Optimising Pacing for Contractility 2

Overview

The investigators have demonstrated that they can reliably identify an optimum heart rate range for contractility of the left ventricle in patients with chronic heart failure (CHF). They have also demonstrated in an acute cross-over and a small parallel group feasibility study that keeping the heart rate in this range (versus standard rate-response programming) in patients with CHF is associated with increased exercise time on a treadmill (around 60s or 10%). They now want to explore in a randomised, placebo-controlled 3-arm parallel group trial whether optimal programming versus standard rate-response programming versus no rate-response programming for 6 months leads to appreciable improvements in exercise time and quality of life, while having no adverse effects on left ventricular function and battery longevity and what the mechanisms of this might be. 450 patients with CHF and a pacemaker will undergo the non-invasive echocardiographic assessment to establish the force frequency relationship and the optimal heart rate for contractility. They will then perform a treadmill walk test, complete quality of life questionnaires and be offered the opportunity to participate in a series of mechanistic substudies. They will then be randomised to optimal rate-response settings, standard rate response settings or no rate-response settings and followed up at 6 months at which point the tests will be repeated.

Detailed Description: Design: This will be a randomised, double-blind 'placebo' controlled trial of optimised programming versus standard rate-response settings, aiming to determine whether the short term improvements translate into longer term benefits. Study participants: 450 adult patients (\>18years). Study Procedures: Patients attending the heart failure clinic, the pacemaker clinic or previous research participants will be approached with a standard letter and information sheet and then a telephone call to make sure any remaining questions are answered. Patients agreeing to participate will attend the clinical research facility (CRF) and will be asked to sign a consent form. Each patient will have a standard device check, check of their demographic data, and co-morbidities. The investigators will record a resting cardiac ultrasound, and measure the force frequency relationship (FFR) to determine critical heart rate (HR), and the optimal range of HR rise. All images will be stored for offline analysis. Participants will then be asked to do a symptom-limited walk test on the treadmill (until they cannot do any more). At this first visit, participants will also complete quality of life questionnaires and be invited to participate in substudies including cardiac magnetic resonance, blood tests, tests of autonomic dysfunction. All of these activities will take place in the Clinical Research Facility at Leeds General Infirmary. Randomisation: Each patient will then be randomised to either optimised programming (n=225) as predicted by their force-frequency curve (n=200), standard settings (n=112) or no rate response programming (n=113). In the optimised group, programming will keep heart rates below the critical HR. Randomisation will be by a random number generator and programming will be undertaken by one of my colleagues to maintain blinding. Follow-up: Each patient will be called at one month to check that they are tolerating any changes and will then be invited back at 6 months for a repeat resting echocardiogram, treadmill walk test and quality of life assessment. Data: All data will be stored on a bespoke Excel spreadsheet on an LTHT server in a password-protected folder. Primary Endpoint: The effects of heart rate programming that optimises heart rate for contractility on change in treadmill-based walk distance over six months in patients with heart failure and a pacemaker. Secondary endpoints: 1) the safety of pacemaker programming optimised for heart rate in patients with heart failure and a pacemaker, 2) the effect of this programming on change of quality of life at 6 months 3) the effect of this programming on change in cardiac function at 6 months. Mechanistic endpoints: 1) The effect of heart rate programming on measures of autonomic function, 2) Changes in cardiac function during exercise, 3) The effect of optimised heart rate programming on strain, wall stress and perfusion by cardiac magnetic resonance, 4) changes in biomarkers associated with heart failure