Why a ‘broken heart’ can be fatal

Soul singer Al Green posed an age-old question in his 1972 hit How Can You Mend a Broken Heart - but now scientists believe they may soon have the answer.

New research has revealed why stressful events such as divorce or bereavement can trigger takotsubo cardiomyopathy, also known as broken heart syndrome. Affecting an estimated 2,500 people in the UK each year, mostly women, it occasionally proves fatal.

The condition “causes the left ventricle of your heart to change shape and get larger” until it begins to resemble the narrow-necked Japanese octopus trap after which takotsubo is named, explains the British Heart Foundation, which funded the Imperial College London (ICL) study.

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This “weakens the heart muscle and means it doesn't pump blood as well as it should”, causing heart attack-like symptoms including chest pain and shortness of breath, says the charity.

Why the syndrome strikes some people but not others has been a “longstanding medical mystery”, writes The Times’ science correspondent Rhys Blakely. In about 70% of cases, a “stressful trigger” is identified, he continues. “About 50% will result in acute complications, while about 10% who have had takotsubo syndrome once will have another episode.”

But although no treatments are currently available to prevent further attacks, the ICL researchers “have now found that increased levels of two types of molecule in the blood, linked to stress and anxiety, signal a heightened risk”, Blakely reports.

These molecules - called microRNA-16 and microRNA-26a - regulate how genes are decoded to produce proteins inside cells. Experiments involving human and rat heart cells found that the molecules appeared to make the cells more likely to stop functioning properly when exposed to adrenaline.

The study findings, outlined in a paper in the journal Cardiovascular Research, suggest that “longer-term stress followed by a dramatic shock could trigger the effects seen in broken heart syndrome”, says The Telegraph.

Separate recent research by Harvard Medical School scientists also found links between activity in the amygdala, “a brain region involved in stress response”, and an increased risk of takotsubo, The Scientist reports.

Experts say the next goal is to develop a blood test or drugs to help identify and prevent cases in high-risk patients.

Sian Harding, professor of cardiac pharmacology at ICL, said: “Takotsubo syndrome is a serious condition, but until now the way it occurs has remained a mystery. We don’t understand why some people respond in this way to a sudden emotional shock while many do not.

“This study confirms that prior stress, and the microRNAs associated with it, can predispose a person to developing takotsubo syndrome in situations of future stress. Stress comes in many forms, and we need further research to understand these chronic stress processes.”

BHF medical director Professor Metin Avkiran added that studies to “determine if drugs that block these microRNAs could be the key to avoiding broken hearts”.