Assessing Dynamic Atrioventricular Conduction Time to RR-interval Coupling in Athletes and Sedentary Subjects

Abstract Background Atrioventricular conduction time ( AVCT ) is influenced by autonomic input and subject to physiological remodeling. Objective To evaluate beat-by-beat AVCT and RR-interval variability in athletes and healthy sedentary subjects. Methods Twenty adults, including 10 healthy sedentary (Controls) and 10 elite long-distance runners (Athletes), age, weight and height-adjusted, underwent maximal metabolic equivalent (MET) assessment, and 15-min supine resting ECG recording seven days later. The interval between P-wave and R-wave peaks defined the AVCT . Mean (M) and standard deviation (SD) of consecutive RR-intervals (RR) and coupled AVCT were calculated, as well as regression lines of RR vs. AVCT (RR-AVCT) . Concordant AV conduction was defined as positive RR-AVCT slope and discordant otherwise. A multivariate linear regression model was developed to explain MET based on AVCT and RR-interval variability parameters. Significance-level: 5 %. Results In Athletes, M-RR and SD-RR values were higher than in Controls, whereas M-AVCT and SD-AVCT were not. RR-AVCT slopes were, respectively, 0.038 ± 0.022 and 0.0034 ± 0.017 (p &lt; 0.05). Using a cut-off value of 0.0044 (AUC 0.92 ± 0.07; p &lt; 0.001), RR-AVCT slope showed 100% specificity and 80% sensitivity. In a multivariate model, SD-RR and RR-AVCT slope were independent explanatory variables of MET (F-ratio: 17.2; p &lt; 0.001), showing 100% specificity and 90% sensitivity (AUC 0.99 ± 0.02; p &lt; 0.001). Conclusion In elite runners, AVCT to RR -interval dynamic coupling shows spontaneous discordant AV conduction, characterized by negative AVCT vs. RR -interval regression line slope. RR -intervals standard deviation and AVCT vs. RR -interval regression line slope are independent explanatory variables of MET (Arq Bras Cardiol. 2020; [online].ahead print, PP.0-0)【摘要 背景】房室传导时间（Atrioventricular conduction time, AVCT）受自主神经输入调控，且可发生生理性重塑。 【研究目的】评估运动员与健康久坐受试者的逐搏房室传导时间与RR间期变异性。 【研究方法】本研究纳入20名成年人，包括10名健康久坐者（对照组）与10名精英长跑运动员（运动员组），经年龄、体重、身高校正后，完成最大代谢当量（Metabolic Equivalent, MET）评估，并于7天后进行15分钟仰卧静息心电图（Electrocardiogram, ECG）记录。以P波（P-wave）峰值与R波（R-wave）峰值之间的间期定义为房室传导时间。计算连续RR间期（RR）与配对房室传导时间的均值（Mean, M）与标准差（Standard Deviation, SD），并构建RR与AVCT的回归直线（RR-AVCT）。当RR-AVCT斜率为正时，定义为一致性房室传导，反之则为非一致性房室传导。构建多元线性回归模型，基于AVCT与RR间期变异性参数解释MET水平，显著性水平设定为5%。 【研究结果】运动员组的M-RR与SD-RR值均高于对照组，但M-AVCT与SD-AVCT值无组间差异。两组RR-AVCT斜率分别为0.038±0.022与0.0034±0.017（p<0.05）。以0.0044为截断值时，曲线下面积（Area Under the Curve, AUC）为0.92±0.07（p<0.001），此时RR-AVCT斜率的特异性为100%，灵敏度为80%。在多元回归模型中，SD-RR与RR-AVCT斜率为MET的独立解释变量（F值：17.2；p<0.001），该模型的特异性为100%，灵敏度为90%（AUC=0.99±0.02；p<0.001）。 【研究结论】精英长跑运动员的AVCT与RR间期动态耦合表现为自发性非一致性房室传导，其特征为AVCT与RR间期的回归直线斜率为负值。RR间期标准差及RR-AVCT回归直线斜率是MET的独立解释变量。(Arq Bras Cardiol. 2020; [online].ahead print, PP.0-0)