Lung Diffusion Capacity Affects Stroke Volume in Systemic Sclerosis

Abstract Objective: In our previous cross-sectional study, we reported impaired stroke volume in patients with systemic sclerosis; however, no cardiac parameter using echocardiography was found to be related to stroke volume reduction. As few studies have focused on the hemodynamic clinical course, the patients were re-evaluated in a median interval of 18 months, and correlations between stroke volume and cardiopulmonary parameters were analyzed. Results: Seventeen patients who were able to complete the 6-minute walk test wearing a non-invasive impedance cardiograph device were assigned for re-evaluation, and individual changes in the stroke volume were noted. The stroke volume was not related to cardiac parameters, but it was significantly related to the diffusion capacity of the lung for carbon monoxide after walking in the first evaluation (r = 0.63, p = 0.006), and at rest in the re-evaluation (r = 0.72, p = 0.001). Significant relation was also found between the distance walked and the stroke volume after walking in the first evaluation and re-evaluation, and at rest in the re-evaluation. Thus, a limited lung diffusion capacity may affect stroke volume due to the exercise intolerance in systemic sclerosis without pathological heart involvement.