Researchers may have uncovered the reason why beta blockers are less effective at preventing stroke in older people with high blood pressure, when compared to other drugs for high blood pressure.
The findings of the CAFE (Conduit Artery Function Evaluation) and the ASCOT (Anglo-Scandinavian Cardiac Outcomes Trial) investigators, led by Bryan Williams, MD, professor of medicine at the University of Leicester in England, have been published in the Aug. 18 Journal of the American College of Cardiology.
Investigators recorded and analyzed central pressures derived from brachial pressure and radial pulse wave analysis in 2,073 patients, and 7,146 measurements were followed for up to four years.
They found that there was no impact of heart rate (HR) on brachial systolic or pulse pressures; however, there was a highly significant inverse relationship between HR and central aortic systolic and pulse pressures. Their results also showed that lowering HR in older people, as beta blockers do, can have a potentially detrimental effect on central aortic pressures.
Moreover, HR and brachial blood pressure accounted for 92 percent of the variability in central systolic and pulse pressures, the authors wrote. Consequently, drug-related differences in central aortic pressures were markedly attenuated after adjustment for HR.
“Such findings can help define the template for optimal treatment strategies and highlight why new methods to estimate central aortic pressures are providing new insights into the pathogenesis of cardiovascular disease and how new drugs can be tailored to limit the damage,” Williams said.
Williams, who also is consultant physician with the University Hospitals of Leicester NHS Trust, suggested that the present study provides insight into the mechanism. "There is no doubt that by better understanding of how modern drugs work in reducing the risk of stroke and heart disease, we will be able to continually refine treatments for the future," he said.
However, Williams stressed that patients should not stop taking their beta blockers. He emphasized that beta blockers are prescribed for a number of medical conditions, including angina and heart disease and in this context they are very beneficial.
"The new study is specifically exploring the reasons why beta blockers or other drugs that lower heart rate may be less effective at preventing stroke than some of the other drugs we use to lower blood pressure," Williams concluded.