External
cardioversion is an established and very important tool to terminate symptomatic
atrial flutter. The superiority of the biphasic waveform has been demonstrated for
atrial flutter, but whether
electrode position affects the efficacy of
cardioversion in this population is not known. The aim of this trial was to evaluate whether anterior-lateral (A-L) compared with anterior-posterior (A-P)
electrode position improves
cardioversion results. Of 130 screened patients, 96 (72 men, mean age 62 +/- 12 years) were included and randomly assigned to a
cardioversion protocol with either A-L or A-P
electrode position. In each group, 48 patients received sequential biphasic waveform shocks using a step-up protocol consisting of 50, 75, 100, 150, or 200 J. The mean energy (65 +/- 13 J for A-L vs 77 +/- 13 J for A-P, p = 0.001) and mean number of shocks (1.48 +/- 1.01 for A-L vs 1.96 +/- 1.00 for A-P, p = 0.001) required for successful
cardioversion were significantly lower in the A-L group. The efficacy of the first
shock with 50 J in the A-L
electrode position (35 of 48 patients [73%]) was also highly significantly greater than the first
shock with 50 J in the A-P
electrode position (18 of 48 patients [36%]) (p = 0.001). In conclusion, the A-L
electrode position increases efficacy and requires fewer energy and shocks in external
electrical cardioversion of common
atrial flutter. Therefore, A-L
electrode positioning should be recommended for the external
cardioversion of common
atrial flutter.