Improved response to cardiac resynchronization therapy through optimization of atrioventricular and interventricular delays using acoustic cardiography: a pilot study.

BACKGROUND: The purpose of this pilot study was to determine the utility of acoustic cardiography for the optimization of atrioventricular (AV) and interventricular (VV) delays in cardiac resynchronization therapy (CRT). METHODS AND
RESULTS: We evaluated 14 patients (86% male, mean age 64 +/- 9 years, mean time since implant 15 +/- 18 months). Subjects were enrolled >10 weeks after CRT implant. Spiroergometry and 2-dimensional/3-dimensional echocardiography were used to assess cardiac performance for "out-of-the-box" settings (baseline settings: AV 120 ms, VV 0 ms) versus optimal settings (determined by acoustic cardiography). Cardiac performance measurements were performed 6 weeks after settings were modified. Optimal AV/VV settings were determined based on the lowest electromechanical activation time (EMAT, the time from the onset of QRS to the mitral valve component of the first heart sound). Statistical analysis was performed using a paired 2-tailed Student's t-test. In comparison to "out-of-the-box" settings, AV/VV delay optimization with acoustic cardiography improved cardiac performance as indicated by significant changes in work capacity, maximum oxygen uptake, oxygen pulse, ejection fraction, end-systolic volume, and velocity-time integral in left ventricular outflow tract.
CONCLUSIONS: AV and VV optimization by acoustic cardiography produces significant improvements in objective clinical and hemodynamic parameters in comparison to typical "out-of-the-box" settings.