Abstract 4381: Exercise Gas Exchange Abnormalities Indicating Early Pulmonary Vasculopathy in Patients with Scleroderma
BACKGROUND Pulmonary arterial hypertension (PAH) is a major cause of death in patients with scleroderma (SSc). Pulmonary vasculopathy, which constitutes the histologic background of PAH, likely occurs long before the development of symptoms. Abnormalities in gas exchange during exercise reflect the pathophysiology of early pulmonary vasculopathy by a mismatch of pulmonary blood flow to ventilation, and a reduced oxygen transport capacity. Cardiopulmonary exercise testing (CPET) is a quantitative and specific way of measuring ventilation-/perfusion relationships and oxygen transport capacity during exercise.
HYPOTHESIS We hypothesized that CPET could detect early gas exchange abnormalities suggestive of pulmonary vasculopathy in subjects at risk for PAH, and to assess the etiology for exercise intolerance in patients not suspected to have vasculopathy.
METHODS We prospectively recruited 18 consecutive patients with scleroderma from Harbor-UCLA rheumatology clinic who had not been previously diagnosed with PAH and were not suspected to have the disease. Each patient performed CPET. The physiological data were graphed in a standard 9-panel plot. High VE/VCO2 ratios (> 34) combined with a low PETCO2 (< 32 mmHg), both at the anaerobic threshold (AT), or a decrease in PETCO2 during exercise were considered to be suggestive of pulmonary vasculopathy.
RESULTS Exercise tolerance was reduced in 12 of the 18 patients. In 6 pts, evidence of pulmonary vasculopathy was present, and the other 6 had evidence of left-sided heart disease. Table 1⇓ shows the diagnoses elucidated by the CPET studies.
CONCLUSIONS CPET detected pulmonary vasculopathy in 6 of 18 cases, and differentiated the pathophysiology of exercise intolerance in scleroderma patients. Serial measurements are being performed to assess the rate of progression of early pulmonary vasculopathy in this patient cohort. Table 1⇓. Pathophysiology and type in the scleroderma population, revealed by CPET