Etiology of Out-of-Hospital Cardiac Arrest Among Patients Presenting to the Emergency Department of a Tertiary Care Hospital in Bhutan: A Prospective Cohort Study.
Emergency medicine international · 2026-01-01 · Observational study
Abstract
BACKGROUND: High mortality rates following out-of-hospital cardiac arrest (OHCA) make identification of its etiology vital for prevention. In low-resource settings, limited access to diagnostics and clinical autopsy often prevents definitive conclusions. This study aimed to describe the presumed etiology of OHCA cases presenting to a tertiary emergency department (ED) in Bhutan. METHODS: A prospective cohort study was conducted from August 1, 2023, to July 31, 2024, in the ED of the National Referral Hospital, Bhutan. All patients presenting with OHCA were included and followed until hospital discharge, death, or the end of the study period. Data were extracted from patient records and analyzed using STATA Version 18. RESULTS: Of the 110 OHCA patients, 59.1% (n = 65) were male, and 90.9% (n = 100) were adults, with a median age of 53 years (IQR: 32-69). Prehospital emergency medical services (EMS) attended 27.3% (n = 30) of cases, and resuscitation was attempted in the ED in 93.6% (n = 103). Using the 2024 Utstein OHCA framework, medical causes accounted for 91.8% (n = 101) of presumed etiologies and trauma for 6.4% (n = 7). Within medical causes, presumed cardiac/unknown was most common (68.3%, n = 69), followed by other medical (26.7%, n = 27) and respiratory causes (5.0%, n = 5). One case each was attributed to drowning/electrocution and asphyxiation (0.9%). Among the 69 presumed cardiac/unknown causes, 94.2% (n = 65) had no specific etiology identified after available evaluation, while 5.8% (n = 4) had clinical features suggestive of a cardiac etiology. No clinical autopsies were performed. In multivariable logistic regression, increasing age was independently associated with presumed cardiac/unknown with no specific etiology identified after available evaluation (aOR: 1:02; 95% CI: 1.00-1.03; p = 0.022), and no other variables were significantly associated with this outcome. CONCLUSION: Most OHCA cases were medical in origin, with the majority classified as presumed cardiac/unknown due to the absence of a specific etiology after available evaluation. These findings highlight challenges in etiological classification in resource-limited settings. Strengthening postresuscitation diagnostic evaluation, standardized post-ROSC protocols, access to clinical autopsy where feasible, and development of a nationwide OHCA registry may improve etiological classification and guide future preventive strategies.