We tested the hypothesis that, compared with placebo, simvastatin would reduce the progression of coronary artery calcium (CAC) and abdominal aortic calcium (AAC) levels in participants asymptomatic for vascular disease. Total CAC and AAC were measured with multidetector cardiac computed tomography. Inclusion criteria were a CAC score of >or=50 Agatston units, high-density lipoprotein (HDL) cholesterol level<or=50 mg/dl, low-density lipoprotein (LDL) cholesterol level between 100 and 160 mg/dl, and >or=2 other risk factors. Diabetes and history of vascular disease were exclusion criteria. Participants were randomized to receive 80 mg simvastatin (n=40) or matching placebo (n=40) for 12 months. Lipids were measured at 3-month intervals, and CAC and AAC measurements were repeated at 6 and 12 months. Total cholesterol, triglycerides, and LDL decreased significantly with simvastatin treatment (p<0.0001 for all comparisons, adjusted for baseline levels), whereas lipids remained unchanged for subjects randomized to receive placebo. Total CAC volume increased from baseline in both treatment groups. For subjects in the active treatment group, CAC volume increased by 9%, whereas in the placebo group, plaque volume increased by 5% (p=0.12 for treatment effect). AAC volume also increased in both treatment groups (p=0.15 for treatment effect). In conclusion, simvastatin treatment does not reduce progression of CAC or AAC compared with placebo.
"In fact, in patients treated with atorvastatin vs. placebo with a median follow up of 24 months, the rate of change in coronary artery calcification was 26%/year vs. 18%/year, respectively, with a geometric mean difference of 7%/year (95% CI À3 to 18%, P ¼ 0.18), and did not correlate with serum LDL concentrations (r ¼ 0.05, P ¼ 0.62) . Likewise, in subjects receiving simvastatin vs. placebo, total CAC volume increased from baseline in both treatment groups (9% vs. 5%; P ¼ 0.12 for treatment effect), as did abdominal aortic calcium (P ¼ 0.15 for treatment effect) . A lower calcium index at IVUS was also associated with a higher rate of patients showing substantial change in atheroma burden in response to established medical therapies than a higher one (at least 5% change in atheroma volume, 70% vs. 53%, P < 0.001) . "
[Show abstract][Hide abstract] ABSTRACT: Currently used methods of computerized tomographic image reconstruction require a large number of measurements relative to the number of picture elements to be estimated, but employ computationally simple algorithms. However these reconstruction methods do not optimally use the information contained in the measurements. Using a stochastic analysis, the inherent statistical assumptions of some seemingly deterministic reconstruction techniques are examined, and a class of recursive algorithms are developed which use data more efficiently at the price of a small increase in computational complexity per measurement. These algorithms will be useful in cases where the number of measurements are limited by time, cost, geometry, or independence constraints. Examples of reconstructions using state-estimation methods such as square-root, Chandrasekhar, and related algorithms will be discussed.
Decision and Control including the 16th Symposium on Adaptive Processes and A Special Symposium on Fuzzy Set Theory and Applications, 1977 IEEE Conference on; 01/1978
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