Aims: Septal flash (SF), a marker of left ventricular (LV) dyssynchrony in the presence of a left bundle branch block (LBBB), has been shown to predict improved ventricular function and outcome when corrected with cardiac resynchronization therapy. We hypothesized that a SF is present in patients receiving right ventricular (RV) pacing and its presence and extent could predict the development of LV dysfunction and remodelling.
Methods and results: Seventy-four consecutive patients receiving conventional RV pacing (>6 months, >85% paced) were studied with two-dimensional (2D) echocardiography. Indications for pacing were sinus-node dysfunction and atrioventricular conduction disorders. The presence of a SF was determined on stepwise advanced 2D echocardiographic views and confirmed using greyscale M-mode. Septal flash excursion was quantified by the amplitude of the early inward motion, measured from QRS onset to maximal inward motion. Fifty-seven (of 74; 77%) patients receiving RV pacing had a detectable SF. Patients with a SF had lower LV ejection fraction (EF) (52 ± 10 vs. 60 ± 4%, P < 0.001) and greater indexed end-systolic volume (33 ± 16 vs. 23 ± 5 mL/m2, P < 0.001). Receiver operating characteristic analysis demonstrated that a SF of 3.5 mm was the optimal cut-off value (area under the curve = 0.95) to identify reduced LV function (EF < 50%) with a sensitivity of 91% and a specificity of 90%.
Conclusion: A SF was present in a majority of patients receiving conventional RV pacing and its magnitude was related to LV dysfunction and adverse remodelling. Given the similarities observed in LBBB and pacemaker-induced dyssynchrony, SF magnitude might be a predictor for the development of LV dysfunction and adverse remodelling in patients receiving conventional RV pacing.