In this review, we focus on the currently available evidence on platelet hyperreactivity in PH and the effects of PCSK9 inhibitors on platelets, including: (i) the pathophysiology of atherosclerosis in PH, (ii) the mechanisms underlying platelet hyperreactivity in PH, and (iii) the anti-atherogenic and antiplatelet effects of PCSK9 inhibitors. The gene discussed is PCSK9; the disease is atherosclerosis.