Advanced cardiac life support (ACLS) guidelines allow various treatments for stable monomorphic ventricular tachycardia (VT). Research on this topic has been limited by the transient nature of this rhythm, hence most studies have small sample sizes and are difficult to reproduce. The purpose of this study is to compare the relative effectiveness and safety of initial therapies used to treat stable VT across 21 community emergency departments (EDs). This retrospective cohort study used structured chart review of all treated adults with ED presentations for prolonged (>2 min) monomorphic VT in 21 community EDs from 01/2010 through 12/2017. We defined monomorphic VT as a regular wide complex tachycardia (WCT) with QRS >120 ms and rate >120 beats/min. Supraventricular tachycardia with aberrancy was excluded based on Brugada criteria for VT and confirmed by the cardiology consult obtained during the patient encounter. We excluded unstable patients defined as those with an abnormal level of consciousness, dyspnea at rest, severe anginal symptoms, or physician documentation of instability. We used descriptive statistics and reported results at the patient encounter level. We described the incidence of initial treatments, successful termination (defined as VT termination within 20 minutes lasting >30 min), ED cardiac arrest following the initial intervention, and death. We compare outcomes using a two-tailed chi-square test. We analyzed 359 eligible ED presentations from 339 patients. Mean age was 70.0 years and 22.3% of cases were female: 125 (34.8%) had an automated implantable cardioverter-defibrillator (AICD), 185 (51.5%) had congestive heart failure, and 122 (34.0%) were taking chronic antiarrhythmic medications. WCT was evaluated with adenosine in 40 cases (11.1%). Initial VT treatments were intravenous amiodarone (n=196, 54.6%), external direct-current cardioversion [DCC] (n=88, 24.5%), lidocaine (n=30, 8.4%), AICD shock (n=14, 3.9%), procainamide (n=3, 0.8%), and other treatments (n=28, 7.8%). We report initial treatment success in the Table. DCC was significantly more effective than amiodarone (81.8% vs 37.2%; p<0.0001). Overall, 160 presentations (45.1%) required multiple treatments prior to ED disposition. Cardiac arrest was uncommon in this study (2.7%) and could not be associated with specific interventions due to small sample size. Five patients (1.5%) suffered cardiac arrest after the initial ED intervention, four others (1.2%) suffered cardiac arrest in the ED after subsequent interventions, one of whom died in the ED prior to disposition. Emergency physicians use a variety of treatments for stable monomorphic VT with differing rates of success. Amiodarone is the most common initial treatment, but it may be less effective than DCC. Because initial treatments are often ineffective, patients frequently require multiple interventions. Opportunities exist for improvements in care.