Heart rate treatments could be used to improve heart function

A recent study by Birmingham researchers, delivered through the National Institute for Health and Care Research (NIHR) Birmingham Biomedical Research Centre (BRC), has shown that treatments used to control heart rate could be used to help heart function in patients with atrial fibrillation and heart failure.

Atrial fibrillation is a common heart condition that leads to an irregular and often rapid heart rate. Atrial fibrillation can reduce heart function, resulting in patients developing a condition known as heart failure. Heart failure happens when the heart either doesn’t pump or relax as well as it should. As a result, the body does not receive enough oxygen, causing patients to develop symptoms such as breathlessness, dizziness and swelling in their feet and ankles. The number of patients with both atrial fibrillation and heart failure is increasing exponentially, making it important to define effective therapies.

Heart rate treatments

Recently, a team of researchers from Birmingham carried out the RATE-AF trial, funded by the NIHR, which compared two treatments used to control heart rate, called beta-blockers and digoxin. This trial revealed that digoxin led to fewer adverse events, including lower rates of hospital admission and general practice reviews for heart health. Digoxin was also found to have greater cost-effectiveness.

Researchers have carried out a sub-study within the original trial, investigating whether there was a difference in how these two treatments affected heart function specifically.

Effectiveness for heart function

The 160 patients who participated in the randomized study were either given digoxin or a beta-blocker called bisoprolol daily on a 1:1 ratio. They all had an ultrasound scan of the heart, called an echocardiogram, before starting their treatment and subsequently after 12 months of their treatment. This measured how well the heart pumped and relaxed at each of these points.

“This study supports the use of low-dose digoxin in this patient group to improve heart function with a greater improvement seen in patients with heart failure and a preserved ejection fraction.”

Dr Karina Bunting, British Heart Foundation Career Development Research Fellow, University of Birmingham

The results of the study revealed that digoxin improved heart pump function in all patients with atrial fibrillation and heart failure. In patients whose atrial fibrillation and heart failure was caused by a heart which is unable to relax normally, digoxin was found to improve the pump function of the heart more than beta-blockers. Additionally, digoxin was found to cause fewer side effects than beta-blockers and improved symptoms related to atrial fibrillation and heart failure to a greater extent.

Dr Karina Bunting, British Heart Foundation Career Development Research Fellow at the University of Birmingham, and a researcher within the NIHR Birmingham BRC Thrombo-inflammation research theme, said: “There is limited data to guide doctors on what treatment to give patients with atrial fibrillation and heart failure, particularly in those with a preserved ejection fraction.

“This study supports the use of low-dose digoxin in this patient group to improve heart function with a greater improvement seen in patients with heart failure and a preserved ejection fraction, alongside improvement in symptoms, reduced strain on the heart and significantly fewer adverse events when compared to beta-blockers.”

Researchers hope that the results of the study may continue to inform future treatment for patients with atrial fibrillation and heart failure.