Borderline Pulmonary Arterial Pressure Is Associated with Decreased Exercise Capacity in Scleroderma

Rationale: Pulmonary arterial hypertension is associated with impaired exercise capacity and decreased survival in patients with scleroderma. Randomized controlled studies showed significant benefit of targeted therapies in patients with a resting mean pulmonary arterial pressure (MPAP) greater than 25 mm Hg. The clinical relevance of pulmonary arterial pressure values in the upper normal range is unknown. Objectives: To examine the clinical relevance of pulmonary arterial pressure in scleroderma patients. Methods: After a noninvasive screening program, 29 patients with systemic sclerosis without significant lung fibrosis and without known pulmonary arterial hypertension underwent right heart catheterization and simultaneous cardiopulmonary exercise test. A six-minute walk distance (6MWD) was determined within 48 hours. Measurements and Main Results: A resting MPAP above the median (17 mm Hg) was associated with decreased 6MWD (396 +/- 71 vs. 488 +/- 76 m; P < 0.005) and peak Vo(2) (76 +/- 11% vs. 90 +/- 24%; P = 0.05). Resting pulmonary vascular resistance was inversely correlated with 6MWD (r = 0.45; P < 0.05). At 25 and SOW, MPAP above the median (23 and 28 mm Hg) was associated with decreased 6MWID (P < 0.005; P < 0.0005). At peak exercise, MPAP showed no association with 6MWD or peak Vo(2); however, cardiac index was positively (r = 0.45; P < 0.05) and pulmonary vascular resistance was negatively correlated with 6MWD (r = -0.38; P < 0.05). Conclusions: MPAP and resistance in the upper normal range at rest and moderate exercise are associated with decreased exercise capacity and may indicate early pulmonary vasculopathy in patients with systemic sclerosis. Investigations on the prognostic and therapeutic implications of such borderline findings are warranted. Clinical trial registered with http://www.clinicaltrials.gov (NCT00609349).