Patients with high blood pressure taking a mixture of newer drugs may cut their risk of stroke by 25 percent and dangerous heart complications by 15 percent compared with those on older pills, according to a large study released on Tuesday.The advantage is so dramatic that many patients on the older regime of a beta blocker drug and a diuretic should halt their treatment and begin taking the newer combination, which includes Pfizer Inc.'s .drug Norvasc and CV Therapeutics’ Aceon, researchers said.The 20,000-person, Pfizer-funded study was halted early, last November, after researchers found the drugs were so much better than conventional treatment with a beta-blocker and a diuretic. Full results were presented at the American College of Cardiology meeting in Orlando, Florida, which ends on March 9.The newer drugs are Norvasc, known generically as amlodipine, a calcium channel blocker and perindopril, an ACE inhibitor, sold by CV Therapeutics and Solvay Pharmaceuticals as Aceon.They were tested in the study against AstraZeneca’s atenolol, a beta blocker that has been off patent for several years, and a diuretic pill.