Abstract: Objective: Cardiopulmonary exercise testing (CPET) was used to investigate the exercise pathophysiology of mitral regurgitation. Methods: 26 patients with moderate and severe mitral regurgitation who completed standardized extreme exercise CPET under strict quality control after signing informed consent since 2016, and 11 normal subjects in the same period as the control group. The core indexes of CPET were analyzed and calculated according to the standard method and compared with normal subjects for intergroup statistical independent sample t-test. At the same time, the patients with heart failure and exercise oscillation breathing (OB) were divided into two subgroups: 11 cases without heart failure, 15 cases with heart failure, 8 cases with non-OB and 18 cases with OB, and their similarities and differences were compared between each subgroup. Results: The core indexes of CPET, such as peak oxygen uptake (85.60 ±9.06)%pred and anaerobic threshold (AT, (87.59 ±15.38)%pred) were normal. The peak oxygen uptake of CPET in patients with mitral regurgitation was (48.15 ±12.11)%pred, peak oxygen pulse was (66.57 ±12.20)%pred, AT was (56.75 ±11.50)%pred, oxygen uptake efficiency plateau was (88.24 ±16.42)%pred , lowest value of carbon dioxide ventilatory efficiency was (125.89 ±27.05)%pred and slope of carbon dioxide ventilatory efficiency was (128.31 ±31.68)%pred. Among them, only oxygen uptake efficiency plateau (OUEP) was normal and low, and the other indexes were significantly abnormal. There were significant differences between the patients and the control group (P<0.01). There was no significant difference between the non-OB group and the OB group, but there was significant difference between the non-OB group and the control group (P<0.05). There was no significant difference between the non-heart failure group and the heart failure group, but there was significant difference between the non-heart failure group and the control group. Conclusion: All the core indexes of cardiopulmonary exercise are significantly abnormal in patients with mitral regurgitation who are significantly lower than those in normal subjects except for the low effectiveness of oxygen ventilation. And with or without heart failure and OB did not affect the cardiopulmonary function.

Key words: valvular heart disease, mitral regurgitation, cardopulmonary exercise testing, pathophysiology