Heart Rate After Resuscitation From Out-of-Hospital Cardiac Arrest due to Acute Coronary Syndrome Is an Independent Predictor of Clinical Outcome

Background: Heart rate (HR) is a useful predictor of cardiovascular disease, especially in acute coronary syndrome (ACS). However, it is unclear whether there is an association between HR and clinical outcomes after resuscitation from out-of-hospital cardiac arrest (OHCA) due to ACS. The aim of this study was to investigate the impact of HR on clinical outcome in individuals resuscitated from OHCA due to ACS. Methods and Results: Data from 3,687 OHCA patients between October 2002 and October 2014 were retrospectively analyzed. We divided 154 patients diagnosed with ACS into 2 groups: those with tachycardia (HR >100 beats/min, n=71) and those without tachycardia (HR 100 beats/min, n=83) after resuscitation. The primary endpoint was 1-year mortality and the secondary endpoint was neurological injury at discharge according to cerebral performance category score. Overall, mean HR was 95.6 beats/min. There were several significant differences in patient characteristics, indicating poor general condition of patients with tachycardia. Mortality at 1-year was 41.6%, and neurological injury at discharge was observed in 44.1% of individuals. In the multivariate analysis, tachycardia after resuscitation was an independent predictor of both 1-year mortality (hazard ratio, 2.66; 95% CI: 1.20-5.85; P=0.03) and neurological injury at discharge (odds ratio, 2.65; 95% CI: 1.27-5.55; P=0.04). Conclusions: In patients who recovered from OHCA due to ACS, tachycardia after resuscitation predicted poor clinical outcome.