Pacing: a new look. Don't be deceived.

CLINICAL INTRODUCTION: A 78-year-old man presents following a syncopal episode in the setting of intermittent sinus bradycardia and left bundle branch block (LBBB). With symptoms likely due to documented intermittent sinus node dysfunction, and finding of a diseased left bundle, a pacemaker was inserted (online supplementary figure 1 shows the electrode position in a PA fluroscopy view). His baseline ECG is shown in figure 1A, with a QRS width of 160 ms, and his echocardiogram revealed a left ventricular ejection fraction of 45%. His ECG day 1 postdevice insertion is shown in figure 1B. His device check confirmed excellent function. His QRS width on ECG postdevice insertion is now normalised to 80 ms.DC1SP110.1136/heartjnl-2018-313392.supp1Supplementary file 1 QUESTION: What type of device therapy has this patient received?Biventricular pacing.Right ventricular outflow septal pacing.His bundle pacing.Right ventricular apical pacing. heartjnl;104/18/1491/F1F1F1Figure 1(A) Baseline ECG and (B) day 1 postpacemaker implantation.