SYDNEY - More Australians are implanting in their bodies life-saving devices that prevent cardiac death, but it is unclear whether the trend reflects an increasing need for the implants or a heightened awareness of risk factors for the heart-linked sudden deaths, according to latest Australian research.

The implantable cardioverter defibrillators (ICD), which work by delivering an electric shock to the heart to restore its function, are being surgically inserted in patients at increasing rates and at a cost of almost 155 million Australian dollars (114.7 million U.S. dollars) a year, with the number of related medical procedures up from 1,844 in 20022003 to 6,504 in 20142015, the Medical Journal of Australia said in a statement explaining the study late Sunday.

It is unclear whether the overall increase in procedure rates reflected an increasing need for ICD therapy, or was a direct result of increased awareness of risk factors for sudden death, the researchers, led by Dr. Jodie Ingles from the Centenary Institute medical research facility, wrote in their report that was published in the journal.

The study, the first of its kind in Australia, analyzed data from a national hospital morbidity database to determine the number of ICD procedures by year, patient age and sex, and to estimate age group-specific population rates and associated costs, according to the journal.

A cardiac arrest or sudden cardiac death occurs when the heart suddenly stops beating, often triggered by an electrical malfunction in the organ that causes its muscle to beat ineffectively, according to the Heart Foundation charity.

The researchers said a patient-centered approach to care, including discussing the benefits and risks of ICD therapy with the patient and their family, is essential".

The proportion of women among patients undergoing ICD procedures was also relatively small at about 20 percent and the possibility that ICD therapy was being underused in female patients should be investigated, they said.

The high removal rate of the devices was also notable and should be a a priority for investigation with the most frequent reasons cited being post-surgical infection, device malfunction, misdiagnosis of a heart condition, or lack of clinical benefit, said the researchers.