People at genetic risk for heart disease can decrease chances of heart attack by getting active

A new study examines how physical activity can help reduce heart health risks.

A new study says, quite clearly, no.

Many people likely know that staying active and physically fit, in addition to other healthy behaviors, can prevent heart disease.

Heart disease is the number one cause of death of men and women in the United States -- it kills more than 700,000 people yearly. Heart attacks, heart failure, stroke and abnormal heart rhythms such as atrial fibrillation are all under the “heart disease” umbrella, and most of these conditions involve narrowed or blocked blood vessels.

A new study published in the American Heart Journal, Circulation, looked at almost 5 million men and women of different ages and races in Europe and followed them over the course of about six years.

People in the study were deemed as a high, moderate or low risk for heart disease based on their family history.

The results were surprising. The most active people -- even considering their other high-risk factors -- saw their risk of having a heart attack, stroke or atrial fibrillation drop by almost 50 percent. This was true of those with even a low or moderate genetic risk for heart disease.

However, exercise is the most cost-effective way to help prevent heart disease.

Dr. Roshini Malaney is a cardiology fellow at Stony Brook University Hospital working with the ABC News Medical Unit.