Association between Cardiac Arrest Time and Favorable Neurological Outcomes in Witnessed Out-of-Hospital Cardiac Arrest Patients Treated with Targeted Temperature Management

BACKGROUND: Patients who achieve a return of spontaneous circulation (ROSC) with prolonged cardiac arrest have been recognized to have a poor prognosis. This might lead to reluctance in the provision of post-resuscitation care. Hence, we evaluated the impact of cardiac arrest time on neurologic outcomes in out-of-hospital cardiac arrest (OHCA) patients. METHODS: This cross-sectional study used a hospital-based nationwide registry of OHCAs in Korea between 2012 and 2016. All witnessed OHCA patients aged ≥ 15 years and treated with targeted temperature management were included. We collected the time from collapse to sustained ROSC, which was defined as the downtime. The primary outcome was a favorable neurological outcome at hospital discharge. A multiple logistic regression analysis was conducted to determine independent factors for primary outcome in patients with downtime > 30 minutes. RESULTS: Overall, neurologically favorable outcome rates were 30.5% in 1,963 patients. When the downtime was stratified into categories of 0–10, 11–20, 21–30, 31–40, 41–50, 51–60, and > 60 minutes according to 10-minute intervals, neurologically favorable outcome rates were 58.2%, 52.3%, 37.3%, 24.6%, 14.1%, 17.4%, and 16.7%, respectively (P < 0.001). In patients with downtime > 30 minutes, age 51–70 years (odds ratio [OR], 5.35; 95% confidence interval [CI], 2.50–11.49), age ≤ 50 years (OR, 13.16; 95% CI, 6.06–28.57), shockable rhythm (OR, 3.92; 95% CI, 2.71–5.68), bystander resuscitation (OR, 1.80; 95% CI, 1.27–2.55), cardiac cause (OR, 3.50; 95% CI, 1.69–7.25), percutaneous coronary intervention (OR, 1.82; 95% CI, 1.18–2.81), and downtime ≤ 40 minutes (OR, 2.02; 95% CI, 1.42–2.88) were associated with favorable neurological outcomes. CONCLUSION: In patients with prolonged downtime, predicting favorable neurologic outcome may be multifactorial. The cutoff value for downtime is not the only determining factor to provide post-resuscitation care.