MacDonald David M, Helgeson Erika S, Adabag Selcuk, Casaburi Richard, Connett John E, Stringer William W, Voelker Helen, Dransfield Mark T, Kunisaki Ken M
Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, and.
Division of Biostatistics, University of Minnesota, Minneapolis, Minnesota.
Ann Am Thorac Soc. 2021 Nov;18(11):1795-1802. doi: 10.1513/AnnalsATS.202008-1085OC.
The chronotropic index quantifies the proportion of the expected heart rate increase that is attained during exercise. The relationship between the chronotropic index and acute exacerbations of chronic obstructive pulmonary disease (AECOPDs) has not been evaluated. To determine whether a higher chronotropic index during a 6-minute walk (CI-6MW) is associated with lower risk of AECOPD and whether the CI-6MW is a marker of susceptibility to adverse effects of metoprolol in chronic obstructive pulmonary disease (COPD). We analyzed data from the BLOCK COPD (Beta-Blockers for the Prevention of AECOPDs) trial. We used Cox proportional hazards models to investigate the relationship between the CI-6MW and the time to AECOPDs. We also tested for interactions between study group assignment (metoprolol vs. placebo) and the CI-6MW on the time to AECOPDs. Four hundred seventy-seven participants with exacerbation-prone COPD (mean forced expiratory volume in 1 second, 41% of predicted) were included in this analysis. A higher CI-6MW was independently associated with a decreased risk of AECOPDs of any severity (adjusted hazard ratio per 0.1 increase in CI-6MW of 0.88; 95% confidence interval, 0.80-0.96) but was not independently associated with AECOPDs requiring hospitalization (adjusted hazard ratio, 0.94; 95% confidence interval, 0.81-1.05). There was a significant interaction by treatment assignment, and in a stratified analysis, the protective effects of a higher CI-6MW on AECOPDs were negated by metoprolol use. A higher CI-6MW is associated with a decreased risk of AECOPDs and may be an indicator of susceptibility to the adverse effects of metoprolol.
变时指数量化了运动期间预期心率增加所达到的比例。变时指数与慢性阻塞性肺疾病急性加重（AECOPD）之间的关系尚未得到评估。为了确定6分钟步行期间较高的变时指数（CI-6MW）是否与较低的AECOPD风险相关，以及CI-6MW是否是慢性阻塞性肺疾病（COPD）患者对美托洛尔不良反应易感性的标志物。我们分析了BLOCK COPD（预防AECOPD的β受体阻滞剂）试验的数据。我们使用Cox比例风险模型来研究CI-6MW与发生AECOPD的时间之间的关系。我们还测试了研究组分配（美托洛尔与安慰剂）和CI-6MW对发生AECOPD时间的交互作用。本分析纳入了477名易发生加重的COPD患者（平均1秒用力呼气量为预测值的41%）。较高的CI-6MW与任何严重程度的AECOPD风险降低独立相关（CI-6MW每增加0.1，调整后的风险比为0.88；95%置信区间为0.80-0.96），但与需要住院治疗的AECOPD无独立相关性（调整后的风险比为0.94；95%置信区间为0.81-1.05）。治疗分配存在显著交互作用，在分层分析中，美托洛尔的使用抵消了较高CI-6MW对AECOPD的保护作用。较高的CI-6MW与AECOPD风险降低相关，可能是对美托洛尔不良反应易感性的一个指标。
