Abstract 14773: Association of First Documented Rhythms With Clinical Outcomes Among Adult Witnessed OHCA Patients: JCS-Ress Study.

Background: While studies have shown that the first documented rhythm is associated with clinical outcome in patients with cardiac arrest, little is known about the difference in clinical outcomes between two types of shockable rhythm (i.e., pulseless ventricular tachycardia [p-VT] and ventricular fibrillation [VF]) among patients with out-of-hospital cardiac arrest (OHCA). Methods: Using a nationwide, prospective population-based OHCA database from 2011 to 2015, we included witnessed adult (aged ≥18 years) patients. Patients who were used public-automated external defibrillator were excluded because of the unavailability of the first documented rhythm. The primary outcome was favorable 30-day neurological survival. To determine the association of the first documented rhythm with outcome, we used logistic regression model with adjustment for patient-level factors (age, sex, etiology of OHCA and incidence year) and prehospital care-related factors (type of witness, bystander cardiopulmonary resuscitation status, and time interval from collapse to the first defibrillation). Results: A total of 22,506 witnessed OHCA patients (median age, 68 years; male, 77%) having shockable rhythm as the first documented rhythm were included: 809 (3.6%) were p-VT and 21,697 (96.4%) were VF. Compared to VF patients, p-VT patients were older (median, 77 years vs. 67 years, p<0.0001), less likely to be male (61.6% vs. 77.6%, P<0.001), less likely to be cardiogenic (69.3% vs. 89.0%, p<0.001), more likely to be witnessed by EMS personnel (43.1% vs. 11.1%, P<0.001) and had shorter time from collapse to the first defibrillation (median, 6 min vs. 11 min, p<0.001). P-VT patients had a higher ROSC rate (40.2% vs. 33.9%, P<0.001), but there was no difference in favorable 30-day neurological survival (23.4% vs. 22.1%, P=0.38). After adjustment for patient-level and prehospital care-related factors, p-VT was associated with better ROSC and favorable 30-day neurological survivalrates with corresponding adjusted odds ratios of 1.86 (95% CI, 1.52-2.27, P<0.001) and 1.59 (95% CI 1.27-1.99, P<0.001). Conclusion: In this nation-wide population-based study of OHCA, patients with p-VT as the first documented rhythm had significantly better outcome compared to those with VF. [ABSTRACT FROM AUTHOR]