G. Walldius et al., THE EFFECT OF PROBUCOL ON FEMORAL ATHEROSCLEROSIS - THE PROBUCOL QUANTITATIVE REGRESSION SWEDISH TRIAL (PQRST), The American journal of cardiology, 74(9), 1994, pp. 875-883
The Probucol Quantitative Regression Swedish Trial tested whether trea
tment of hypercholesterolemic persons with probucol for 3 years affect
ed femoral atherosclerosis. The primary end point was the change in at
heroma volume estimated as change in lumen volume of the femoral arter
y assessed by quantitative arteriography. Three hundred three patients
with visible atherosclerosis were randomized to probucol 0.5 g twice
daily, or to placebo. All patients were given diet and cholestyramine,
8 to 16 g/day. Twenty-nine patients were excluded because of inadequa
te primary end point measurements. The mean age of the remaining 274 s
ubjects (158 were men) was 55 years. Seventeen percent had intermitten
t claudication and 24% bad angina pectoris. After 3 years, the probuco
l-treated patients had 17% lower serum cholesterol, 12% lower low-dens
ity lipoprotein cholesterol, 24% lower total high-density lipoprotein
cholesterol, and 34% tower high-density lipoprotein(2) cholesterol lev
els than control subjects. All lipoprotein differences between the tre
atment groups remained highly significant during the trial. There was
no statistically significant change in lumen volume between the probuc
ol and the control group. Furthermore, there was no difference between
the treatment groups with regard to change in arterial edge roughness
or amount of aorto-femoral atherosclerosis; neither were there any di
fferences between the treatment groups with regard to change in ST-seg
ment depressions on exercise tests or ankle/arm blood pressure (second
ary end points). In the control group, lumen volume increased (p <0.00
1) and roughness of the femoral artery decreased (p <0.05). It is conc
luded that the addition of probucol to diet and cholestyramine did not
result in any significant regression of atherosclerosis compared with
that found in patients treated only with diet and cholestyramine. How
ever, in this control group there was statistically significant eviden
ce of improvement.