Men with angina are much more likely than women to develop further serious heart problems, a study suggests.
Researchers found male patients were twice as likely to have a heart attack and almost three times as likely to suffer a heart disease-related death.
Angina, a type of chest pain, is common and can be the first sign of heart disease - but the risks are unclear.
The study of UK patients, led by the National University of Ireland, Galway, appears in the British Medical Journal.
Angina is caused by insufficient supply of blood to the heart muscle.
Recent estimates suggest that 4.8% of men and 3.4% of women aged over 16 in England have angina.
In Scotland, the figures are higher: 6.6% of men and 5.6% of women.
The Irish team identified 1,785 patients in Scotland who were diagnosed with angina between January 1998 and December 2001, and tracked their progress for five years.
They found being male, older and a smoker was associated with an increased risk of having a heart attack.
The same factors - along with obesity - were also associated with a higher risk of dying from heart disease.
Men were also more likely than women to undergo angioplasty to open up blocked arteries, or to have coronary artery bypass surgery.
Lead researcher Dr Brian Buckley said the reasons why men appeared more at risk were unclear.
Some believe the problem could be that men are less likely to follow medical advice following diagnosis.
Others suspect that men do not go to their doctor until their condition is more advanced.
Women are also thought to receive some protection from the sex hormone oestrogen.
Dr Buckley said: "We need to look at what the hell is happening here rather more closely than we have in the past.
"Hopefully, our study has demonstrated that men are at more risk -so indisputably, that more research will take place looking at why."
He said the main message from the study was that people with angina should take steps to improve their lifestyle to minimise risk of more serious disease.
He said: "If you are diagnosed with angina, you should not panic - it won't necessarily end up in a heart attack - but you ought to take what the doctor says to you seriously, both in terms of taking medication and adopting a healthier lifestyle."
Dr Mike Knapton, associate medical director of the British Heart Foundation, said the study was important because it was based on large numbers of people living in the community, rather than in a hospital setting.
He said: "It confirms that smoking and being obese greatly up your risk of dying from heart disease.
"This is good news for people living with angina, as it shows that it's never too late for them to change their lifestyles, or to stop smoking."
The research was carried out in collaboration with the University of Aberdeen.