Does Cardiac Resynchronization Therapy Benefit Patients with Non-Left Bundle Branch Block Prolonged QRS Patterns?

PURPOSE OF REVIEW: We sought to assess the utility of CRT in patients with non-LBBB.

RECENT FINDINGS: CRT has an established role as a device-based therapy for patients with HF with systolic dysfunction and intraventricular conduction disease, specifically LBBB. In modern practice, the use of CRT in non-LBBB patients remains controversial, with high rates of non-response for CRT in patients with RBBB, in particular. Recent studies have identified sub-populations of non-LBBB patients that respond to resynchronization, such as those with prolonged PR intervals (≥ 230 ms), with RBBB and concomitant left-sided delay and those with significant burden of right ventricular pacing. As technology has advanced to allow for detailed mapping of LV electrical and mechanical function, benefits have been found with placement of LV leads utilizing intra-procedural mapping to target areas of greatest electrical activation delay or mechanical dyssynchrony, leading to more widespread benefit through the more specific application of CRT.