Abstract
Background: Cardiac resynchronization therapy (CRT) is most commonly performed with biventricular (BiV) pacing. Left ventricular (LV) only pacing is an alternative pacing configuration for CRT, but comparative studies with BiV pacing have shown inconsistent results. This may be due to differences in LV activation pattern, which could be differentially affected by atriventricular (AV) programming or atrial pacing (AP). Objective: The purpose of this study was to compare AV optimization and the effect of atrial overdrive pacing on the acute hemodynamic response of LV and BiV CRT. Methods: This study included 28 patients undergoing CRT. At implant, invasive LV dP/dt was measured by a micromanometer catheter during BiV or LV pacing in atrial sensing (AS) and AP modes at five different AV delays (AVDs), tested in randomized order. Results: Compared with intrinsic rhythm, CRT with AS increased LV dP/dt by 12% ± 10% during LV pacing and by 11% ± 11% during BiV pacing (P = .15). With atrial overdrive pacing, CRT increased LV dP/dt by 17% ± 10% with LV pacing and by 17% ± 11% during BiV pacing (P = NS vs. LV; P <.001 vs. AS). The optimal AVD was significantly longer with AP (LV 202 ± 63 ms vs. 131 ± 42 ms during AS; BiV 195 ± 71 ms vs. 134 ± 43 ms during AS) but did not differ between LV and BiV pacing. Conclusion: In this study, AP increases LV dP/dt during CRT but requires a substantially longer AVD. However, the optimal AVDs were similar for LV and BiV as were the magnitudes of the responses during CRT, suggesting that programmed AVDs are interchangeable in these two configurations.