3.2 Definition of LBBAP
The definition of LBBAP was described in seven studies and omitted in
one. Confirmation of LBBAP was made by comprehensively reviewing the
following findings: 1) the only criterion used in all seven studies was
paced QRS morphology, presented with a right bundle branch block
morphology pattern in lead V1; 2) abrupt shortening of Stim-LVAT
(stimulus to peak of the R wave) in leads V5 and V6 was used in four
studies; 3) observed left bundle branch potential in pacing leads was
used in four studies; and 4) demonstration of the transition from
nonselective LBBP to selective LBBP was used in two studies. Only one
study used contrast to ensure the location of the lead in the
interventricular septum.