Safety, Efficacy, and Dose Protocol of Metoprolol for Heart Rate Reduction in Pediatric Outpatients Undergoing Cardiac CT Angiography

Abstract Background Image quality and radiation dose are optimized with a slow, steady heart rate (HR) when imaging the coronary arteries during cardiac computed tomography angiography (CCTA). The safety, efficacy, and protocol for HR reduction with beta blocker medication is not well described in a pediatric patient population. Objective Provide a safe and efficient metoprolol dose protocol to be used in pediatric outpatients undergoing CCTA. Methods We conducted a retrospective review of all pediatric outpatients who received metoprolol during CCTA. Demographic and clinical characteristics were summarized and the average reduction in HR was estimated using a multivariate linear regression model. Images were evaluated on a 1-4 scale (1= optimal). Results Seventy-eight pediatric outpatients underwent a CCTA scan with the use of metoprolol. The median age was 13 years, median weight of 46 kg, and 36 (46%) were male. The median doses of metoprolol were 1.5 (IQR 1.1, 1.8) mg/kg and 0.4 (IQR 0.2, 0.7) mg/kg for oral and intravenous administrations, respectively. Procedural dose-length product was 57 (IQR 30, 119) mGy*cm. The average reduction in HR was 19 (IQR 12, 26) beats per minute, or 23%. No complications or adverse events were reported. Conclusion Use of metoprolol in a pediatric outpatient setting for HR reduction prior to CCTA is safe and effective. A metoprolol dose protocol can be reproduced when a slower HR is needed, ensuring faster acquisition times, clear images, and associated reduction in radiation exposure in this population. (Arq Bras Cardiol. 2021; 116(1):100-105)

摘要 背景 在冠状动脉计算机断层血管造影（CCTA）成像中，平稳且缓慢的心率（HR）可优化图像质量与辐射剂量。然而，儿科人群中应用β受体阻滞剂降低心率的安全性、有效性及给药方案尚未得到充分阐述。 目的 本研究旨在为接受CCTA检查的儿科门诊患者提供安全且高效的美托洛尔给药方案。 方法 本研究对所有在CCTA检查期间接受美托洛尔治疗的儿科门诊患者开展回顾性分析。研究总结了受试者的人口学与临床特征，并通过多元线性回归模型估算了心率的平均降幅。图像质量采用1~4分进行评分（1=最优）。 结果 共计78名儿科门诊患者接受了美托洛尔辅助下的CCTA扫描。受试者中位年龄为13岁，中位体重为46kg，其中男性36例（占比46%）。口服与静脉给药的美托洛尔中位剂量分别为1.5（四分位数间距IQR：1.1, 1.8）mg/kg与0.4（IQR：0.2, 0.7）mg/kg。操作的剂量长度乘积为57（IQR：30, 119）mGy·cm。受试者的心率平均降幅为19（IQR：12, 26）次/分钟，降幅达23%。本研究未报告任何并发症或不良事件。 结论 在儿科门诊患者的CCTA检查前应用美托洛尔降低心率，具备良好的安全性与有效性。当需要维持较慢心率时，本美托洛尔给药方案可重复实施，从而缩短扫描采集时间、获得清晰图像，并降低该人群的辐射暴露量。（《巴西心脏病学档案》2021；116(1):100-105）