If heredity puts you at higher risk for a heart attack, maintaining a healthy lifestyle can bring that risk down dramatically, below the risk faced by some people whose genes would normally protect them from heart disease, according to a new analysis of more than 55,000 people.
“We were a little surprised by how much you could offset your inherited risk by adhering to a healthy lifestyle,” said Dr. Sekar Kathiresan, chief author of the new study, presented at an American Heart Association meeting on Sunday and published online simultaneously by the New England Journal of Medicine.
The 20 percent of the population with the highest genetic risk had a 5.1 percent chance of having a heart attack over 10 years if they practiced a healthy lifestyle. That was lower than the 5.8 percent likelihood among people with the lowest genetic risk but who had an unfavorable lifestyle.
But the study also confirms that genes play a key role in the risk of heart attack, regardless of lifestyle.
Among people who practiced heart-healthy habits, the odds of a heart attack among people with a low genetic risk was 3.1 percent over 10 years compared with 5.1 percent when their genetic risk was high.
Among people who were obese, didn’t exercise, smoked, and didn’t eat a healthy diet, the heart attack rate when the genetic risk was low was almost double (5.8 percent per decade) the baseline risk of 3.1 percent. It jumped to 10.7 percent when their genetic risk was high.
Because people can’t alter their genetic profile and their only option is to change their lifestyle, the good news from the study is that making those lifestyle changes can have a real impact, said Kathiresan, director at the Center for Human Genetic Research at Massachusetts General Hospital in Boston.
“Many physicians and patients assume if you have a strong inherited risk, you’re destined to have a heart attack; you can’t change the hand that’s dealt to you in terms of genetics,” he said by phone. “But if you adhere to a healthy lifestyle, you can reduce your risk by maybe 50 percent.”
More than 55,000 people from four large databases were included in the study. To rank their inherited risk of a heart attack, the researchers tested them for 50 genetic variants linked to a higher risk of cardiovascular disease.
People who met three or four of the healthy criteria were classified as living a favorable lifestyle. Those who met one or none were classified as having an unfavorable lifestyle.
“This is the first study to look at the interplay of both genetics and lifestyle, and how much you could offset your genetic risk with an optimal lifestyle,” said Kathiresan.
Doctors have known since the late 1930s that the risk of heart disease is partly inherited. In recent years, genetic studies have refined the risks. The degree to which lifestyle changes, including quitting smoking, can reduce that risk has remained uncertain.
Among risk factors that people could alter, the researchers found that not smoking cut the overall heart attack risk by 44 percent, not being obese reduced it by 33 percent, getting regular physical activity dropped it by 16 percent and maintaining a healthy diet made a heart attack 9 percent less likely.
“People react to genetics in one of two ways,” said Dr. Kathiresan. “They react with fatalism, saying, ‘I don’t have any control. Why not go out living high?’ The other way is, “I get religion and make a big set of changes.’ For the first approach, that’s not needed. DNA is not destiny. You still have some control. You can cut that inherited risk by more than half.”