TORONTO — It seems a happy heart is often a healthier heart and may promote longer life.

At least that's the conclusion of a U.S. study of coronary artery bypass patients, which found that those who were happily married were more than three times as likely to be alive 15 years after their surgery as their single, divorced or widowed counterparts.

"There is something in a good relationship that helps people stay on track," said lead author Kathleen King, a professor emerita from the School of Nursing at the University of Rochester.

The researchers followed 225 people who had bypass surgery between 1987 and 1990. They asked married participants to rate their relationship satisfaction one year after surgery, then checked how many subjects had died 15 years following their operations.

They found that 83 per cent of happily wedded wives were still alive, compared with 28 per cent of women in unhappy marriages and 27 per cent of unmarried women. The survival rate for contented husbands was also 83 per cent, but even the not-so-happily married fared well: men in less-than-satisfying unions enjoyed a survival rate of 60 per cent, much higher than the 36 per cent rate for unmarried men.

"Married women lived longer than unmarried women after surgery and married men lived longer than unmarried men after surgery," King said from Rochester. "But then when you go and look at whether or not they were satisfied in their marriage, for men it didn't make as big a difference if they were satisfied or not satisfied.

"For men, just the fact of them being married gave them a benefit. But for women, it was more powerful if they were highly satisfied in their marriage."

While unhappy marriages provide virtually no survival bonus for women, satisfying unions boosted a wife's survival rate almost fourfold, say the researchers, whose paper is published online Monday in Health Psychology, an American Psychological Association journal.

"Wives need to feel satisfied in their relationships to reap a health dividend," co-author Harry Reis, a professor of psychology, said in a statement. "Other research has shown that women are more physiologically sensitive to relationship distress than men, so an unhappy marriage can take a greater toll on their health."

It's long been recognized that bypass surgery to get around blocked coronary arteries significantly reduces the risk of a heart attack, but it doesn't automatically halt the progress of the disease that made the surgery necessary in the first place.

"We know that for most patients, (bypass) graphs are a temporary patch, even more susceptible to clogging and disease than native arteries. So, it's important to look at the conditions that allow some patients to beat the odds," said King, a nurse who has specialized in cardiac patient care for 40 years.

"If you don't change your health habits, those bypass grafts get coronary artery disease. I think being married, especially if you're happily married, you have somebody who will encourage you to change your behaviour -- to exercise more, to watch your diet, to stop smoking, all those sorts of traditional risk factors."

From an emotional perspective, good long-term relationships create a reciprocal effect, she added. "You're more willing to give advice, but the patient -- the person who had the surgery -- is more willing to take it.

"The person who really needs to change their behaviour does so because they care enough about staying in the marriage to be there."

Dr. Andrew Pipe, who specializes in preventive and rehabilitation medicine at the University of Ottawa Heart Institute, said the study affirms previous evidence showing that people who have minimal levels of stress and feel content generally fare better than those in the opposite situation.

"We know that stress of any kind, whether it's the stress that occurs in a dysfunctional relationship or a stressful marriage, the stress that can occur as a consequence of workplace environments, poverty, all of those sorts of things, do translate to the release of chemical messengers ... that can have an impact on cardiovascular health," Pipe said from Ottawa.

Increased cascades of these chemicals, including the stress hormone cortisol, can lead to higher cholesterol levels and inflammation that damages blood vessel walls, he said.

While the study suggests that a satisfying union appears to translate into improved survival following bypass surgery, the reality is that not all patients are in long-term relationships.

"I think in terms of health-care providers, the message is how much attention do you pay into making sure people are doing what they need to be doing if they're living alone," said King. "The problem with that is that helps in the short-term, six months to a year after surgery. But after that, that kind of support system is not around."

That's why it's important for singled, divorced or widowed patients to reach out for -- and accept --other means of receiving the kind of encouragement needed to maximize longevity, said Pipe.

"Reach out to your family and friends and ask for support and understanding, and enjoy the support and the care that is provided if you are single. They will have beneficial effects on your recovery and ultimately your long-term health."