Effect of known history of heart disease on survival outcomes after out-of-hospital cardiac arrests

Objective: We aimed to investigate the effect of known heart disease on post-out-of-hospital cardiac arrest (OHCA) survival outcomes, and its association with factors influencing survival. Methods: This was an observational, retrospective study involving an OHCA database from seven Asian countries in 2009-2012. Heart disease was defined as a documented diagnosis of coronary artery disease or congenital heart disease. Patients with non-traumatic arrests for whom resuscitation was attempted and with known medical histories were included. Differences in demographics, arrest characteristics and survival between patients with and without known heart disease were analysed. Multivariate logistic regression was performed to identify factors influencing survival to discharge. Results: Of 19 044 eligible patients, 5687 had known heart disease. They were older (77 vs 72 years) and had more comorbidities like diabetes (40.9 vs 21.8%), hypertension (60.6 vs 36.0%) and previous stroke (15.2 vs 10.1%). However, they were not more likely to receive bystander cardiopulmonary resuscitation (P = 0.205) or automated external defibrillation (P = 0.980). On univariate analysis, known heart disease was associated with increased survival (unadjusted odds ratio 1.16, 95% confidence interval 1.03-1.30). However, on multivariate analysis, heart disease predicted poorer survival (adjusted odds ratio 0.76, 95% confidence interval 0.58-1.00). Other factors influencing survival corresponded with previous reports. Conclusions: Known heart disease independently predicted poorer postOHCA survival. This study may provide information to guide future prospective studies specifically looking at family education for patients with heart disease and the effect on OHCA outcomes.