schwit1 shares a report from The New York Times (Warning: source may be paywalled; alternative source): The patients were gravely ill, their hearts scarred by infections or heart attacks. In each, the electrical system that maintains a regular heartbeat had been short-circuited. They suffered frequent bursts of rapid heartbeats, which can end in sudden death. The condition kills an estimated 325,000 Americans each year, the most common cause of death in this country. And these people had exhausted all conventional treatments. So researchers at Washington University in St. Louis offered the patients something experimental: short bursts of radiation aimed at their hearts in an effort to obliterate the cells that were causing the electrical malfunctions. Results in the first five patients were published on Thursday in the New England Journal of Medicine, and the experiment seems to have worked -- offering hope to similar patients everywhere who have had no alternatives except a heart transplant. The treatment requires weeks to take full effect, so it cannot be used for cardiac patients who need immediate help. And the method must be studied in larger groups of patients over longer times, an effort that has already begun.