Vishvajyth Ponnambalam
A team of interdisciplinary researchers have found that radiation therapy could potentially improve heart function in patients suffering from heart failure. But what exactly is heart failure and what causes it?
Treatment is usually necessary for the lifetime of the patient
Heart failure is a debilitating cardiovascular disease in which the heart isn’t able to pump blood around the body as effectively as it should be. It is a progressive disease and can occur in patients of any age, although older people are more commonly affected. In the UK, over 1 million people are estimated to be afflicted by the disease, with over 200,000 new diagnoses reported each year, illustrating the burden that heart failure puts on the NHS. Heart failure usually occurs due to an existing cardiovascular disease such as coronary heart disease or hypertension, however, other conditions such as alcohol overconsumption, obesity and anaemia can also lead to heart failure.
Low doses of radiation therapy can benefit heart function
So, what are the current treatments available for patients suffering from heart failure? Other than lifestyle changes and drug treatments such as Angiotensin Converting Enzyme Inhibitors (ACEIs), beta blockers and diuretics, common treatments include medical devices to control the rhythm of the heart and heart transplant in certain cases. Treatment is usually necessary for the lifetime of the patient, and even with treatment the health of the heart is unpredictable and limits the activities patients suffering from heart failure can do. Due to these factors, there is a constant search for new treatments and potential for improving or reworking existing treatment to provide patients with better outcomes.
One recent study from cardiologists and radiation oncologists at the Washington University School of Medicine in St. Louis put forth the idea of using radiation therapy, a standard treatment for cancer patients, to improve the function of the heart in the case of heart failure. The study implies that low doses of radiation therapy can benefit heart function by reducing the number of immune cells in cardiac muscle cells.
In the heart, the tissue is scarred by inflammatory immune cells
Radiation therapy has been used to treat other heart conditions in humans such as ventricular tachycardia and arrhythmias, by targeting a specific area of the heart. It was found that from this therapy, low doses of radiation were delivered to the rest of the heart. When the effects of this radiation exposure were analysed, there was a clear improvement in heart function.
The researchers followed three groups of mice with heart failure who were subjected to low dose radiation. The study found results similar to that of patients with ventricular tachycardia – an improved heart function, in particular the left ventricle. Mice with progressive heart failure also displayed extended survival.
There is the potential for damage to occur in the cardiac tissue if the dosage of radiation is incorrect
So why does an anti-cancer treatment seem to work for a heart condition? Radiation therapy consists of killing rapidly dividing cells, such as cancer cells. In the heart, the tissue is scarred by inflammatory immune cells, which increase in number during heart failure, leading to a deteriorating heart condition. But the mice which received radiation therapy saw a decrease in immune cells dividing and growing, hence leading to sustained heart tissue.
This is only the beginning for the team at St. Louis, where plans to test out the validity of their arguments in human hearts are underway, but because of the novelty of this treatment strategy, there are justifiable concerns regarding the safety and efficacy of this treatment method. Firstly, there is the potential for damage to occur in the cardiac tissue if the dosage of radiation is incorrect. The adequate dosage can differ from person to person, so how can we ensure that a low dose in one person is considered low in another?
Furthermore, thoracic radiation therapy has actually been found to induce heart failure in many studies of lung, breast, and oesophageal cancer. because of this. patients suffering from multiple conditions may not benefit from this treatment, which is often the case for elderly people.
Overall, the concept of radiation therapy for heart failure treatment is yet to be explored in its entirety, and until then, a clear verdict regarding its benefits can be given. In recent years polypharmacy (using multiple medications to treat a condition) and drug repurposing (a drug designed for one disease used to treat another) have started to become more and more common, so it is not surprising that this new treatment brings hope for providing a better treatment to patients.
Vishvajyth Ponnambalam
Featured image courtesy of Towfiqu barbhuiya via Unsplash. Image license found here. No changes were made to this image.
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