Influence of disease-related heart pathology on peak oxygen uptake and ventilation/carbon dioxide output ratio in systemic sclerosis and systemic lupus erythematosus patients (RCD code: I-3C)

Abstract

Background: Exercise capacity is an independent predictor of mortality in the general population. However, available literature has been focused mainly on exercise testing in patients with ischaemic heart failure. Little is known about such testing in generalized autoimmune diseases with their different pathogenesis and sex prevalence. The aim of the study was to assess the influence of disease‑related heart pathology on exercise capacity evaluated by cardiopulmonary exercise (CPX) test in systemic sclerosis (SSc) and systemic lupus erythematosus (SLE) patients. Methods: Echocardiography and CPX test were performed in 46 SSc patients, 60 SLE patients and 30 healthy controls. Results: Echocardiography showed normal left ventricle systolic function in all subjects except for 2 (3,3%) SLE patients with enlarged left ventricle. In contrast, diastolic left ventricular dysfunction was found in all SSc patients and in 13 (21,7%) SLE patients. Right ventricle systolic pressures were elevated (>30 mmHg) in 14 (30,4%) SSc and 10 (16,7%) SLE patients. Valvular leaflet or pericardium thickening was observed in 17 (37,0%) SSc and in 38 (63,3%) SLE patients. CPX test showed low exercise capacity in 36 (78,3%) SSc patients, while mean values of gas exchange parameters remained normal in SLE and control groups. In SSc time of exercise was significantly shorter and peak oxygen uptake decreased as compared to healthy subjects (13,1 ±4,8 min vs. 17,8 ±2,6 min, p = 0,01 and 16,51 ±6,86 ml/kg/min vs. 25,66 ±6,62 ml/kg/min, p = 0,001, respectively). Ventilation/carbon dioxide output ratio (VE/VCO2) was increased (>34) in 32 (69,6%) SSc and 4 (6,7%) SLE patients. Weber C or D class of cardiopulmonary failure (severe or end‑stage, VO2peak < 15 ml/kg/min) was observed in 20 (43,5%) SSc and only in 2 (3,4%) SLE patients. Conclusions: Exercise intolerance expressed by VO2peak < 15 ml/kg/min and VE/VCO2 > 34 was present in almost half of SSc patients, while severely impaired gas exchange parameters were very rare in SLE. Exercise capacity test may then serve as an important non‑invasive prognostic parameter in SSc. In contrast, in SLE prognostic value of CPX would be probably of lesser clinical importance as its abnormal values seem to be rare in this entity. JRCD 2013; 1 (3): 10–16