It is widely believed that atherosclerosis, the 'furring up' of the
arteries, narrows the coronary arteries and makes a heart attack more likely in
two ways: Firstly, a clot in a partially blocked artery is more likely to block
it completely, cutting off the blood supply downstream; and secondly, the
atherosclerosis itself may block the artery with a similar result.
Many
laymen have been led to believe that cholesterol is to blame for the blockage,
or 'plaque', but this is hotly disputed. Much more likely, it seems, is that
calcification of the artery wall, which hardens the artery wall making it less
pliable, is the cause.
Statin Use Tied to Faster Plaque
Buildup
A small observational American study of war veterans
with diabetes and advanced coronary heart disease has found that those who
regularly took statins had accelerated progression of calcification. This
current analysis included 197 participants with type 2 diabetes from the Risk
Factors, Atherosclerosis, and Clinical Events in Diabetes (RACED) study, a
substudy of the Veterans Affairs Diabetes Trial (VADT) study.
Study
participants who were frequent statin users were found to have significantly
more coronary plaque advancement than those who were less frequent users
(
P<0.001), according to Aramesh Saremi, MD, and colleagues from the
Phoenix VA Health Care System in Arizona.
The results remained the same
even after adjusting for age, duration of diabetes, hypertension, cardiovascular
events, baseline coronary artery calcium, race and ethnicity, blood pressure,
total cholesterol/high density lipoprotein cholesterol (HDL-C), and body mass
index, Saremi's team reported here at the annual meeting of the American
Diabetes Association.
But Cam Patterson, MD, from the Center for Heart
and Vascular Care at the University of North Carolina at Chapel Hill, and who
was not involved in this study, warned that it would be a 'horrible mistake to
infer that strict compliance with statin use is somehow causally associated with
progression of atherosclerosis
. Adding that he thought that such a
conclusion is definitively a false one.
'The patients who were more
compliant with statin therapy had much higher calcium scores at baseline, so
these are obviously patients who had a substantially greater propensity for
atherosclerosis to begin with,' Patterson said
. He suggested that
patients who already have vascular disease are more likely to be compliant with
their statins.
Saremi does not disagree with Patterson; the progression
of calcification may be linked to the healing of soft plaque initiated by statin
therapy.
'It's important now to determine whether this progression of
calcification leads to cardiovascular events.
She also suggested that if
diabetics are put on statins earlier in the course of their disease, when their
calcium scores are low, there may not be such a rapid advancement of
calcification. But this is unsupported supposition.
In this
substudy, 36 patients reported less frequent statin use, while 161 reported more
frequent use. The mean age of patients was 61 and the average follow-up was 4.6
years.
In the unadjusted model, researchers found that every 10% increase in
statin use was associated with a 0.41 mm
3 increase in coronary
calcium progression (
P<0.01), which did not change much in the
adjusted model: 0.33 mm
3 increase (
P=0.04).
When
researchers excluded those with prior or new cardiovascular events, the risk for
calcium progression remained the same.
Saremi and colleagues speculated
that statins may enhance the density of calcification as part of the healing
process, potentially contributing to plaque stabilization and decreased
cardiovascular disease events . But this is more unsupported speculation (they
don't like to give up on statins, even though statins have also been shown to
increase diabetes risk). However, they did also suggest that the advancement of
plaque in type 2 diabetics who frequently took statins may lessen the
medication's overall benefit.
Reference:
Saremi A, et al. Progression of vascular calcification
is increased with statin use in the Veterans Affairs Diabetes Trial (VADT)"
ADA 2012; Abstract 426-P.
===============================================================================================================
Read the complete article here.