricular Lead Placement Guided by Reduction in QRS Area

Background: Reduction in QRS area after cardiac resynchronization therapy (CRT) is associated with improved long-term clinical outcome. The aim of this study was to investigate whether the reduction in QRS area is associated with hemodynamic improvement by pacing different LV sites and can be used to guide LV lead placement. Methods: Patients with a class Ia/IIa CRT indication were prospectively included from three hospitals. Acute hemodynamic response was assessed as the relative change in maximum rate of rise of left ventricular (LV) pressure (% increment LVdP/dt(max)). Change in QRS area ( increment QRS area), in QRS duration ( increment QRS duration), and % increment LVdP/dt(max) were studied in relation to different LV pacing locations within a patient. Results: Data from 52 patients paced at 188 different LV pacing sites were investigated. Lateral LV pacing resulted in a larger % increment LVdP/dt(max) than anterior or posterior pacing (p = 0.0007). A similar trend was found for increment QRS area (p = 0.001) but not for increment QRS duration (p = 0.23). Pacing from the proximal electrode pair resulted in a larger % increment LVdP/dt(max) (p = 0.004), and increment QRS area (p = 0.003) but not increment QRS duration (p = 0.77). Within patients, correlation between increment QRS area and % increment LVdP/dt(max) was 0.76 (median, IQR 0.35; 0,89). Conclusion: Within patients, increment QRS area is associated with % increment LVdP/dt(max) at different LV pacing locations. Therefore, QRS area, which is an easily, noninvasively obtainable and objective parameter, may be useful to guide LV lead placement in CRT.