Objective: To explore the predictive value of the impedance measured during leadless pacemaker Micra implantation on the trend of changes of pacing threshold post implantation. Methods: This is a retrospective cross-sectional study. Patients who received implantation of leadless pacemaker Micra at the Second Xiangya Hospital of Central South University from December 2019 to August 2020 were enrolled. The clinical data and the intraoperative electrical parameters during leadless pacemaker implantation were collected. The impedance and pacing threshold data were analyzed at three time points: immediate release, 5-10 min after release, and after traction test. Receiver operating characteristic (ROC) curves and the area under the curve (AUC) were used to analyze the value of the impedance at immediate release on predicting the trend of changes of pacing threshold post implantation. Results: A total of 21 patients (mean age: (72.2±12.5) years, 12 males) were included. The impedance of 21 patients was (798.1±35.3) Ω immediately after implantation, (800.9±35.6) Ω after 5-10 minutes of release, and (883.6±31.7) Ω after traction test. Impedance was similar between the three time points (P>0.05). The threshold was (0.97±0.11) V/0.24 ms immediately after implantation, (0.95±0.12) V/0.24 ms at 5-10 min after the release, and (0.59±0.06) V/0.24 ms after the traction test. The threshold was significantly lower after the traction test than that immediately after release (P=0.003) and than that at 5-10 minutes after release (P=0.008), suggesting a decreased tendency of the threshold over time. According to the analysis of the ROC curve, the immediate impedance after the release ≥680 Ω could predict the ideal pacing threshold after the traction test (AUC=0.989, 95%CI 0.702-0.964, P<0.001), the prediction sensitivity was 87%, and the specificity was 100%. The pacing threshold would be not ideal with the immediate impedance ≤ 520 Ω (95%CI 0.893-1.000, P<0.001), the sensitivity was 100%, and the specificity was 80%. Conclusions: The impedance immediately after the release has predictive value for the changing trend of threshold post leadless pacemaker Micra implantation. Impedance ≥680 Ω immediately after release is often related with ideal pacing threshold after the traction test. In contrast, the impedance ≤ 520 Ω pacing is often related with unsatisfactory threshold after the traction test, therefore, it is recommended to find a new pacing site to achieve the impedance ≥680 Ω immediately after release during leadless pacemaker Micra implantation.
目的： 初步探讨无导线起搏器Micra置入术中释放即刻阻抗对起搏阈值变化趋势的预测价值。 方法： 本研究为回顾性、横断面研究，选取2019年12月—2020年8月在中南大学湘雅二医院接受无导线起搏器Micra置入的患者，收集患者基本临床资料、无导线起搏器置入术中电学参数，将阻抗和起搏阈值分为释放即刻、释放后5~10 min和牵拉试验后3组。采用重复测量方差分析统计对比3组电学参数，绘制受试者工作特征（ROC）曲线并根据曲线下面积（AUC）分析释放即刻阻抗对起搏阈值变化趋势的预测价值。 结果： 共纳入21例置入Micra无导线起搏器的患者，男性12例（57%），年龄（72.2±12.5）岁。21例患者置入术中释放即刻阻抗为（798.1±35.3）Ω，释放后5~10 min为（800.9±35.6）Ω，牵拉试验后为（883.6±31.7）Ω，3组阻抗间的差异无统计学意义（P>0.05）。释放即刻阈值为（0.97±0.11）V/0.24 ms，释放后5~10 min为（0.95±0.12）V/0.24 ms，牵拉试验后为（0.59±0.06）V/0.24 ms，牵拉试验后阈值低于释放后即刻（P=0.003）和释放后5~10 min（P=0.008），阈值有随时间推移而降低的趋势。ROC曲线分析显示，释放即刻阻抗≥680 Ω可预测牵拉试验后能获得理想的起搏阈值（AUC=0.989，95%CI 0.702~0.964，P<0.001），预测敏感度为87%，特异度为100%；而释放即刻阻抗≤520 Ω时起搏阈值不理想（95%CI 0.893~1.000，P<0.001），且不能随时间推移而改善，敏感度为100%，特异度为80%。 结论： Micra无导线起搏器释放即刻的阻抗值对起搏阈值的变化趋势有预测价值，释放即刻阻抗≥680 Ω提示牵拉试验后获得理想的起搏阈值可能性较高，而阻抗≤520 Ω起搏预测阈值不良，建议寻找新的起搏位点。.