Clinical Trial of the SonRtip Lead and Automatic AV-VV Optimization Algorithm in the PARADYM RF SonR CRT-D

Since the introduction of cardiac resynchronization therapy (CRT) on a large scale, it has been observed that approximately 30% of recipient patients are non-responsive to therapy. This non-responsiveness can be decreased by optimizing the device programming, particularly the stimulation rate, paced and sensed atrioventricular (AV) delay, and the interventricular (VV) delay. All CRT patients need a 100% rate of ventricular capture, but beyond this the achievement of therapy effectiveness requires the identification of the optimal pacing configuration, which varies among patients. The optimization of CRT systems, usually based on ultrasound imaging is time-consuming and the number of patients in need of multiple optimization procedures due to ventricular remodeling is growing rapidly. The mechanical effects of a more coordinated contraction result in a shortening of the isovolumetric contraction phase and the pre-ejection time, and an increase in LV dP/dt (change in left ventricular pressure over time. The concept of measuring contractility with an implantable accelerometer was first clinically validated through a multicenter study on a rate responsive pacing system (BEST - Living from SORIN Biomedica) in 1996. This study positively demonstrates that measurement of Peak Endocardial Acceleration signal (called PEA or SonR) is feasible and reliable in the long-term, both for the purpose of rate response and as a hemodynamic monitor of cardiac function. More recent clinical studies have demonstrated that optimal VV and AV Delays determined using algorithms based on SonR signal analysis (SonR method) are correlated with the highest hemodynamic improvement and lead to significant clinical benefit for the patients, thus reducing the rate of non-responsiveness to CRT therapy. Therefore, automatic AV and VV delay optimization in patients with CRT devices could benefit both the patient and physician.