Anteroposterior pacer pad position is better than anterolateral for transcutaneous cardiac pacing.

INTRODUCTION: Transcutaneous cardiac pacing (TCP) is a lifesaving procedure for patients with certain types of unstable bradycardia. We aimed to assess the difference in the pacing thresholds between the anteroposterior (AP) and anterolateral (AL) pacer pad positions. The second aim was to characterize the severity of chest wall muscle contractions during TCP.

METHODS: In this prospective crossover trial, we enrolled patients presenting to the electrophysiology laboratory for elective cardioversion. After successful cardioversion, sedated participants were sequentially paced in both positions. The study procedure concluded after successful capture or inability to achieve capture by 140 mA (the pacer's maximum output) in both positions. Pacing thresholds were compared between positions, using a student's paired t-test, assigning a value of 141 mA to any trials with non-capture.

RESULTS: Forty-one patients were screened; 20 were enrolled in the study. Seven participants were excluded from the paired analysis (three were prevented from pacing in the second position at the anesthesiologist's discretion, and 4 did not capture in either position). The study population consisted of 14 men and 6 women with a median age of 65 years. The mean pacing threshold was 33 mA lower (P = 0.001, 95% CI 20-45) in the AP (93 mA) versus the AL (126 mA) position. The median contraction severity score was 3 in the AL position versus 4 in the AP position (P = 0.005).

CONCLUSIONS: Placing pacer pads in the AP position requires less energy to capture. Major resuscitation guidelines may favor the AP position for TCP.

CLINICALTRIALS: gov Identifier: NCT03898050 https://clinicaltrials.gov/ct2/show/NCT03898050.