In fact, they could be in even more danger of heart disease than their partners.

The researchers have concluded that wives fail to learn the lessons from their spouses' plight, and to adopt a more healthy lifestyle that would minimise their risk of developing heart disease.

The finding flies in the face of the assumption that many doctors make that wives not only look out for their husbands' health after a heart attack, but also improve their own lifestyle as well.

Researchers from the Regional West Medical Center in Scottsbluff, Nebraska, told a meeting of the American Heart Association about their study of 177 men recovering from a heart attack or heart bypass surgery and their partners.

Approximately two months after the heart attack or heart surgery, the patient and his wife separately answered questionnaires on heart disease risk factors.

The researchers analysed the degree to which spouses shared risk factors, either good or bad.

Shared lifestyle

Researcher Lynn Macken said: "Women may be at increased risk if they are married to men with heart disease because of their shared lifestyle.

"In some cases, the women's risk factors were even higher than their husbands', which was particularly alarming because the women tended to be younger than their mates and were not being screened for potential heart disease."

The average age of the women in the study was 58, compared with 62 for the men.

The study found that people who live together often share risk factors for heart disease, such as smoking, lack of exercise, being overweight and eating an unhealthy diet.

The men in the study had an average cholesterol level of 212, while the women had an average level of 226. Anything over 200 is considered too high.

On average, the couples were slightly overweight.

Ms Macken said the stress of having an ill husband could increase the risk of a woman developing heart disease.

But she said there was also evidence that advice that health professionals were giving to heart attack sufferers about adopting a healthier lifestyle was not getting through to their wives.

She said: "They are making the assumptions that they are going to be making these dietary changes.

"Women tend to be forgotten or ignored."

US studies show that although heart disease is the number one killer of both men and women in industrialised countries, many women do not believe they are at risk.

In the UK, heart disease is the biggest killer of women, despite the protective effect of female sex hormones up until the menopause.

Women's chances of developing the disease rise sharply as they pass through the menopause, and are associated with risk factors such as obesity, smoking, and high levels of certain types of cholesterol.

The British Heart Foundation welcomed the research.

In a statement, it said: "All heart patients should be encouraged to make healthier lifestyle changes as part of their rehabilitation and recovery, but a supportive family environment can help make these adjustments easier.