Introduction:
Despite advances in the implant technique over the last a few decades,
optimal cardiac synchronization and positive response can still not be
achieved in about 30% of the patients.1 More
recently, conduction system pacing especially left bundle area (LBA)
pacing has rapidly emerged as a potential new alternative to traditional
bi-ventricular pacing through the coronary sinus (CS) and has been used
in certain cases to improve the CRT response in patients who failed
conventional CRT (figure 1). 2-4 Nevertheless, even
with LBA pacing, there are still significant number of cases where
underlying LBBB cannot be corrected. 2-4
We here report a case where a conventional CRT non-responder underwent
an apparently “failed” LBA pacing implant as evidenced by the
inability to correct the underlying LBBB or significantly shorten the
QRS duration. However, simultaneous pacing from the previously implanted
coronary sinus lead and the apparently “failed” left bundle pacing
lead substantially narrowed the QRS and eventually led to CRT super
response.