CAFÉ: Hypertension drugs have different effects on central aortic pressures

CAFÉ, a substudy of ASCOT, focused on 2,073 patients from the original ASCOT cohort who were followed for 5.5 years.

DALLAS – Results from a substudy of the Anglo-Scandinavian Cardiac Outcomes Trial suggest that nontraditional blood pressure measurements may more accurately reflect pressures elsewhere in the body than traditional brachial blood pressure measurements.

The Conduit Artery Function Evaluation (CAFÉ) study suggests that blood pressure measured in the arm may not accurately reflect circulation near the heart. That may also help explain why certain types of hypertension treatments have different effects on central aortic pressures and hemodynamics despite similar impacts on brachial blood pressures. Bryan Williams, MD, professor of medicine at the University of Leicester, presented the study in Dallas.

“Clinically relevant changes cannot be measured by brachial blood pressure,” Joseph Izzo, MD, of Millard Fillmore Hospital in Buffalo, said during a discussion period following the presentation at the American Heart Association Scientific Sessions 2005. “Drug action must be reconsidered because those drugs with favorable benefits on the arterial wall do better than others.”

Similarities and differences

The CAFÉ study focused on 2,073 patients from the original ASCOT cohort of 19,257. Patients were randomized to either amlodipine and perindopril (Aceon, Solvay) or to atenolol and a thiazide diuretic. In ASCOT, the amlodipine/perindopril arm was associated with a significant reduction in a composite outcome of cardiovascular events, including a 24% reduction in cardiovascular death.

After a mean follow-up of 5.5 years for patients in CAFÉ, researchers noted that brachial artery pressures were nearly identical between the two treatment groups.

However, central aortic systolic BP was significantly lower by 4.3 mm Hg in the amlodipine/perindopril group; central aortic pulse pressure was lower by 3 mm Hg.

The CAFÉ study also showed that increased central pulse pressure was a significant predictor of cardiovascular outcomes.

“The results of this study suggest that the difference in outcomes seen with amlodipine/perindopril may be the result of a difference in central aortic, rather than brachial, blood pressure,” Williams said.

Atrial pressure

CAFÉ patients were selected from five centers in the United Kingdom and were enrolled one year after being enrolled in the larger ASCOT study so that any uptitration or add-on therapy would be completed.

“Patients recruited into this study had reached their optimal dose level,” Williams said.

CAFÉ participants were similar to the overall ASCOT population. The mean age of the patients was 63 years, and all patients had a Framingham risk score of less than 20%.

In the CAFÉ study, researchers measured central aortic pressure by using the noninvasive Sphygmocor (ScanMed) system, which employs a computer program to estimate central aortic pressure by examining the shape of the pulse wave at the wrist. This information was then computed to generate a pulse wave and pressure measurements in the large arteries of the body. – by Jeremy Moore

For more information:

• Williams B. Differential impact of blood pressure-lowering drugs on central arterial pressure influences clinical outcomes: principal results of the Conduit Artery Function Evaluation (CAFÉ) study in ASCOT. Presented at the American Heart Association Scientific Sessions 2005. Nov. 13-16, 2005. Dallas.