Cardiac resynchronization using fusion pacing during exercise

Abstract

Introduction: Fusion pacing requires correct timing of left ventricular pacing to right ventricular activation, although it is unclear whether this is maintained when atrioventricular (AV) conduction changes during exercise. We used cardiopulmonary exercise testing (CPET) to compare cardiac resynchronization therapy (CRT) using fusion pacing or fixed AV delays (AVD). Methods: Patients 6 months post-CRT implant with PR intervals < 250 ms performed two CPET tests, using either the SyncAV™ algorithm or fixed AVD of 120 ms in a double-blinded, randomized, crossover study. All other programming was optimized to produce the narrowest QRS duration (QRSd) possible. Results: Twenty patients (11 male, age 71 [65–77] years) were recruited. Fixed AVD and fusion programming resulted in similar narrowing of QRSd from intrinsic rhythm at rest (p =.85). Overall, there was no difference in peak oxygen consumption (V̇O2PEAK, p =.19), oxygen consumption at anaerobic threshold (VT1, p =.42), or in the time to reach either V̇O2PEAK (p =.81) or VT1 (p =.39). The BORG rating of perceived exertion was similar between groups. CPET performance was also analyzed comparing whichever programming gave the narrowest QRSd at rest (119 [96–136] vs. 134 [119–142] ms, p