Do Your Genes Raise Your Risk for Sudden Cardiac Death?

The story is all too familiar - a healthy man or woman, with good lifestyle habits and no history of heart trouble, dies suddenly of a heart attack. There was no way to see it coming. It is estimated that this sudden cardiac death kills more than 400,000 people in the United States every year. New genetic research findings suggest that at least 10 gene variations indicate a higher risk of sudden cardiac death. Scientists from the John Hopkins University School of Medicine, the McKusick-Nathans Institute of Genetic Medicine, and other institutions collaborated in analyzing the genomes of 15,842 individuals. The researchers looked at both suspected and unsuspected genetic locations to see what variations could be linked to irregular heart contractions. If the time taken for the heart to contract and then reset for the next beat (the QT interval) is abnormal, it is associated with a heightened risk for sudden cardiac death.

While a past heart attack can cause an irregular QT interval, and thereby up sudden cardiac death risk, a genetic predisposition is a risk factor that is far less apparent. A previous study led to the discovery of a single gene that increases the risk of sudden cardiac death. This later analysis confirmed that finding, and added another nine gene variations that did the same. A number of the genes surprised the scientists by having anything to do with cardiac health at all.

"Almost half were surprising new genes that no one would have guessed as being involved in cardiac biology," explained Dr. Dan Arking of John Hopkins University.

A separate study out of the Massachusetts General Hospital Center for Human Genetic Research and Cardiovascular Center resulted in similar conclusions after viewing more than 13,000 genomes.

"We were very reassured to see such strong replication in two independent studies," said Dr. Christopher Newton-Cheh of the Massachusetts General Hospital.

The goal of the research is to be able to identify people that are at risk for sudden cardiac death despite good health and apparent low risk. At this point, most of those people have no idea that they are genetically predisposed to have serious heart trouble. Unfortunately, these findings do not mean that doctors will be able to predict the cardiac future of people with one, a few, or even all of the 10 genetic variations. In reality, these situations may only alter the QT interval by a millisecond, and not necessarily indicate any real risk. Still, there is potential in the research because of the size of the human sample and the difference that the 10 genetic variations can make together. Hopefully, the area can receive continued attention and grow, eventually allowing healthy people to prevent sudden cardiac death.