Anterior-Lateral Versus Anterior-Posterior Electrode Position for Cardioverting Atrial Fibrillation

Background: Smaller randomized studies have reported conflicting results regarding the optimal electrode position for cardioverting atrial fibrillation. However, anterior-posterior electrode position is widely used as a standard and believed to be superior to anterior-lateral electrode position. Therefore, we aimed to compare anterior-lateral and anterior-posterior electrode position for cardioverting atrial fibrillation in a multicenter randomized trial. Methods: In this multicenter, investigator-initiated, open-label trial, we randomly assigned patients with atrial fibrillation scheduled for elective cardioversion to anterior-lateral or anterior-posterior electrode position. The primary outcome was the proportion of patients in sinus rhythm after the first shock. The secondary outcome was the proportion of patients in sinus rhythm after up to four shocks escalating to maximum energy. Safety outcomes were any cases of arrhythmia during or after cardioversion, skin redness, and patient-reported peri-procedural pain. Results: We randomized 468 patients. The primary outcome occurred in 126 patients (54%) assigned to anterior-lateral electrode position and in 77 patients (33%) assigned to anterior-posterior electrode position, a risk difference of 22 percentage-points, 95%-confidence interval: 13-30, P<0.001. The number of patients in sinus rhythm after the final cardioversion shock was 216 patients (93%) assigned to anterior−lateral electrode position and 200 patients (85%) assigned to anterior-posterior electrode position, a risk difference of 7 percentage−points, 95%−confidence interval: 2−12. There were no significant differences between groups in any safety outcomes. Conclusions: Anterior-lateral electrode position was more effective than anterior-posterior electrode position for biphasic cardioversion of atrial fibrillation. There were no significant differences in any safety outcome.

Maintenance of relational information in working memory leads to suppression of the sensory cortex

Working memory (WM) for sensory-based information about individual objects and their locations appears to involve interactions between lateral prefrontal and sensory cortexes. The mechanisms and representations for maintenance of more abstract, nonsensory information in WM are unknown, particularly whether such actively maintained information can become independent of the sensory information from which it was derived. Previous studies of WM for individual visual items found increased electroencephalogram (EEG) alpha (8–13 Hz) power over posterior electrode sites, which appears to correspond to the suppression of cortical areas that represent irrelevant sensory information. Here, we recorded EEG while participants performed a visual WM task that involved maintaining either concrete spatial coordinates or abstract relational information. Maintenance of relational information resulted in higher alpha power in posterior electrodes. Furthermore, lateralization of alpha power due to a covert shift of attention to one visual hemifield was marginally weaker during storage of relational information than during storage of concrete information. These results suggest that abstract relational information is maintained in WM differently from concrete, sensory representations and that during maintenance of abstract information, posterior sensory regions become task irrelevant and are thus suppressed.