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CARDIAC RESYNCHRONIZATION THERAPY BY MULTIPOINT PACING IMPROVES THE ACUTE RESPONSE OF LEFT VENTRICULAR MECHANICS AND FLUID DYNAMICS: A THREE-DIMENSIONAL AND PARTICLE IMAGE VELOCIMETRY ECHOCARDIOGRAPHIC STUDY

M. Siciliano, D. Muraru, F. Migliore, A. Zorzi, S. Cavedon, F. Folino, G. Pedrizzetti, E. Bertaglia, D. Corrado, S. Iliceto, L. Badano

1. Department of Cardiac, Thoracic and Vascular Sciences, University of Padova, Italy; 2. Department of Engineering and Architecture, University of Trieste, Italy

Abstract

Introduction: Multipoint pacing (MPP) is supposed to provide a more effective CRT than conventional biventricular pacing (BiV-CONV).We compared the acute effects of MPP versus BiV-CONV and CRT-OFF) on LV function in CRT responders.
Methods: In 9 consecutive CRT patients (65±11) receiving a quadripolar LV lead (Quartet™, St. Jude Medical) and positive clinical response at 6 months, 3D echocardiography (3DE) and Echo-PIV were performed for MPP, BiV-CONV and CRT-OFF during the same session. LV acquisitions were randomly analysed in a blinded fashion.
Results: MPP resulted in shorter QRS duration and significant reduction in end diastolic volume, end systolic volume compared with CRT-OFF and BIV-CONV (p < 0.05); moreover, MPP resulted in better 3D LV ejection fraction, strain (longitudinal and circumferential), more synchronous LV contraction than CRT-OFF (p < 0.05).Flow force angle by Echo-PIV was significantly lower for BiV-CONV vs CRT-OFF (p=0.002), and for MPP vs BiV-CONV (p=0.002).
Conclusions: 3DE and Echo-PIV enabled to identify improvement in LV systolic function and fluid dynamics during MPP.This pilot study suggests that Echo-PIV could be a more sensitive echocardiographic index for evaluating the subtle effects of various CRT modalities.

Figure 1. Example of flow force angle analysis by Echo-PIV and dyssynchrony by 3D strain imaging. In MPP, the predominant direction of flow forces is more longitudinally oriented (i.e. lower force angle) than in BiV-CONV or CRT-OFF. In CRT-OFF mode, the disturbed (transversal) flow force development is associated with a more dyssynchronous myocardial deformation, as depicted by 3D longitudinal strain (LS) curves. SDI, systolic dyssynchrony index of regional longitudinal strain.