What this Trial Is About

The present investigation is a non-randomised, observational study involving an unselected but highly phenotyped cohort of patients undergoing pacemaker or defibrillator implantation from whom a small sample of fat and muscle will be taken from the operation site, and, in a subgroup, from the thigh muscle. A sample of blood wil also be taken from the vein of the heart, a peripheral vein and the artery at the wrist during the procedure at different heart rates and pacing modes, to describe how heart rate and heart contraction power relate to cardiac and peripheral metabolism. The coded blood and tissue samples and anonymised clinical data will be stored in a Human Tissue Authority-approved freezer until analysis. Following the procedure, during routine visits, patients' left ventricular force frequency relationship will be assessed using cardiac ultrasound and a non-invasive cardiac monitor to further phenotype the severity and progression of their heart function over 6 months. For most patients, their involvement will end at that point although they will be monitored through electronic health records on an annual basis from that point forward for up to 5 years after the end of the study (for up to ten years after that point) to gain information on the prognostic value of the metabolic and haemodynamic testing. The present investigation will allow the investigators to advance the understanding of heart-muscle crosstalk with the goal of developing targeted interventions that could open new treatment avenues.

The Force Frequency Relationship in Heart Failure and Diabetes Mellitus: a Metabolic Aetiology?