In children, can being treated for cancer have consequences for the heart - namely, cardiac arrythmias? A new study by researchers at Université de Montréal and its affiliated CHU Sainte-Justine Azrieli Research Centre provides some answers.
Published last fall in the International Journal of Cancer, the study looks at the long-term and often undiagnosed chemotherapy complications of treatments for acute lymphoblastic leukemia (ALL), the most common type of pediatric cancer.
Advances in medicine have led to a significant increase in the survival rate of children with ALL: now close to 85 percent.
Nevertheless, a large number of young cancer survivors develop health problems following chemotherapy treatments. These can include cardiovascular complications such as acquired long QT syndrome (aLQTS), a type of heart arrhythmia caused by problems with the heart's electrical system.
Fast and uneven heartbeats
While this syndrome doesn't appear in the heart's structure, the person may nonetheless experience fast and uneven heartbeats caused by exercise or stress. It may sometimes cause sudden fainting and seizures, and increases the risk of developing potentially deadly events such as cardiac arrest.
In their study, the UdeM researchers had approximately 200 childhood ALL survivors do a treadmill stress test and found that 70 per cent of those who had an abnormal QT during the test had no anomalies at rest.
In other words, a significant number of the test participants were unaware that they were at risk of developing a heart condition. Moreover, the study showed that 10 per cent of these participants were considered to have long QT, a severe form of the syndrome.
"Chemotherapy leads to change in cardiac muscle cells," said cardiologist Cecilia Gonzalez Corcia, one of the study's co-authors. "These changes may not always be visible at rest, but can nonetheless cause anomalies when the heart muscles are under pressure, such as during intense physical exercise."
The study is the first to identify and characterize childhood ALL survivors with possible aLQTS using maximal exercise testing.
A standardized test is needed
"Our results show the importance of including exercise testing in cardiological follow-ups of pediatric cancer survivors, in particular a standardised cardiopulmonary exercise test to be completed in addition to electrocardiography and electroencephalography tests," said doctoral student Audrey Harvey, the study's first author.
The study also emphasizes the need for long-term medical follow-ups, especially for cancer survivors who received higher doses of chemotherapy or who underwent such treatment over a long period of time, or even for those who wish to practice a sport after their remission, she said.
Although such tests are not yet officially recommended, the UdeM researchers hope their study will help build consensus among experts on how to use them to better prevent the onset of heart problems and improve diagnosis and the quality of life of young cancer survivors.
About this study
"Uncovering possible silent acquired long QT syndrome using exercise stress testing in long-term pediatric acute lymphoblastic leukemia survivors," by Audrey Harvey et al., was published Sept. 8, 2024 in the International Journal of Cancer.
