Two molecules associated with high stress levels have been implicated in the development of broken heart syndrome, a condition that mainly affects post-menopausal women and is usually brought on by severe stress, such as the loss of a loved one.
The syndrome, formally known as takotsubo cardiomyopathy, is characterised by weakening of the heart’s main pumping chamber and was first identified in 1990 in Japan. It looks and sounds like a heart attack and is consequently often confused for one.
Affecting an estimated 2,500 people in the UK each year, the syndrome also carries a risk of complications similar to that of an actual heart attack. It is unclear what causes takotsubo, but sharp spikes in adrenaline caused by acute stress like bereavement, car accidents, earthquakes and even happy events such as weddings are understood to drive loss of movement in part of the heart wall, which then precipitates the acute heart failure.
Two molecules – called microRNA-16 and microRNA-26a — that are linked to depression, anxiety and increased stress levels had previously been detected in the blood of takotsubo patients. Researchers assessed the impact of exposing cells from human hearts (taken from organs that were unsuitable for transplants) and rat hearts to the two molecules.
Afterwards, both sets of heart cells were more sensitive to adrenaline, they wrote in the journal Cardiovascular Research.
In patients with takotsubo, the bottom of the heart stops beating, and the top of the heart beats more, said the lead study author, Dr Liam Couch from Imperial College London. “Basically, we found the exact same thing happens when we increase the exposure to the molecules [in an experimental setting]. It reproduced exactly what happens in takotsubo, so it made it more likely for the takotsubo to occur.”
Overall, the findings appeared to link long-term stress and the dramatic takotsubo response to a sudden shock.
However, the problem is that it is not possible, for now, to diagnose takotsubo in patients before it happens, making it difficult to test whether these molecules are elevated in real-life cases, Couch explained.
“But if we know someone’s had takotsubo, theoretically we can measure these molecules, and then predict if they’re likely to have it again, because there’s a one in five chance that they could have it again,” he said.
Joel Rose, chief executive of the charity Cardiomyopathy UK, said the study provided important insights on a less well known and poorly understood form of cardiomyopathy. “It has the potential to improve our understanding of who may be more susceptible to developing the condition and subsequent improve our ability to manage its impact,” he said.
Further research is needed, said Prof Metin Avkiran, the associate medical director at the British Heart Foundation, to “determine if drugs that block these microRNAs could be the key to avoiding broken hearts”.