An experimental drug has shown promise for high-cholesterol patients who are not able to manage their condition with diet, exercise and current drugs.

People taking an experimental drug called Repatha (evolocumab) for high cholesterol were half as likely to die or suffer a heart attack or stroke as those taking conventional statins, researchers said.

The findings were based on 4,465 patients who were studied for one year after completing an earlier phase of the drug's safety and efficacy testing.

The results could offer an alternative to patients with high low-density lipoprotein (LDL) cholesterol who are unable to manage their condition with diet, exercise and statin drugs currently on the market.

Patients were randomised to either receive evolocumab, made by the pharmaceutical company Amgen, injected under the skin in addition to standard care, or standard care alone, which meant taking the cholesterol-lowering statin drug recommended by their physician.

Evolocumab works differently than traditional statins. It is a human monoclonal antibody that blocks a harmful protein in the liver, freeing the organ up to remove LDL cholesterol from the blood.

This new class of drug is known as a PCSK9 inhibitor, and three different kinds, including evolocumab, are being studied in large clinical trials.

The drug has yet to be approved by the US FDA, and more years of study are planned to test its longer term outcomes.

But after one year, analysis showed the rate of cardiovascular events - such as death, heart attack or stroke - in the evolocumab group was 0.95 per cent, compared to 2.18 per cent in the traditional statin group.

The results were presented at the American College of Cardiology annual conference in San Diego, California, and published in the New England Journal of Medicine.