Groundbreaking Pacemaker Reverses Heart Failure Symptoms

Heart failure symptoms have been reversed in patients with a new pacemaker that changes how the heart is fuelled. Scientists at the University of Oxford and the British Heart Foundation showed they can retrain the heart to burn fat instead of sugar. The trial involved fitting 14 patients with a device called a cardiac resynchronisation therapy (CRT) pacemaker, which switches the heart’s fuel from sugar to fat in just two minutes. In heart failure, the heart no longer uses fat as the main fuel to keep it beating, instead preferring sugar, which can cause stress and further damage the muscle. After six months with the pacemaker, the main pumping chamber of the heart – the left ventricle – had reduced in size by an average of 50 per cent in study participants. The study, which was funded by the British Heart Foundation, also found that the pumping function of the heart – how well it was able to squeeze blood out to the rest of the body – improved by over a third. Professor Neil Herring, professor of cardiovascular medicine at the University of Oxford, said: “The size of the improvement we’ve seen in the hearts in our study in response to CRT is remarkable. “The slowing down of electrical signals in the heart, in some people who have heart failure, may mean the signal for the heart to use fat for fuel is lost, and their heart switches to using glucose instead. “A pacemaker restores the ‘use fat for fuel’ message through fixing the signalling problem as it regulates the heart. This then helps the heart to start to recover. “Through this research, we have identified a new pathway that we can harness to help the millions of people who live with heart failure. This is a vital step to understanding how we can bring forward a new age of therapies.” It is estimated that more than one million people in Britain have heart failure, which can leave patients breathless, tired and struggling with everyday tasks, as their heart cannot pump blood around the body properly. The team set out to investigate whether they could switch the fuel back from glucose to fat, based on evidence that hearts using fat as their energy source have a stronger heartbeat. After being fitted with the pacemaker, people in the study had a mixture of glucose and fat injected into their bloodstream, with an MRI scan showing how the heart took these up. As well as the physical improvements to the heart, patients in the study also reported feeling less breathless after having the pacemaker and were more mobile, while experiencing less pain and discomfort and lower average levels of anxiety and depression. Dr Sonya Babu-Narayan, the British Heart Foundation’s clinical director, said: “This early-stage study involving cardiac resynchronisation devices – specialised pacemakers which coordinate the heart’s pumping chambers to improve its overall function - is intriguing. “The findings suggest these devices can trigger failing hearts to resume using fat as their primary fuel – mirroring the metabolism of healthy hearts. “Although this study involved only a small number of patients, if the results are confirmed in larger, longer-term studies, they could point to new treatment approaches for heart failure that target the heart’s energy source.” Pacemakers are used to correct abnormal electrical signals in the heart, and are typically given to people who have irregular heartbeats, which can be caused by a number of conditions, including heart failure. Unlike traditional pacemakers which work to keep the heart from beating too slowly, CRTs additionally help to re-coordinate the pumping action of the heart to help it beat more efficiently. They can be helpful for people with a type of heart failure where one wall of the heart contracts as the other relaxes, so that blood is not pumped out. The researchers believe CRTs may also restore a signal for the heart to use fat for fuel, which is lost in some people with heart failure, because the electrical signals in their heart, which trigger each heartbeat, have slowed down. When the heart reverts to its correct fuel, it may then start to recover, researchers suspect. According to NHS England, heart failure affects around 920,000 people in the UK. The research was published in the European Heart Journal.