Hospitals around the country have been spending millions of dollars to buy automated defibrillators to save the lives of more patients who go into sudden cardiac arrest. The purchases were spurred by a 2000 recommendation from an American Heart Assn. committee that said the equipment would bring patients speedier emergency medical help. But today the costly investment increasingly seems to have been a mistake. Research suggests that the new gear, now found in nearly all hospitals, saves fewer lives than the old, lower-tech defibrillators. By one estimate, the switch to automated defibrillators means that close to 1,000 more hospital patients die of cardiac arrest every year in the U.S.