Relative tachycardia is associated with poor outcomes in post-cardiac arrest patients regardless of therapeutic hypothermia

Abstract

Background: To investigate whether the relationship between heart rate and neurological outcome is independent of therapeutic hypothermia (TH) and whether heart rate is related to hemodynamic instability post-cardiac arrest. Methods: Retrospective review of an out-of-hospital cardiac arrest registry was performed. The primary exposure was heart rate quartiles at 24 h post-cardiac arrest. The primary outcome was a poor neurological outcome, which was defined as having a cerebral performance category (CPC) of 3-5 at 28 days. Secondary outcomes were mean blood pressure and serum lactate at 24 h and Sequential Organ Failure Assessment (SOFA) scores at admission. Results: In total, 155 patients were enrolled. The proportion of patients with a poor CPC was significantly greater in higher heart rate quartiles; similar results were observed in patients who did and did not undergo TH. Serum lactate levels at 24 h were significantly higher in the 3rd and 4th quartile groups than in the 1st quartile group. Additionally, SOFA scores were significantly higher in the 4th quartile group than in the 1st and 3rd quartile groups. Conclusions: Relative tachycardia is associated with poor neurological outcomes in post-cardiac arrest patients, independent of TH, and with higher serum lactate levels and admission SOFA scores.