Scientists from Imperial College London have identified the role of two key microRNAs in the development of broken heart syndrome.
Broken heart syndrome
Broken heart syndrome, also known as Takotsubo syndrome, is a severe but reversible acute heart failure. Estimates suggest that it affects around 2,500 people in the UK every year. It is predominantly seen in post-menopausal women and typically occurs following extreme physical or emotional stress. While coronary arteries are not blocked, the symptoms and complications can be similar to a normal heart attack. The acute mortality rate is 4-5%, also similar to a heart attack.
Researchers do not fully understand what causes Takotsubo syndrome, however sharp rises in adrenaline caused by an acute stress (like bereavement) are known to trigger the loss of movement in part of the heart wall. This then causes the acute heart failure. For surviving patients, recovery can occur within weeks. However, a repeat attack can occur in these patients. Unfortunately, there are no evidence-based treatments for the acute or chronic management of this condition. As a result, understanding the pathogenesis of broken heart syndrome is critical.
In a recent study, published in Cardiovascular Research, researchers explored both human and rat hearts cells to determine how they responded to adrenaline after exposure to two microRNAs. Previous studies have linked miR-16 and miR-26a to depression, anxiety and increased stress levels.
The team found that heart cells treated with the microRNAs were more sensitive to adrenaline and more likely to then develop loss of contraction. Therefore, Takotsubo-like changes were seen at lower levels of adrenaline.
Overall, these findings highlight that miR-16 and miR-26a sensitise the heart to Takotsubo-like changes produced by adrenaline. As these microRNAs have already been linked with anxiety and depression, they could provide a mechanism between long-term stress and the increased likelihood of Takotsubo.
The authors noted that measuring these microRNAs in recovered patients during subsequent periods of stress could help predict the likelihood of recurrence and enable preventative action. In addition, understanding the basis behind sensitisation could allow experts to design other prophylactic pharmacological therapies.
Professor Metin Avkiran, Associate Medical Director at British Heart Foundation, expressed:
“This research is not only a crucial step towards better understanding of this mysterious disease but also could provide new ways to identify and treat those at risk of Takotsubo. We now need further research determine if drugs that block these microRNAs could be the key to avoiding broken hearts.”
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