The doubtful association between blood lipid changes and progression
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International Journal of Cardiology Letter to the Editor The doubtful association between blood lipid changesand progression Uffe Ravnskov Magle StoraKyrkogata 9, 22350 Lund, Sweden |
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Article history: Received 20 August 2011 Recently Tenenbaum et al. reported that long-term changes in serum cholesterol did not correlate with the progression of coronary calcium measured by computerized tomography (1). Their finding shows that the benefit of various cholesterol-lowering treatments obtained in many angiographic trials must be caused by other and unknown factors. The authors argued that one of the reasons to the lack of exposure/response may be that calcific plaques are resistant to undergoing changes in size in response to systemic anti-atherosclerotict herapy. However, other studies using different techniques and other kinds of outcome have also shown lack of exposure/response. In a previous review of the angiographic cholesterol-lowering trials I identified sixteen trials in which the authors had calculated exposure/response between changes in low-density and/or total cholesterol, and degree of athero-sclerotic progress measured either as change of minimum lumen diameter or percent stenosis (2). In these trials almost all kinds of cholesterol lowering were used, including LDL-apheresis, multiple riskfactor reduction, low-fat diet and exercise, as well as drug treatment with cholestyramine, colestipol, niacin, fenofibrate, probucol, bezafibrate, lovastatin, pravastatin and simvastatin. With one exception no exposure/response was recorded in any of these trials. The exception was a trial where the only treatment used was physical exercise. In 12 of the trials exposure/response was also calculated for HDL-cholesterol, in ten for tri-glycerides, in six for |
apolipoprotein B, in three for apolipoprotein A1, in three for VLDL-cholesterol and in one for small, dense LDL-cholesterol; in all of them the result was the same: no exposure-response. The findings of Tenenbaum et al. are in agreement with the previous study by Hecht and Harman (3), who found no association between the degree of LDL-cholesterol lowering and calcified plaque progression, using electron beam tomography. Exposure-response has also been absent (4-6) and even inverse (7) in observational angiographic studies. Obviously the benefit achieved by the various cholesterol-lowering treatments is caused by factors other than lowering of the blood lipids. Presence of exposure/response is not necessarily proof of causality, but its absence definitely disproves it. Therefore, the findings of Tenenbaum et al. cast doubt on the current view about the causation of atherosclerosis by plasma lipoproteins.References [1] Tenenbaum A, Shemesh J, Koren-Morag, Fisman EZ, Adler Y, Goldenberg I, et al. Long-term changes in serum cholesterol level does not influence the progression of coronary calcification. Int J Cardiol 2011;150:130-4. |
| Please cite this article as: Ravnskov U, The doubtful association between blood lipid changes and progression of atherosclerosis, Int J Cardiol (2011), doi:10.1016/j.ijcard.2011.08. |
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