You won't find a lot of scientific validation for this, but it is my firm impression that small LDL, by some crazy means, has the capacity to "turn on" or "turn off" lipoprotein(a), Lp(a).
Recall that Lp(a) is a specific genetic trait, passed to us (if you have it) by mother or father. It falsely elevates LDL cholesterol and escalates heart disease risk more than just about any other known abnormality.
A frequent hint that Lp(a) might be present is a comment I hear often from patients: "My doctor said statin cholesterol drugs don't work for me. I tried them all and my cholesterol won't go down." Or, the result was substantially less than expected. That's because, when Lp(a) is lurking in your cholesterol value, it is unaffected by the statins.
It's been my in-the-trenches observation that, the more fully expressed the small LDL pattern becomes, the worse the Lp(a) behaves. In other words, if small LDL is suppressed effectively, Lp(a) doesn't seem to carry the same dangers as in someone who has plenty of small LDL. I don't know why this is. (I expect that the answer will come from someone like Dr. Marcovina at Stanford, who is at the forefront of Lp(a) structural research. Lp(a) is a complex molecule with several components. How and why it interacts with other particles remains a mystery.)
There are a little bit of data to confirm this. The Quebec Cardiovascular Study has presented some data to this effect, that the combination of small LDL particles and Lp(a) are a particularly lethal combination. We are trying to correlate our data from a CT heart score perspective to discern any statistical relationships.
This raises a very important therapeutic issue if you have Lp(a): the worst thing you can do if you have Lp(a) is become overweight. Excess abdominal fat is a huge trigger to create small LDL particles. Even though being overweight itself has no effect on the measured level of Lp(a), it activates small LDL which, in turn, throws gasoline on the Lp(a) fire.