2005 AHA Scientific Sessions: CAF? trial

Drugs that reduce brachial blood pressure similarly can have different effects on central blood pressure. This finding may explain differences in clinical end points between antihypertensive drugs that lower blood pressure similarly, said Bryan Williams, MD, lead investigator of the Conduit Artery Function Evaluation (CAFÉ) trial, a substudy of the Anglo-Scandinavian Cardiac Outcomes Trial (ASCOT).

"Brachial blood pressure is an imperfect surrogate for the effects of blood pressure-lowering drugs on central aortic pressures," Dr Williams said. "Moreover, central pressure appears to be an important determinant of clinical outcomes."

In CAFé, a subset of 2,199 patients who were recruited from ASCOT had their brachial blood pressure measured and had central aortic pressures derived by using a noninvasive computer program that examines the shape of the pulse wave at the wrist.

Although brachial pressures differed little between the treatment groups in CAFÉ, substantial reductions in trial-averaged values for central aortic pressures and hemodynamic values were observed in the amlodipine-perindopril group. Central aortic systolic blood pressure was 4.3 mmHg lower (P<.0001) and the central aortic pulse pressure was 3.0 mmHg lower (P<.0001) with the amlodipine-perindopril regimen compared with the beta blocker-thiazide diuretic regimen.

In CAFÉ, central pulse pressure was a significant determinant of total cardiovascular and renal end points using a Cox proportional hazards model (P<.05 when adjusted for baseline variables), said Dr Williams, professor of medicine, department of cardiovascular sciences, University of Leicester, UK.

"These findings provide a novel mechanism to explain the different clinical outcomes between the 2 blood pressure treatment arms in ASCOT and potentially other blood pressure-lowering treatment trials," Dr Williams said. The findings may also have significant implications for treatment guidelines, he added.