Despite the randomized trial showing a difference in outcomes, more data are needed before changing practice, says one expert ...

A left bundle branch block occurs when electrical conduction ... Approximately 50% of left bundle branch blocks are associated with structural heart disease, while the other half are idiopathic ...

A rate-dependent LBBB can occur at times of fast heart rates. This may be caused by myocardial ischemia or refractoriness of the left bundle at faster heart rates. When occurring at heart rates ...