244: EPIDEMIOLOGY, ETIOLOGY, AND PROGNOSIS OF IN-HOSPITAL REFLEX-MEDIATED CARDIAC ARRESTS

Abstract

Introduction: Reflex syncope is common; however, little is known about the epidemiology and prognosis of reflex-mediated (or vagal-mediated) cardiac arrest (RMCA). We evaluated the incidence of RMCA among hospitalized patients and compared their outcomes to those with in-hospital cardiac arrests (IHCAs) of all other causes. We hypothesized that in-hospital RMCA is common and has a higher rate of return of spontaneous circulation (ROSC) than other IHCAs. Methods: This is a retrospective cohort study of all adult IHCAs at two large academic medical centers from January 1, 2016 to June 30, 2022. Patients were included if they had a RMCA requiring cardiopulmonary resuscitation. A RMCA was defined as the absence of a palpable pulse with antecedent hypotension and bradycardia preceded by identifiable vagal triggers and/or a characteristic prodrome. We abstracted baseline demographics and reviewed charts to confirm the reflex-mediated etiology. The primary outcome was rate of ROSC. Secondary outcomes included survival to hospital discharge and cerebral performance category (CPC) scores of 2 or less. Student’s t-test and Pearson’s chi-squared test were used for comparisons. Results: Of 1,067 IHCA patients, 47 (4.4%) experienced RMCAs. The incidence of RMCA was 0.24 per 1,000 patients discharges while IHCA was 5.43 per 1,000 patients discharges. Compared to patients with IHCA of all other causes, RMCA patients were similar in age (mean years + SD 60.8 + 16.3 vs 58.6 + 16.2, p=0.3513) and sex (male 65.9% vs 53.2%, p=0.0739). RMCAs were most frequently triggered by defecating (29.8%) and turning (17.0%); they also frequently occurred peri-procedurally (14.9%). RMCA patients were less likely to arrest in the ICU compared to other IHCAs patients (40.4% vs 57.1%, p=0.0251). ROSC occurred in 100% and they were more likely to survive to hospital discharge (85.1% vs 36.2%, p< 0.00001) and have CPC scores of 2 or less (57.4% vs 27.0%, p< 0.00001). Conclusions: In-hospital RMCA is uncommon. Compared to patients with IHCA of all other causes, RMCA patients were less likely to arrest in the ICU, reflecting lower illness acuity and thus, increased rates of ROSC, survival to hospital discharge and good neurological outcomes. Future research should identify intervenable risk factors that predispose a patient to RMCA.