104 Cardioversion of Recent-Onset Atrial Fibrillation and Flutter in the Emergency Department: Relationship of Energy Level and Success

Abstract

Emergency department cardioversion (EDC) of recent onset atrial fibrillation and flutter (AF) is an accepted management approach to patients with these arrhythmias. The ideal energy level for direct current (DC) cardioversion of AF patients has not been reported for the ED. This study examines the associations between energy levels and EDC success. Patients undergoing EDC were identified though a query of hospital and ED electronic health data bases. Patient records were abstracted for cardiac rhythm, number of cardioversion attempts, joules per attempt, and post conversion rhythms. All cardioversions were performed with the same model Biphasic Defibrillator. A total of 348 patients underwent emergency department cardioversion for AF over a 64-month period, 306 with atrial fibrillation and 42 with atrial flutter. Of the fibrillation patients 271 (88.6%) were successfully converted to normal sinus Rhythm compared to 40 (95.2%) of the Flutter patients. (p=0.149) Four patients had incomplete documentation of number of cardioversion attempts or joules used and were excluded from further analysis. Overall 262 (86.8%) of fibrillation patients received a single DC shock compared to 40 (95%) of flutter patients (p=0.26). Additional EDC attempts for fibrillation patients included: 2 attempts in 29 (9.6%) and 3 attempts in 11 (3.6%). For the flutter patients 1 (2.4%) received 2 attempts and 1 (2.4%) received 3 attempts. The most common initial energy level for fibrillation patients was 200 joules used in 278 (92.0%) cases, with the same initial energy level used in 37 (88.1%) Flutter patients (p=0.50). For fibrillation patients receiving a second EDC attempt the most common energy selected was again 200 joules used in 21 (52%) of patients while in those receiving 3 EDC’s, 4 (36%) received 300 joules, 4 (36%) received 300 joules, 2 (18%) received 200 joules and 1 (9%) received 285 joules. For the 2 multiple EDC flutter patients, 1 second attempt was at 250 joules and the other at 300 joules. The single flutter patient undergoing a third shock received it at 360 joules. The conversion to normal sinus rhythm success for different energy levels and attempts for atrial fibrillation is presented in Table 1. Atrial flutter cases are not include in the table because all but 2 cases were converted at 200 joules or less. For patients undergoing emergency department cardioversion for atrial fibrillation or flutter an initial attempt at 200 joules should be considered. If unsuccessful then repeat attempts should consider energy levels over 300 joules.Tabled 1Conversion Success Rates For Energy Levels For Atrial FibrillationCardioversion Success (%)<200 j200 j201-299 j300-360 jp valueFirst Attempt2 (60%)232 (95.9%)4 (100%)11 (100%)0.008Second Attempt05 (38.5%)5 (71.4%)5 (55%)0.35Third Attempt01 (50%)03 (37.3%)0.69 Open table in a new tab