Anteroposterior versus anterolateral pacer pad position in patients with symptomatic bradycardia

Introduction: Transcutaneous cardiac pacing (TCP) is an important emergency treatment option in patients with symptomatic bradycardia. With the help of a portable pulse generator an electrical current is delivered through the patient́s thorax in order to induce ventricular contractions. Data on patients in sinus rhythm suggests favorable pacing thresholds when using an anteroposterior (AP) compared to an anterolateral (AL) pacer pad positioning. However, evidence in bradycardic patients is lacking. Methods: We conducted a prospective crossover clinical study which included 16 patients with symptomatic bradycardia. Patients received consecutive TCP in an AP and AL position under sedoanalgesia. TCP was carried out in an AP and an AL pacer pad position if patients were hemodynamically stable (systolic blood pressure > 90 mmHg). Minimal required current and other variables were noted for both pacer pad positions and Wilcoxon Signed Rank tests were used to compare differences. Results: We did not overserve a significant difference in minimal required pacing current between the AP and AL pacer pad position (median threshold AP = 125 mA [±48], median threshold AL = 140 mA [±78], p = 0.53). However, a linear mixed-effects model revealed higher pacing thresholds in patients on beta blockers (B = 72.1, p < 0.001, 95 % CI = 36.6-107.7) and with lower myocardial mass (B = -0.41, p < 0.001, 95 % CI = -0.59- -0.23). Conclusion: We observed no significant difference in pacing thresholds between an AP and AL pacer pad position in patients with symptomatic bradycardia. These results do not align with prior work investigating a monitor with pulsed current delivery.