Proportion of ORTs Relying on Aberrancy
From our 95 cases of ORT with aberrancy, only 3 showed solid evidence
proving BBB was indispensable. The others included ORTs with
pre-existing BBB, concomitant wide and narrow QRS, and those only
showing wide QRS. In the latter situation, sensed extrastimuli with
different prematurity have been attempted in straightforward cases but
failed to reactivate the blocked bundle. Therefore, it remains unknown
whether those cases were relying on aberration or not. Additionally, the
conduction velocity and refractory period of AV node and AP can be
altered by medications and autonomic nerve activity, which may influence
the dependence of aberrancy during EP study.