A watch-sized implant that delivers electrical pulses to the heart could provide a breakthrough for thousands of patients living with heart failure by altering the organ’s metabolic fuel source. While healthy hearts primarily burn fat to produce the strong, efficient beats needed to circulate oxygen-rich blood, failing hearts often switch to burning glucose. This shift occurs because glucose requires less oxygen to process, but it results in a much weaker heartbeat, eventually causing the heart to overwork itself and tire out.
Research led by the University of Oxford and funded by the British Heart Foundation has demonstrated that fitting patients with a cardiac resynchronisation therapy (CRT) pacemaker can almost instantly trigger the heart to switch back to burning fat. This metabolic transition appears to be a key factor in the device’s success. Findings published in the European Heart Journal reveal that after six months of treatment, the size of the overworked left ventricle in some patients was reduced by half, significantly improving the heart’s structural health.
The study observed that pumping function—the heart’s ability to move blood throughout the body—improved by more than a third in participants following the procedure. Professor Neil Herring, a specialist in cardiovascular medicine, described the extent of the improvement as “remarkable,” particularly as the patients in the trial were already on standard heart failure medications without seeing such significant benefits. Remarkably, MRI scans confirmed that the switch from glucose to fat occurred within just two minutes of the pacemaker being activated.
Heart failure affects over a million people in the United Kingdom, with symptoms such as extreme fatigue, breathlessness, and fluid retention often severely impacting quality of life. While existing CRT pacemakers are already used to help the heart’s chambers contract in unison, this new research suggests that their ability to reset the heart’s “fuel switch” may be why they are so effective at improving survival rates. A larger study involving 100 patients is now underway to determine if standard pacemakers might actually hinder this beneficial metabolic shift.
While some clinicians believe the findings are highly technical and may not immediately overhaul current treatment protocols, others see the research as a promising explanation for the efficacy of resynchronisation therapy. Currently, approximately 12,000 CRT devices are implanted annually in the UK. If further studies confirm that these implants consistently optimise heart fuel consumption, it could lead to much wider use of the technology, offering new hope to those whose conditions are not sufficiently managed by medication alone.
