Out of hospital cardiac arrest in STEMI patients: A six-year review of an Irish tertiary referral centre

Background and objectives: Out of hospital cardiac arrest (OHCA) can complicate ST segment elevation myocardial infarction (STEMI), with a tenfold increase in mortality compared to those presenting without cardiac arrest. This study aimed to characterise STEMI patients presenting with OHCA to a single centre and to investigate the factors affecting their outcomes. Methods: A retrospective analysis was performed on all patients on the National Out of Hospital Cardiac Arrest Register that presented over a six-year period with OHCA. The hospital's electronic health record was used to collect data on baseline characteristics, STEMI diagnosis, treatment and outcomes. Results: There were 478 OHCA presentations; 75 (16 %) were diagnosed with STEMI. Mortality rates were significantly lower amongst the STEMI patients (23 % vs 87 %). There was no significant difference in the characteristics of STEMI patients transferred directly to the coronary catheterisation lab (CCL) and initially treated in ED. Over 90 % of STEMI patients were successfully treated with PCI. Mortality was higher in STEMI patients that were initially transferred to ED, with this factor identified as an independent predictor of mortality. However, transfer to CCL after two hours was not associated with increased mortality, when compared to those transferred within an hour of hospital arrival. Conclusion: Mortality rates amongst studied STEMI patients presenting with OHCA were high. Although transfer to ED was associated with increased mortality, this finding may be explained by confounding factors, including more profound haemodynamic instability precluding STEMI diagnosis, and/or requiring transfer to ED for stabilisation.