PCSK9 inhibitors reduce low-density lipoprotein (LDL) cholesterol by up to 81% when used as an add-on to statin therapy in patients with hypercholesterolemia.

Study: Effects of AMG 145 on low-density lipoprotein cholesterol levels: results from 2 randomized, double-blind, placebo-controlled, ascending-dose phase 1 studies in healthy volunteers and hypercholesterolemic subjects on statins.

The study tested a PCSK9 inhibitor drug (AMG 145) in people with high cholesterol who were already taking statins, and found it lowered bad cholesterol by up to 81%, just like the claim says.

Study: PCSK9 inhibitors safely and effectively lower LDL after heart transplantation: a systematic review and meta-analysis

The study shows PCSK9 inhibitors lower LDL cholesterol in heart transplant patients, which supports the general idea, but it doesn't prove the exact 81% drop when added to statins in typical high-cholesterol patients.

Study: Ldl-cholesterol reduction with PCSK9 inhibitors: A meta-analysis of randomised controlled trials.

The study looks at drugs called PCSK9 inhibitors and finds they greatly lower bad cholesterol, especially when used with statins, which matches the claim.