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).