PCSK9 and myocardial infarction: However, levels of LPA (apolipoprotein[a]), the characteristic protein component of lipoprotein(a), remained unchanged in PCSK9 mAb-treated patients with MI, since a rise of LPA was observed in the placebo group post-MI.<h4>Conclusions</h4>Most apolipoprotein changes after PCSK9 mAb therapy following MI were mediated by low-density lipoprotein cholesterol lowering.