Heart Rate Linked to Sudden Death — Danger Signs: Too Fast During Rest; Too Slow During Exercise

Scientists in France think they’ve figured out how to predict which people are at risk of dropping dead suddenly from a heart attack. They found that those whose hearts beat too fast during rest and too sluggishly during exercise have a higher chance of sudden cardiac death.

The research, believed to be the first on sudden death in healthy people, relied on simple stress tests like the ones often given to people with heart problems.

Experts said the findings don’t mean healthy people should have routine stress tests. But they said that when heart patients get the tests, doctors should study the heart rate pattern for signs of trouble and not just look for evidence of blocked arteries as most do now.

“We know there are people who are walking time bombs,” said Dr. Michael S. Lauer, a staff cardiologist at the Cleveland Clinic who was not involved in the latest study but who also researches stress tests and how patients fare over time. While there’s no proof early intervention prevents premature deaths in such people, he said, “I would fix absolutely everything that can be fixed.”

That would include putting patients on medicines such as aspirin and drugs to control blood pressure and cholesterol, and starting them on an exercise program to tone up the heart.

The latest study, in today’s New England Journal of Medicine, found the risk of sudden death was about four times higher than normal in men whose hearts beat fast while resting or didn’t speed up as much as they should during exercise. Likewise, sudden death was twice as likely in men whose heart rates didn’t slow down enough in the minute after exercise ended, compared with men with normal shifts in their heart rate.

Sudden death occurs when a heart attack, or sometimes an abnormal rhythm, stops the heart. It strikes people as young as their 30s and 40s, and is responsible for 5 percent to 10 percent of all U.S. deaths, or roughly 350,000 to 500,000 deaths a year.

The results probably also apply to women, said Lauer and Dr. Daniel Shindler, a cardiologist and professor at Robert Wood Johnson Medical School.