ABSTRACT
Objective:To observe the relationship of ventilatory efficiency to cardiac function, especially heart rate recovery after exercise for patients with chronic obstructive pulmonary disease (COPD). Methods:From January, 2019 to December, 2020, 190 patients with COPD were recruited for Cardiopulmonary Exercise Testing. The general condition, medical history and medication history, lung function test and parameters of Cardiopulmonary Exercise Testing were recorded. They were divided into normal group and delay group according to whether the heart rate decline more than twelve beats within a minute after Cardiopulmonary Exercise Testing. Results:There were 89 patients (46.84%) in the delay group. Compared with the normal group, the delay group were older (Z = 2.282, P < 0.05), with less ratio of force exiratory volume in the first second in prediction (FEV1.0%) (Z = 3.626, P < 0.001), maximum power (t = 5.547, P < 0.001), breath reserve (BR) (t = 2.122, P < 0.05) and higher minimum ventilation equivalent of carbon dioxide (VE/VCO2nadir) (Z = 3.296, P = 0.001). Logistic regression showed that the COPD severity, VE/VCO2nadir and BR correlated with heart rate recovery. After adjusting for gender, age, body mass index and COPD severity, VE/VCO2nadir was an independent risk factor for delayed heart rate recovery (OR = 1.203, 95%CI 1.032 to 1.873, P = 0.004), and the best cut-off point was 33.15 (AUC = 0.6387, 95%CI 0.5595 to 0.7178, P = 0.001). Conclusion:The ventilatory inefficiency may increase the risk of abnormal heart rate recovery after exercise in COPD patients.