Because it occurs without warning, sudden cardiac death is a leading cause of death in the U.S. But now researchers say they’ve developed a model they can use to predict these nearly always fatal events.

Each year, more than 300,000 non-hospitalized Americans succumb to sudden cardiac death, the immediate and sudden stoppage of the heart.

Such deaths occur unexpectedly with little to no warning signs or symptoms and most commonly among people without a history of cardiovascular disease. Since these events occur in people who appear healthy and are not hospitalized, by the time help arrives, it is too late to save them.

Now, for the first time, researchers at the Perelman School of Medicine at the University of Pennsylvania in Philadelphia ay they’ve developed and validated a way to predict which people are at risk.

Researchers evaluated 17,884 adults, age 45 years and older with no history of cardiovascular disease, who were participants in two large studies sponsored by government’s National Institutes of Health.

They assessed the participants in a variety of ways, including demographics, clinical and laboratory data, cardiac electrocardiographic and echocardiographic measures, and biological markers.

The team identified 12 independent risk markers in their model that outperformed the current risk assessments for predicting sudden cardiac death. Of note, a low left ventricular ejection fraction, which has traditionally been the primary marker for identifying high risk individuals was present in only one percent and did not enhance risk prediction.

(A low ejection fraction is a score that tells how well the heart is pumping blood. If it falls too low, the heart can go into ventricular fibrillation, an irregular heartbeat that can stop it.)

The researchers hope their model, which is published in Circulation, can be used to help identify specific communities at higher risk and lead to increased awareness and training on the part of emergency personnel and the general public.