Lower BP in CAD Heralded by CAMELOT
November 9, 2004 (eshonline.org) - In patients with coronary artery disease (CAD) and a baseline blood pressure of only 129/78 mm Hg, a 31% relative reduction in cardiovascular events (CVE) was produced by a 5/3 mm Hg reduction in blood pressure with amlodipine compared to placebo in the CAMELOT trial. The absolute reduction was 6.5% in CVE. Enalapril compared to placebo reduced blood pressures by 5/2 mm Hg and produced a non-significant 15.3% relative reduction in CVE and a 2.9% absolute reduction. The CVE rates were 23.1% with placebo, 16.6% with amlodipine, and 20.2% with enalapril. The number needed to treat was 16 with amlodipine to prevent 1 CVE.
The double-blind, multicenter Comparison of Amlodipine vs Enalapril to Limit Occurrence of Thrombosis (CAMELOT) trial randomized 1,991 patients with CAD and normal blood pressure to placebo, amlodipine (10 mg) or enalapril (20 mg) for 24-months. The primary end point was the time to first occurrence of an adverse CVE (CV death, nonfatal heart attack, coronary revascularization, hospitalization for angina pectoris, hospitalization for CHF, fatal or nonfatal stroke, or diagnosis of vascular disease).
Notably, amlodipine slowed the progression of coronary artery atherosclerosis a subset of 274 patients who underwent IVUS examinations.
Published in the November 10 issue of JAMA (2004 ;292:2217 -2226), the authors of CAMELOT state that these results mean that the optimal blood pressure range for patients with CAD may be substantially lower than indicated by current guidelines. The optimal use of antihypertensive agents in patients with CAD has been uncertain despite 30 years of clinical trials. In an accompanying editorial, Dr. Carl Pepine, University of Florida College of Medicine, Gainesville , stated that the findings in CAMELOT raise the question of what is the optimal target blood pressure in CAD to reduce the progression of atherosclerosis. These data suggest "that the optimal level is clearly lower than 140 mm Hg systolic and perhaps in the 120 mm Hg range."
The CAMELOT Study
Editorial Comment
Prof. A.M. Heagerty
Editor-in-Chief - Esh Website
It has become highly topical to examine the management of hypertension in categories of patients with particular forms of target organ damage. In this context and because of the concerns about treating patients with pre-existing coronary artery disease, a number of trials have been established to try and investigate whether one particular class of agent is superior to others in terms of outcomes. The CAMELOT trial has now been published but is a study with a difference. Here individuals with coronary artery disease but normal blood pressure have been recruited. This notwithstanding good falls in both systolic and diastolic blood pressure were achieved in the two active drugs examined, namely, Amlodipine and Enalapril. Placebo was neutral. After 24 months of follow-up there was a significant reduction in cardiovascular events in subjects that received Amlodipine b+ut not Enalapril although this maybe as a result of a short time of follow-up or the power of the study as originally conceived. What was also interesting was that intravascular ultrasound suggested that there was a slowing down of atheroma progression in the coronary vessel providing a mechanism by which the anti-hypertensive drugs had actually achieved a reduction in cardiac events.
This is not the first study to demonstrate that calcium channel blockers with established coronary artery disease and relatively normal blood pressure can be beneficial. Indeed in this area ACE inhibitors have also been found to be useful in other investigations such as the HOPE trial.
Once again a clear cut message emerges. Buried within the paper is clear evidence that a substantial number of patients that were randomised into this trial had a previous history of hypertension. Their normal blood pressure at the time of recruitment might well represent either myocardial damage as a result of previous cardiac events or the use of other anti-hypertensive drugs. To a certain extent this should not deter us from taking home a clear cut message, which is that in patients with established coronary artery disease, blood pressure should be as rigorously controlled as possible and that that blood pressure control should be combined with normalisation of cholesterol and the administration of aspirin or an anti-platelet drug unless contraindicated. |
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