Milwaukee ? The left main coronary artery is one of the worst places to have a heart attack, so bad that it’s ominously nicknamed “the widowmaker.”

Now researchers at the Medical College of Wisconsin and in Germany have found that heredity may play an important role in widowmakers and other hazardous heart blockages.

Researchers say the finding is a big step in identifying genes for certain types of heart attacks and, eventually, it could lead to targeted therapies to prevent them.

“As we learn more and more and push this to the limit, we can get down to the point of personalized medicine,” said John Fakunding, director of the heart research program at the National Heart, Lung and Blood Institute, part of the National Institutes of Health, which funded the study.

For decades, doctors have known that heart disease runs in families. But the new research is believed to be the first large study showing that heredity can lead to coronary artery disease in specific locations. The study appeared Monday in Circulation: Journal of the American Heart Assn.

The scientists found a significant correlation between heart disease in the left main artery and the right coronary artery, the two main vessels supplying blood to the heart muscle. They also found that heredity was associated with abnormal widening of portions of heart vessels as well as the amount of calcium that builds up in coronary arteries.

The 10-year study involved analyzing angiograms of 882 siblings with coronary heart disease from 401 families in Germany. Researchers from the Medical College of Wisconsin and the University of Regensburg and the University of Luebeck, both in Germany, worked on the project.

While the study did not find specific genes related to the location or coronary artery disease, that is the ultimate goal, he said.

“I think we will find genes and family history will play a prominent role (in the location of blockages),” Broeckel said. “We want to quantify family history.”