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) a year, reports Xinhua news agency.

The number of related medical procedures is gone up from 1,844 in 2002-03 to 6,504 in 2014-15, the Medical Journal of Australia said in a statement explaining the study late on July 29. 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 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.