Figure legend:
A: Initial ECG upon presentation, showing high degree AV block with an escape rhythm probably arising from the left posterior fascicle. B . ECG post insertion of left bundle branch pacing lead. Notice the stimulus to QRS iso-electric segment of 30 ms, a narrow QRS of 103 ms and a left anterior fascicular block pattern suggesting left posterior fascicular capture. C .ECG post CRT-D upgrade: almost simultaneous direct left bundle branch and LV postero-lateral wall stimulation, QRS morphology is similar to panel B with minor differences (see text).