Background: The current guidelines do not clearly state when we should upgrade a patient with right ventricular pacing (RVP) to cardiac resynchronization therapy (CRT), although the deleterious effect of chronic RVP has been established with recent trials.
Objectives: The aims of this study were to compare the long-term survival after CRT in patients upgraded from RVP with that in patients with left bundle branch block (LBBB) with QRS duration ≥ 150 ms and to compare the mechanical properties associated with CRT response in these groups.
Methods: Overall, 135 patients with implanted CRT from a single center (85 (63%) with native wide LBBB and 50 (37%) with RVP) were studied prospectively. Baseline left ventricular typical contraction pattern was determined using speckle tracking echocardiography in the apical 4-chamber view. The predefined end point was death, heart transplantation, or left ventricular assist device implantation over a period of 4 years.
Results: Patients with RVP had a significantly favorable long-term outcomes with adjusted hazard ratio of 0.36 (95% confidence interval 0.14-0.96; P = .04). Both groups had ~70% of patients with typical contraction pattern. The absence of typical contraction pattern was associated with a higher risk of an end point with adjusted hazard ratio of 5.43 (95% confidence interval 2.31-12.72; P < .001). In patients with typical contraction pattern, activation of the apical septal segment occurred more frequently in the RVP group and of the base or mid septal segments in the LBBB group.
Conclusion: Patients with HF upgraded from RVP have more favorable long-term outcomes after CRT than do native LBBB patients with QRS duration ≥ 150 ms. Contraction pattern assessment can be used to identify potential responders in the RVP group.
Keywords: Cardiac resynchronization therapy; Echocardiography; Left bundle branch block; Mechanical substrate; Right ventricular pacing.
Copyright © 2016 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.