Associate Professor Ian Scott, Director of Internal Medicine at Princess Alexandra Hospital in Brisbane, and his colleagues, say the most common reasons patients did not receive treatment included older age and a previous history of ACS.
Approximately 100,000 Australians are hospitalised each year with ACS.
Assoc Prof Scott says six out of eight therapies were used less frequently in high-risk than in low-risk patients.
"Patients at highest absolute risk of death or recurrent coronary events would be expected to derive greater benefit from treatment than lower-risk patients," says Assoc Prof Scott.
The study suggests treatment may be withheld for a number of reasons, including concerns over treatment related risk to the patient, underestimation of treatment benefits, cost-effectiveness, and lack of access to therapies.
Assoc Prof Scott's article says further research is needed to know which treatment omissions are responsible for the majority of poor outcomes.
In addition, he recommends professional education programs, tools to help physicians calculate individual patient risk, more specific guideline recommendations, and better networking between hospitals to equalise access to all available therapies.
The Medical Journal of Australia is a publication of the Australian Medical Association.