Here's the part of the National Cholesterol Guidelines that covers this. I will post the complete link at the end of this post this quote is on page II-21 article 3. It's 284 pages long!!
Serum Lp(a) is relatively resistant to therapeutic lowering.
Statin drugs are ineffective. Among currently available
drugs, only nicotinic acid reduces Lp(a) concentrations,
and only moderately.283,284 In postmenopausal
women, estrogen therapy also causes some reduction
in Lp(a) concentrations.285 Although these therapies
typically lower elevated Lp(a) levels, they have not
been widely adopted. At present no clinical trial
evidence supports a benefit from lowering Lp(a) levels
with particular agents.
http://www.nhlbi.nih.gov/guidelines/cholesterol/atp3full.pdf