Women are less likely to be resuscitated and survive a cardiac arrest than men, a new study has found.

The research, published in the European Heart Journal, found women and men received unequal treatment when suffering a cardiac arrest.

It found women who have a cardiac arrest outside the hospital setting are less likely to receive resuscitation from passersby and more likely to die than men.

The disparity in treatment they received in the community was found to be partly to do with the fact that people did not recognise that women who had collapsed were having a cardiac arrest – prompting delays in calling the emergency services and delays in delivering resuscitation treatment.

Cardiac arrest takes place when the heart goes into an irregular rhythm and then stops beating entirely. It is different from a heart attack.

Under the skin – best of the British Heart Foundation 2018 image prize Show all 10 1 /10 Under the skin – best of the British Heart Foundation 2018 image prize Under the skin – best of the British Heart Foundation 2018 image prize Subarachnoid vessels The runner-up image came from Matt MacGregor Sharp, a PhD student at the University of Southampton. The super-high resolution image shows a normal artery at the surface of a rat’s brain and was taken with a powerful scanning electron microscope. These ‘subarachnoid vessels’ supply blood to the brain and also act like a drain to remove toxic waste products. Matt Macgregor’s team are trying to show that failure to remove waste by these vessels is one of the underlying causes of vascular dementia. The researchers took the image using a technique called ‘freeze fracture’, where tissue or cell samples are frozen and then split apart to reveal the hidden layers within the sample so they can be studied in extreme detail. Sitting above the brown brain tissue, the artery appears blue, and its surrounding layer, the pia mater, is shown in purple. Matt MacGregor Sharp, University of Southampton, British Heart Foundation - Reflections of Research Under the skin – best of the British Heart Foundation 2018 image prize Explosive beginnings Winner: Endothelial cells line all blood vessels in the body, forming a barrier between the circulating blood and the vessel wall. They also help to protect blood vessels from damage and release important chemical messengers which help to control blood pressure. The winning researcher, Courtney Williams, is a Masters student and PhD candidate at Leeds University. Her lab are developing new ways to map the growth of new blood vessels within their surrounding landscape in 3D. 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Abdullah Obaid Khan, University of Birmingham, British Heart Foundation - Reflections of Research Under the skin – best of the British Heart Foundation 2018 image prize Cardiac collagen web - Shortlist This colourful image shows the web-like, network of the smallest blood vessels in the heart – the microvessels. Magenta marks the outer collagen layer of the vessels; while orange marks their inner lining and blue the cell nuclei. Dr Neil Dufton, Imperial College London Dr Neil Dufton, Imperial College London, British Heart Foundation - Reflections of Research Under the skin – best of the British Heart Foundation 2018 image prize Heart to Heart - Shortlist This piece shows four ventricles (from a mouse) arranged into the shape of the hearts four normal chambers. The researchers have used fluorescent markers to recognise certain proteins and created the image using of hundreds of images assembled together. 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Dr Svanhild Nornes, University of Oxford Dr Svanhild Nornes, University of Oxford, British Heart Foundation - Reflections of Research Under the skin – best of the British Heart Foundation 2018 image prize Calcium reef - Shortlist This image shows calcium in blood vessel cells from people who have high blood pressure and resembles Australia’s Great Barrier Reef. Dr Rheure Alves-Lopes, University of Glasgow Dr Rheure Alves-Lopes, University of Glasgow, British Heart Foundation - Reflections of Research Under the skin – best of the British Heart Foundation 2018 image prize Budding blood vessels - Shortlist This image shows the growing blood vessels in the mouse retina. In red you can see all the blood vessels and in yellow/green you can see the blood vessels that are actively growing (a process called sprouting). PhD candidate Kira Chouliaras, University of Oxford Kira Chouliaras, University of Oxford, British Heart Foundation - Reflections of Research

Dr Hanno Tan, a cardiologist based at the University of Amsterdam, said: “We found that the worse outcome in women is largely attributable to the fact that women had about half the chance of having a shockable initial rhythm compared to men.”

Dr Tan, who led the research, and his team analysed data from all resuscitation attempts made by emergency services between 2006 to 2012 in one province in The Netherlands. They identified 5,717 out-of-hospital cardiac arrests treated during this period – 28 per cent of which occurred in women.

They found women were less likely than men to receive a resuscitation attempt by a bystander – 68 per cent rather than 73 per cent. The figure was virtually the same even when someone witnessed the collapse.

Survival from the time of the cardiac arrest to admission to hospital was lower in women – 34 per cent versus 37 per cent. Women were less likely to survive from admission to discharge – 37 per cent rather than 55 per cent.

Overall, the chances of women surviving to be released from hospital was around half that of men. Researchers consider this is largely explained by the lower rate of shockable initial rhythm in women – 33 per cent versus 52 per cent – and found several reasons that might explain this difference.

Shockable initial rhythm is the heart rhythm recorded when someone with cardiac arrest is connected to an electrocardiogram machine. It is highly fast – often more than 300 beats a minute – and chaotic. Death takes place within minutes unless the heart can be shocked back to a normal rhythm by means of an electrical current from a defibrillator.

Dr Tan said that even when they adjusted their findings to take account of pre-existing diseases and factors relating to the way in which resuscitation was provided by professionals – for example how long it took for the ambulance to arrive – they still found women were half as likely as men to have shockable initial rhythm.

“This suggests that the lower proportion of women with shockable initial rhythm is not fully explained by women being more likely to have pre-existing diseases or by different resuscitation factors, and that other, as yet undiscovered, factors also play a role,” he added. “However, when we looked only at cardiac arrest victims who did have a shockable initial rhythm, we found there was no difference in overall survival rates between men and women.”

Researchers said a potential reason why fewer women have shockable initial rhythm by the time the emergency services get to them may be because fewer women than men tended to have a cardiac arrest when there were other people around to see it happen. They noted this could be linked to there being more elderly women living on their own than men and because the symptoms of a heart attack – one of the most common causes of cardiac arrest – might not be recognised so rapidly in women.

Dr Tan said: “People may be less aware that cardiac arrest can occur as often in women as in men, and the women themselves may not recognise the urgency of their symptoms. Women may have symptoms of an impending heart attack that are less easy to interpret, such as fatigue, fainting, vomiting and neck or jaw pain, whereas men are more likely to report typical complaints such as chest pain.”

He added: “As cardiac arrests occur most often outside the hospital setting in the general population, much can probably be gained by raising awareness in society that cardiac arrest is as common in women as in men but may have different symptoms. Given the short window available to save the life of the patient, every minute in this early phase counts; help, if only a call to the emergency number by a layperson, is crucial. So, raising awareness through public campaigns could make a big impact on women’s survival.”