People with high cholesterol are refusing to take prescribed heart medicine, a new study has found, prompting calls for better cardiovascular health awareness.

The study, which reviewed the medical data of millions of US citizens, found one in five people at high risk of heart disease are not taking statin therapy.

Statins work by lowering the amount of cholesterol in the blood, preventing the fat from accumulating and blocking a person's coronary arteries.

The study also found women were more likely to refuse statins when prescribed them than men, resulting in poorer health outcomes.

The findings have serious implications for the 6.5 million Australians - including 3.6 million women - who live with high cholesterol, Heart Foundation Healthcare programs manager Natalie Raffoul says.

"Cardiovascular disease is a leading cause of death among Australian women second only to dementia," she said.

"Statin therapy is the gold-standard, first-line, cholesterol-lowering medication prescribed for high-risk individuals to help reduce their chances of having a heart attack or stroke.

"If you are prescribed statins by your GP ... it's crucial that you consider taking these medicines, which are commonly regarded as having been critical to the reduction in cardiovascular death in Australia over the last 50 years."

Heart disease remains the leading cause of death in Australia, responsible for more than one in four lives lost.

Recent research confirmed fears COVID-19 exacerbated poor heart health, because lockdowns deprived Australians of opportunities to exercise.

The study by the Victor Chang Cardiac Research Institute found cholesterol, blood sugar and blood pressure levels were all significantly higher than before the pandemic.

Ms Raffoul said more work was needed to understand why patients were reluctant to take statins and what can be done to improve its uptake.