Background: Recent data show that there is an unexpectedly high prevalence of 'inappropriate' pulmonary responses to exercise among patients with systemic sclerosis (SS). However, no consensus exists as to which threshold of pulmonary artery systolic pressure (PASP) can be considered diagnostically relevant.
Aim: To evaluate pulmonary vascular reserve and right ventricular function changes induced by exercise in SS patients without overt pulmonary arterial hypertension.
Methods and results: The study enrolled 172 consecutive SS patients in NYHA class I-II, with a peak tricuspid regurgitant jet velocity at echocardiography not greater than 3 m/s, and 88 control subjects. Echocardiography was performed at rest and at the end of a maximal exercise test. SS patients showed a higher exercise-induced PASP than control subjects (36.9±8.7 vs 25.9±3.3 mm Hg, p=0.00008). The response to effort was higher in the presence of moderate interstitial lung disease (39.7±9.3 vs 36.0±8.4 mm Hg, p=0.016) or subclinical left ventricular diastolic dysfunction (42.3±5.8 vs 37.0±8.6 mm Hg, p=0.015). In control subjects, PASP values were normally distributed at rest and after exercise. In SS patients, the distribution was normal at rest but bimodal after exercise, with a second peak at 52.2 mm Hg including 13% of the total SS population. Patients in this subgroup showed subtle abnormalities of right ventricular function at rest and, most importantly, a blunted increase in right ventricular systolic function with exercise.
Conclusion: Exercise echocardiography may identify a subset of SS patients with an inappropriate exercise-induced increase in PASP and early signs of right ventricular dysfunction.