Ultrasound‐Guided Pectoral Nerve Block for Cardiac Implantable Electronic Device Implantation: A Prospective Randomized Controlled Trial of Postprocedural Analgesic Benefit in an Asian Population

Background Pain after cardiac implantable electronic device (CIED) implantation remains clinically relevant and may increase postoperative analgesic requirements. Ultrasound‐guided pectoral nerve block has shown benefit in anterior chest wall procedures, but evidence during CIED implantation, particularly in Asian populations with relatively lower body mass index (BMI), remains limited. This study aimed to evaluate the efficacy and safety of ultrasound‐guided pectoral nerve block for postoperative analgesia during CIED implantation and to explore clinical factors associated with rescue analgesic use. Methods In this prospective randomized controlled trial, 660 patients undergoing CIED implantation were randomly assigned to a pectoral nerve block group or a standard‐care group, with 330 patients in each group. Postoperative pain intensity was assessed using the numeric rating scale (NRS) at 1, 2, 4, 24, and 48 h after the procedure. Longitudinal NRS trajectories were analyzed using a linear mixed‐effects model for repeated measures. Rescue analgesic use, length of hospital stay, and adverse events were compared between groups. Univariable and multivariable logistic regression analyses were performed as exploratory analyses to identify factors associated with rescue analgesic requirement. Results Procedural characteristics were comparable between groups, including procedure type, device type, procedure duration, and implant laterality. Longitudinal analysis demonstrated significantly lower postoperative NRS scores over time in the pectoral nerve block group. Pain scores were consistently lower in the block group than in the control group at 1 h (0.87 ± 0.51 vs. 2.50 ± 0.78), 2 h (1.33 ± 0.55 vs. 4.37 ± 0.89), 4 h (2.00 ± 0.83 vs. 4.37 ± 0.93), 24 h (2.27 ± 0.91 vs. 4.57 ± 0.90), and 48 h (2.03 ± 0.67 vs. 3.67 ± 0.99) (all p < 0.001). The proportion of patients requiring rescue analgesics was significantly lower in the pectoral nerve block group than in the control group (7.58% vs. 16.67%, p = 0.001). Length of hospital stay and adverse event rates were comparable between groups. In exploratory multivariable analysis, higher BMI and higher glycated hemoglobin were independently associated with greater rescue analgesic use, whereas pectoral nerve block was independently associated with a lower likelihood of rescue analgesic requirement. Conclusions Ultrasound‐guided pectoral nerve block significantly improved postoperative analgesia and reduced rescue analgesic use in patients undergoing CIED implantation without increasing adverse events. These findings support its use as an effective perioperative analgesic strategy in an Asian cohort with a relatively lower BMI profile and suggest that BMI‐related variation in analgesic requirement may remain clinically relevant even in such populations. Trial Registration: ClinicalTrials.gov ; identifier: NCT04931693