Alqahtani S, Nehme Z, Williams B, et al. - Via performing a retrospective cohort study of OHCAs in Victoria, Australia between 2000-2017, researchers sought to determine temporal changes in the incidence of OHCAs of presumed cardiac and non-cardiac aetiologies. They included 90,688 emergency medical service (EMS)-attended OHCAs occurring during the 18-year period. Of those, 64,422 (71.0%) and 26,266 (29.0%) were of presumed cardiac and non-cardiac etiology, respectively. Over the 18-year period, a 12.6% relative reduction in presumed cardiac events was observed and this was mainly due to a reduction in cases with an initial shockable rhythm and cases in patients aged 65-79 years. On the other hand, a 28.8% relative increase in non-cardiac events was evident over the 18-year period, and this was due to an elevation in initial pulseless electrical activity events and cases in patients aged ≥ 80 years. Following were the precipitating events with the largest 18-year raise in incidence: non-traumatic exsanguination, respiratory, and neurological. Per these findings, non-cardiac etiologies could be the leading cause of OHCA in the assessed region by 2052.