Death rates and heart failure in hospitalized heart attack patients have fallen sharply in the last six years, most likely because of better treatment, the largest international study of its kind suggests. The promising trend parallels the growing use of cholesterol-lowering drugs, powerful blood thinners and angioplasty, the researchers said. The six-year study involved nearly 45,000 patients in 14 countries who had major heart attacks or dangerous partial artery blockages. The percentage of patients who died in the hospital or who developed heart failure was cut almost in half from 1999 to 2005.