Bob and Mary Granfeldt are true soulmates.

They were born 16 days apart, began dating when they were 15 and will celebrate their 48th wedding anniversary this year.

"My life started when I met him," Mrs. Granfeldt said.

"We've been each other's life," said Mr. Granfeldt, a retired Episcopal priest.

That relationship could be keeping them alive much longer. Heart patients in good relationships -- like the Granfeldts -- tend to do much better than those in bad relationships or who are alone, said Mindy Gentry, the medical director for the Women's Cardiovascular Program at Medical College of Georgia Hospital.

One study found that those who had a heart attack and no close confidante to rely on had twice the risk of further cardiac problems. It is something Dr. Gentry sees all of the time.

"And because we know that they tend to do worse than people who have a good support system, we absolutely talk to them about trying to find somebody, some sort of confidante, whether it is somebody at their church or a neighbor, somebody that they can count on to help them get through stuff," she said.

It's not just social -- feeling isolated and alone can trigger stress in the body that can cause physical changes that worsen cardiovascular disease, Dr. Gentry said.

"Higher blood pressure, higher heart rate, more strain on the heart itself," she said. "So having a good support system, a good partner is important to help blunt some of those effects."

Those without support are also more likely to develop depression after a heart attack or surgery, which can have its own bad effects, Dr. Gentry said.

"They die more frequently, they have higher incidences of recurrent heart attacks. They just tend to do a lot more poorly," she said.

"Even people who are on good medical therapy, who are on good medicines, even when you correct for that, there is still a big difference between people that have good support relationships and those that don't," she said.

You don't have to tell the Granfeldts. She has a "terrible family history" of heart disease and has had an irregular heartbeat; he has had a heart valve replaced. But at 67, they and their relationship are in good shape. Patience is key, as is communication and keeping things in perspective, they said.

"We've been married all these years and we've never had a fight or bickered about money," Mrs. Granfeldt said. "We both understand these are little things."

"We've been talking about these things since we were 15 years old," Mr. Granfeldt said.

It's no accident that a good relationship ensures good health, they said.

"It helps everything," Mrs. Granfeldt said. "Life just gets easier."

"Loving helps," Mr. Granfeldt said.

Perhaps more than they know.