Doctors are failing to spot thousands of heart attacks in women, a major study has revealed.
It shows that misdiagnosis rates are 50 per cent higher than for men.
Experts say the 'alarming' disparity might be explained by doctors - and women - assuming that heart disease affects only unhealthy middle-aged men.
As a result, symptoms in female patients can be dismissed as indigestion, muscle pain or anxiety. Delayed treatment drives up death rates by as much as 70 per cent.
The records of 600,000 British patients were analysed for the study by the University of Leeds. They suggest that around 24,000 heart attacks in women are initially misdiagnosed each year.
Dr Chris Gale, a consultant cardiologist at the university, said his team's research showed the need to challenge preconceptions.
"Typically, when we think of a person with a heart attack, we envisage a middle aged man who is overweight, has diabetes and smokes.
"This is not always the case. Heart attacks affect the wider spectrum of the population - including women."
Experts say another mistake is to assume that a heart attack strikes suddenly, with the victim clutching their chest and keeling over.
In fact the process is more gradual with patients often complaining of nausea and an aching chest, jaw or arms.
Rapid treatment is essential - nearly half of salvageable heart muscle is lost in the first hour. Yet only one in four victims get treated within this short window.
Dr Gale's team examined data gathered over nine years at 243 NHS hospitals in England and Wales between April 2004 and March 2013. They found that 198,534 men and women - a third of all heart attack victims - were initially misdiagnosed.
But women were 50 per cent more likely than men to have their symptoms missed, according to the study published in the European heart journal Acute Cardiovascular Care.
"This research clearly shows that women are at a higher risk of being misdiagnosed following a heart attack than men," Dr Gale told the European Society of Cardiology congress in Rome.
Some 69,000 women have a heart attack in the UK every year, compared with 119,000 men. But women are more likely to die as a result of the attack.
A separate study based on Swedish data, also presented by Dr Gale at the conference, suggested women were between 13 per cent and 53 per cent more likely than men to die following a heart attack.
Dr Gale said one issue was that women had different symptoms to men - they are more likely to complain of indigestion, palpitations or a 'funny turn'.
Female victims also more likely to be elderly and suffer from other complications such as diabetes, which makes spotting the problems harder.
But Dr Gale said doctors and patients alike have to be taught that heart attacks can strike women as well as men - and can present a variety of different symptoms.
"It's not necessarily 20 minutes of crushing chest pain, it may be some chest pain and a funny turn, or a feeling of palpitations and a bit of chest pain," he said. "It can be difficult but we have to work in an urgent environment and we have to work quickly. Heart attack care is all about speed."
His team found that women who were initially diagnosed with a heart attack had a 2.5 per cent of dying within 30 days.
If they were initially misdiagnosed, their risk of death went up 70 per cent, to 4.2 per cent. For men the figures were 1.8 per cent and 3.2 per cent.
Previous research shows women are less likely to receive standard medications for heart disease and less likely to get on rehabilitation programmes. Dr Mike Knapton, of the British Heart Foundation, which funded the research, said it gave a better understanding of the experiences of both men and women when they are diagnosed as having suffered a heart attack.
"The difference is alarmingly high," he added.
"This new study highlights the current scale of the issue and confirms more research is urgently needed into tests that will enable earlier and more accurate diagnosis of a heart attack, particularly in women."
An NHS England spokesman said survival rates for heart attacks were the best they had ever been and swift diagnosis and treatment were key.
He added: "We are working hard to continually improve tests for accurately diagnosing heart attacks in both men and women so that correct treatment can begin without delay, ensuring the best possible recovery for patients.
"We are also working to increase awareness of signs and symptoms."