Cardiac Neuromodulation Therapy (CNT) "Washout" Sub-Study

Overview

This washout protocol is structured as a sub-study for patients willing to participate after finishing the double blind randomised phase of the clinical trial, NCT02837445. Devices will be turned off for a week approximately. Patients will have their PHC programmed to automatically turn off 24 hr after a medical and technical visit and remain in regular pacing. Ambulatory recording of the BP will start at the end of the visit, and continue for 24 hr after the turn off time (48 hr recording). Conversely, patients will return at the end of the first week, when a second 48 hr recording will be initiated, this time, the PHC will be programmed to turn on 24 hr later. The recordings therefore will provide data of the ON to OFF transition for the evaluation of the residual effect of PHC after 24 h and after week.

As detailed in protocol CS-03, the BackBeat Moderato system applies standard pacing signals according to a specially timed, alternating sequence short and longer atrioventricular (AV) delays, to reduce blood pressure as a treatment for hypertension. The algorithm that governs the delivery of these pacing signals is referred to as Cardiac Neuromodulation Therapy (CNT) and the signals are referred to as Programable Hypertension Control (PHC) signals, (refer to Clinical Evaluation of Safety and Effectiveness of the BackBeat Medical Moderato System in Patients With Hypertension: A Double-Blind Randomized Trial, NCT02837445) As currently used, CNT requires continuous right ventricle (RV) pacing. However, due to potentially long-term effects of CNT on baroceptor function, intermittent deactivation of CNT could reduce the overall amount of pacing without loss of efficacy. Support for this hypothesis comes from a preclinical testing of CNT that was detailed in "Chapter II - Pre-Clinical Testing" of the approved Investigator Brochure. BackBeat Medical conducted a chronic feasibility study in 4 dogs with hypertension induced by renal artery banding which were implanted with a Moderato IPG for 4 months. Results from this study showed that when CNT was turned off after 30 days of continuous CNT, there was a very slow increase in systolic pressure, approaching pre-therapy levels only several weeks later. A 50% residual effect remained at 20 days, with a total washout period of approximately 30 days. One possible explanation for this observation is that the signal beneficially changes the pressure"set point" of the baroceptor reflexes. Changes in the set point could result from changes at the level of either the pressure sensor in the carotid sinus or within the pressure regulatory region of the central nervous system; namely the nucleus tractus solitarius (NTS) in the medulla oblongata. This sub-study aims to evaluate whether and for how long the blood-pressure lowering effect of CNT persists following its cessation in patients who have been treated with CNT for a prolonged period of time.