With all the buzz about the ability of statins to prevent
myocardial infarction (MI) and coronary death by decreasing
atherosclerotic progression, you might assume that the
link between coronary atherosclerotic progression and
cardiovascular event risk has been well documented. Strangely
enough it hasn't — until now.
Dr Wendy Mack, associate professor
in the Department of Preventive Medicine at the University
of Southern California and the other members of the
Monitored Atherosclerosis Regression Study (MARS) used
quantitative coronary angiography to determine whether
atherosclerotic progression is, in fact, associated
with an increased risk of subsequent cardiovascular
events. And they found the missing link.
"The major messages of our study
are twofold. First, these data from the MARS trial provide
further evidence that clinical trials that use atherosclerosis
imaging measures, specifically quantitative coronary
angiography, provide valid surrogate endpoints for cardiovascular
morbidity and mortality outcomes. Second, our study
supports the long-term cardiovascular benefits of lipid-lowering
therapy as an atherosclerosis-reducing intervention,"
says Dr Mack.
MESSAGE
FROM MARS
The MARS trial showed that as plaques grew in arteries,
reducing the luminal diameter and blocking flow, the
chance of a cardiovascular event increased. Even more
noteworthy, in cases where luminal diameter actually
increased, meaning the plaque shrank, the chance of
an event decreased.
This latest report, appearing in
the June issue of the American Journal of Cardiology,
presents data from 173 participants enrolled in the
study. These patients were under the age of 70 and had
coronary artery disease evident on angiography, with
one non-occluded segment showing at least 50% stenosis.
During the two-year lovostatin
(40mg or placebo twice daily) treatment phase of MARS,
the team looked at the change in percent stenosis in
coronary arteries with atherosclerotic plaques. They
also examined the change in lumen diameter in these
same lesions along with other measures of plaque progression.
The observational phase of the trial then began, with
patients being contacted annually for an average of
9.4 years. Incidence of coronary death and MI was the
primary endpoint, but researchers also recorded other
cardiovascular conditions and surgeries.
Data analysis revealed that increase
in percent stenosis was associated with a 55% increase
in risk of coronary death or MI, and a 47% increase
in any cardiovascular event. On the other hand, an increase
in lumen diameter was associated with a 21% decrease
in risk of the primary endpoint, and a 19% decrease
in risk of any event.
Am J Cardiol Jun 2005;95(11):1277-82
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