P6478Time-course of left ventricle function during mild therapeutic hypothermia in out-of-hospital cardiac arrest patients

Abstract

Background: Mild therapeutic hypothermia (MTH) is used to improved outcomes in comatose survivors of out-of-hospital cardiac arrest (OHCA). However, the time-course of left ventricle (LV) function and predictors of early improvement in LV function remain unknown. Purpose: To evaluate LV ejection fraction (EF) and global longitudinal strain (GLS) on admission, during MTH and 24 hours after rewarming in OHCA patients by serial transthoracic echocardiography. Methods: This is a substudy of a randomized trial evaluating xenon anaesthesia after cardiac arrest. Thirty-eight adult OHCA survivors with ventricular fibrillation or pulseless ventricular tachycardia as initial cardiac rhythm were studied. Pa-tients received MTH with a target temperature of 33°C for 24 hours. Echocardio-graphy (GE Vivid 9 or i) was done on admission to hospital, during MTH (24±4 hours after reaching the target temperature), and 24 hours after rewarming to assess EF (Simpson's method) and GLS. Patients were divided in two groups according to improved EF (>5%, n=19) or no improvement in EF (<5%) from hospital arrival until 24 hours after rewarming. Results: Mean age of patients included was 58±11 years, 70% were male, 39% with STEMI, and average time to return of spontaneous circulation 24±6 min. Compared with on arrival to hospital, there was significant improvements in EF (39±10% vs. 45±4%, p=0.007) and GLS (-8.5±3.8% vs.-12.2±4.0%, p=0.0002) 24 hours after rewarming. During MTH, EF was comparable to that on arrival (42±12% p=0.15), but GLS had already improved (-10.6±2.6%, p=0.02). Compared with patients with no improvement in EF, patients who improved EF by >5% had lower EF (43±10% vs. 33%±8%, p=0.004) and GLS (-10.0±3.4% vs.-7.0±3.4%, p=0.008) on admission, but those were comparable during MTH (EF 41±11% vs. 44±12%, p=0.28 and GLS-11±4% vs.-11±4%, p=0.45) and after rewarming (EF 43±9% vs. 47±12%, p=0.20 and GLS-11±4% vs.-13±5%, p=0.26). There were no significant differences in the number of STEMI patients (p=0.74), the number of patients those had an angiography procedure (p=0.78), and mean arterial pressure (p=0.2) among the groups. Conclusion: There is a significant improvement in LV systolic function after OHCA. Most of the improvement in EF and GLS occur during the first 24 hours after admission and EF and GLS during MTH appear to be predictive of LV function after rewarming. Funding Acknowledgements: The Academy of Finland.