Correlation between ventricular function as assessed by echocardiography and six-minute walk test as a surrogate of functional capacity in patients with chronic obstructive pulmonary disease

Abstract

Abstract Background Exercise intolerance is common in patients with chronic obstructive pulmonary disease (COPD), which has multiple mechanisms underlying its progression. Ventricular dysfunction may play a role in the development of exercise incapacity in patients with COPD. Aim To investigate the possible contribution of left ventricular (LV) and right ventricular (RV) dysfunction (either systolic or diastolic) in development of exercise intolerance in patients with COPD. Patients and methods A total of 60 patients with diagnosis of COPD were categorized according to GOLD spirometric stage into two groups (group 1: mild to moderate COPD, and group 2: severe to very severe COPD). Both groups were evaluated by spirometry, ECG, chest radiography, routine laboratory investigation, 6-min walk test, and echocardiography including tissue Doppler imaging. Results The average age in the whole study group was 56.63 ±10.33 years. Male patients in the study were 46 (76.7%) and female patients were 14 (23.3%). Mean maximum walk distance among the whole group was 342.75±54.85 m. There was a significant correlation between 6-min walk distance and transtricuspid E velocity, tricuspid E/A, and transtricuspid deceleration time (P=0.011, 0.015, and 0.021, respectively). There was no significant correlation between 6-min walk distance and parameters of LV diastolic dysfunction. Prevalence of ventricular dysfunction was as follow: LV systolic dysfunction 3.3%, LV diastolic dysfunction 30%, RV systolic dysfunction 21%, and RV diastolic dysfunction 46%. Conclusion RV diastolic dysfunction may be a contributing factor in the progression of exercise intolerance in COPD. Although LV diastolic dysfunction may not be associated with exercise intolerance, it is still prevalent in COPD and must be assessed and managed through the course of the disease and especially during exacerbation.

Keywords

• 6-min walk test
• chronic obstructive pulmonary disease
• echocardiography
• exercise intolerance
• ventricular dysfunction