Systemic sclerosis (SSc) is a severe form of associated pulmonary arterial hypertension (PAH), for which annual screening is recommended based on resting echocardiography. While the latter may be normal in the early stages of PAH, exercise echocardiography (Ex-Echo) may provide additional insights on pulmonary vascular function. However, the clinical use of Ex-Echo is limited by methodological concerns. Although it is currently admitted that pulmonary arterial pressure (PAP) at exercise should be interpreted relative to flow change, few studies investigated the relationship between PAP and cardiac output (CO) during exercise in SSc patients.

We sought to explore exercise-induced changes in the pulmonary circulation by pressure-flow relationship in SSc patients compared with healthy subjects.

SSc patients without overt lung or heart involvement, and healthy subjects underwent symptom-limited Ex-Echo to generate multipoint relationship between meanPAP (PAPm) and CO. Conventional markers of RV function were also recorded during exercise.

Forty-two patients and 47controls were included. At peak exercise, patients had lower PAP, lower CO, but higher PAPm to CO ratio (TPR) than controls (Table 1). The slope of PAPm to CO relationship (P/Q slope) was higher in patients (Fig. 1), but this was not significant after correction for age. Age was an independent determinant for the P/Q slope, but did not affect the difference in peak-exercise TPR. Markers of RV function (TAPSE, S wave velocity, and IVA) were lower in patients at exercise.

SSc patients presented with different pulmonary vascular and myocardial adaptation to exercise compared with healthy individuals. In contrast with P/Q slope, changes in peak TPR were not influenced by age. This pattern may be observed in patients without evidence of cardiac or pulmonary involvement and explain, at least in part, lower exercise capacity in these patients.