目的 探讨心率减速力（deceleration capacity of heart rate，DC）预测曲妥珠单抗辅助治疗人 表皮生长因子受体 2（human epidermal growth factor receptor 2，HER2）阳性乳腺癌所致心脏毒性的临床应 用价值。方法 回顾性研究 2015 年 6 月至 2017 年 6 月在我院接受曲妥珠单抗辅助治疗 HER2 阳性乳腺 癌患者。用药前通过 24 h 动态心电图检测计算 DC 和超声心动图测量左心室射血分数（left ventricular ejection fraction，LVEF）评估心脏功能基线水平。用药期间及用药结束后有定期随访心脏毒性相关临床 症状及检测 LVEF 完整资料。结果 符合入组患者 150 例，其中 28 例（18.7%）出现心脏毒性。与无心脏 毒性组相比，有心脏毒性组的年龄较大（P = 0.018）、蒽环类药物治疗剂量更高（P＜0.001）、治疗前 的 DC 和 LVEF 较低（P＜0.001）。Logistic 回归分析结果显示，蒽环类药物高治疗剂量、治疗前较低的 DC 及 LVEF 是曲妥珠单抗相关心脏毒性的独立危险因素。受试者工作特征（ROC）分析显示，DC 的曲线 下面积比基线 LVEF 大（0.875 vs. 0.763，P = 0.032）。结论 DC 在曲妥珠单抗相关心脏毒性中有早期预 测作用。

Objective Early predictors of trastuzumab ⁃ related cardiotoxicity are urgently needed. There⁃ fore，we investigated the clinical value of the deceleration capacity of the heart rate（DC）in predicting trastuzumab⁃ related cardiotoxicity in the treatment of human epidermal growth factor receptor 2（HER2）⁃positive breast cancer. Methods Patients with HER2⁃positive breast cancer treated with trastuzumab at our hospital from June 2015 to June 2017 were retrospectively observed. DC was assessed before treatment ，and the left ventricular ejection fraction（LVEF）was regularly monitored for 2 years（before，during，and after treatment）to evaluate the develop⁃ ment of cardiotoxicity. Results Among 150 eligible patients with complete datasets，28（18.7%）developed cardiotoxicity. The age of patients with cardiotoxicity were older（P = 0.018），the anthracycline dose they received was higher（P < 0.001），and DC and baseline LVEF they had were lower（P < 0.001），compared with those in patients without cardiotoxicity. Logistic regression revealed that lower DC，lower baseline LVEF，and higher anthra⁃ cycline dose were independent risk factors of trastuzumab ⁃ related cardiotoxicity. Receiver operating characteristic curve analysis revealed a greater area under the curve for DC than for the baseline LVEF in predicting cardiotoxicity （0.875 vs. 0.768，P = 0.032）. Conclusion DC should be an early predictor of trastuzuma⁃related cardiotoxicity