Gabriele Vicedomini, Salvatore Rosanio, Giuseppe Oreto*, Carlo Meloni, Adriano Salvati, Stefano Bianchi, Cosimo Dicandia, Patrizio Mazzone, Monica Tocchi, Julio Spinelli**, Jiang Ding**, Luciano Sallusti, Sergio Chierchia, Carlo Pappone.
Department of Cardiology, Hospital S. Raffaele, Milan, *University of Messina, Italy, **Congestive Heart Failure Research Group, Guidant Corp., St.Paul, USA
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BACKGROUND. Acute left ventricular (LV) pacing has been
associated with hemodynamic improvement in patients with congestive heart failure (CHF) and wide
QRS complex. We hypothesized that pacing two LV sites simultaneously would produce faster activation
and better systolic function than single-site pacing.
METHODS. We selected 13 CHF patients (NYHA class III or IV) in normal sinus rhythm with left bundle
branch block (LBBB) and QRS>150 ms. An 8F dual micromanometer catheter was placed in the aorta
for measuring+dP/dt (mmHg/s), aortic pulse pressure (PP, mmHg), and end-diastolic pressure (EDP,
mmHg). Pacing leads were positioned via coronary veins at the posterior or posterolateral base (B)
and lateral free wall (FW). Patients were acutely paced VDD at the B, FW, and both sites (Dual-site)
with 5 AV delays (from 8 ms to PR###30 ms). Pacing sequences were executed in randomized order
using a custom external computer (Flexstim, Guidant CRM).
RESULTS. Dual-site pacing increased peak+dP/dt significantly more than B and FW pacing. Dual-site and
B pacing raised aortic pulse pressure significantly more than FW pacing. Dual-site pacing shortened QRS
duration by 16%, whereas B and FW pacing increased it by 1.1% and 7.6%, respectively (p=0.006).
CONCLUSION. In CHF patients with LBBB, Dual-site pacing improves systolic function more than single-site
stimulation. Improved ventricular activation synchrony, expressed by paced QRS narrowing, may explain
the additional benefit of Dual- vs. single-site pacing in enhancing contractility. This novel approach deserves
consideration for future CHF pacing studies.
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