Is there no connection between total or ldl cholesterol levels and extent of atherosclerosis?

Yes : There is not a direct correlation but in general the higher your cholesterol, the higher your risk of developing atherosclerosis.

The best correlation: The best correlation is between fasting ldl/hdl ratio, followed by chol/hdl ratio. Your cholsterol measurement alone is much less important!

Depends on Particles: Atherosclerosis is related to the number of LDL particles (LDL-P) and HDL particles (HDL-P). High LDL-P and low HDL-P are both related to atherosclerosis. Because cholesterol in LDL and HDL particles is highly variable cholesterol levels often disagree with particle number. When LDL-C and LDL-P agree each predicts risk equally well. When they disagree CVD risk tracks with LDl-P, but not LDL-C.