DALLAS (CNN/Money) - Pfizer's high blood pressure treatment Norvasc does a better job of decreasing the risk of fatal heart attacks than generic blood pressure drugs known as beta blockers, according to data released Sunday at the American Heart Association conference.

Patients with high blood pressure taking Norvasc experience a 16-percent reduction in cardiovascular events including death, compared to patients who took the generic beta blocker atenolol, said Dr. Bryan Williams, an independent research director for the Pfizer-funded "CAFE" study.

"The assumption has been that all types of blood pressure treatments are equally effective," said Williams, professor of medicine in the cardiovascular department at the University of Leicester in the United Kingdom. "We show that this assumption is untrue."

Norvasc sales totaled $4.5 billion in 2004 and is one of Pfizer's top-selling products. Pfizer (Research), based in New York City, is the world's biggest drug maker, with more than $50 billion in 2004 sales.

The benefit of Norvasc over the older beta blockers was discovered by measuring aortic blood pressure, or blood pressure near the heart, through the measurement of pulse waves in large arteries. Measuring blood pressure in the arm, the more traditional method, underestimated the benefit of Norvasc, according to the study.