Rhode Island researchers may have found clues about how cardiac arrhythmia (irregular heartbeat) triggers sudden cardiac death. In a new study, scientists worked with animals that had the two most common genetic forms of a condition that causes a rapid, irregular heartbeat in humans. Researchers found that both groups had problems with proteins that helped the heart muscle contract. But these faults were on different genes in each type of irregular heartbeat, and one of the gene's faults was more likely to lead to sudden death than the other. Scientists say their findings could lead to the development of new, genetically targeted therapies to treat and prevent fatal arrhythmia.