Exercise-induced pulmonary hypertension in scleroderma patients: a common finding but with elusive pathophysiology.

Background: The etiology of exercise-induced pulmonary hypertension (exPH) in systemic sclerosis (SSc) remains a complex task, as both left ventricle (LV) diastolic dysfunction and pulmonary vascular disease can contribute to its development. We determined the incidence of exPH in SSc and examined the association between pulmonary artery systolic pressure (PASP) and tissue Doppler-derived indexes of pulmonary capillary wedge pressure (PCWP).

Methods: Thirty-eight patients with SSc were studied, using a cycloergometer protocol; 10 were excluded due to resting PH or absence of tricuspid regurgitation (TR); TR and mitral E-wave velocities, LV outflow tract time-velocity integral and LV septal E'-wave were measured before and in peak exercise to calculate cardiac output (CO), PCWP and pulmonary vascular resistance (PVR).

Results: Mean age of diagnosis was 57.9 ± 8.9 years. At a mean workload of 64 ± 29 Watts, 48% of patients increased PASP ≥ 50 mmHg. PCWP, assessed by the E/e' ratio, did not change significantly during exercise (10.2 ± 3.1-10.0 ± 5.1; P = NS). Only 3 patients had elevations of the E/e' ratio ≥ 13 during exercise; 2 of them had an exercise PASP ≥ 50 mmHg, yielding a proportion of exPH due to elevated LV filling pressures of 2/11 (18%). Patients with exPH had lower DLCO and had more frequently the diffuse SSc.

Conclusion: The elevation of PASP during exercise in most patients of this cohort seems to be related to a reduced pulmonary vascular reserve, and not to an increase in PCWP. Further studies are warranted to determine the therapeutic, as well as prognostic implications of these findings.