Abstract
BACKGROUND: Scleroderma is a connective tissue disorder characterized by reduced exercise tolerance. The aim of the study is: (I) to estimate the prevalence of decreased maximum exercise capacity, (II) to investigate the cause of this functional limitation (respiratory or cardiovascular disorders) and (III) to study potential differences of clinical, radiological, functional characteristics and blood serology among scleroderma patients with functional limitation of different etiology. MATERIAL AND METHODS: A consecutive population of 82 scleroderma patients (11.9% male; 49.8 years old and 88.1% female; 54.9 years old), who were evaluated at the respiratory physiology laboratory of the Respiratory Failure Unit, constituted the study population. Patients underwent spirometry, measurement of diffusion capacity, resting Doppler echocardiography and maximum cardiopulmonary exercise testing on a cycle ergometer. Data on previous thorax computed tomography and blood serology were also recorded. Breathing Reserve at the end of exercise was calculated as: BR = (FEV(1) ×40) - peak minute ventilation. Patients with BR <11 lt presented with respiratory limitation, the ones with peak oxygen uptake (VO(2) max%) <75% predicted presented with circulatory limitation, while the ones with both BR ≥11 lt and VO(2) max% ≥75% presented with normal maximum exercise capacity. RESULTS: Exercise capacity was normal in 37.8% of patients (group N), reduced exercise capacity due to respiratory limitation in 12.2% (group R) and reduced exercise capacity due to circulatory limitation in 50% (group C). Patients of group R, compared to those of group C, were older (61.3 vs. 48.3 years old; P=0.018), had a more severe respiratory restriction (measured by TLC%) (61.3 vs. 84.5; P<0.001), presented with pulmonary hypertension less often (P=0.048) and reached a lower VO(2) max% (67.8% vs. 71.1%). Neither autoantibodies subtype (Anti sc70 or ACA), nor systemic arterial pressure during exercise differed between the two groups. Conclusions: Reduced exercise capacity occurs very often among patients with scleroderma. The most common cause is circulatory limitation, while the less frequent respiratory limitation occurs among older patients with more severe lung involvement.