This is a Phase II randomized, double-blind, placebo-controlled trial of sildenafil in men and women with Scleroderma with mildly elevated pulmonary pressures (SSc-MEP) to determine whether sildenafil may be an effective treatment for SSc-MEP.

Data shows that sildenafil (SIL) is an effective therapy in SSc-PAH. SIL has been safely used in many patients with various vascular and cardiovascular diseases over the past three decades. Randomized controlled trial data for SIL shows improvement in 6MWD, hemodynamics, and even evidence of cardiac remodeling in PAH and SSc-PAH patients. Based upon these data, SIL may be an effective therapy in SSc-MEP. This study will help determine whether sildenafil could be a good treatment for patients with scleroderma that have mildly elevated pulmonary pressures.

Inclusion Criteria:

• Previous documentation of mean pulmonary artery pressure between 21 and 24 mm Hg with a pulmonary capillary wedge pressure (or left ventricular end-diastolic pressure) ≤ 15 mm Hg within six months before study entry.
• Diagnosis of SSc according to 2013 American College of Rheumatology/ European League Against Rheumatism (ACR/EULAR) classification criteria.
• Pulmonary function tests with forced expiratory volume in one second/forced vital capacity (FEV1/FVC) >50% AND either a) total lung capacity (TLC) or forced vital capacity (FVC) > 70% predicted or b) TLC or FVC between 60% and 70% predicted with no more than mild interstitial lung disease on computerized tomography scan of the chest on studies obtained within 6 months of enrollment.
• Ventilation perfusion scan or computed tomography with intravenous contrast (CT angiogram) without evidence of chronic thromboembolism at anytime before study entry.
• Ability to perform six minute walk testing without significant limitations in musculoskeletal function or coordination.
• Informed consent.

Exclusion Criteria:

• World Health Organization (WHO) Class IV functional status.
• Systolic blood pressure less than 90 mmHg at screening visit prior to enrollment.
• Clinically significant untreated sleep apnea.
• Left-sided valvular disease (more than moderate mitral valve stenosis or insufficiency or aortic stenosis or insufficiency), pulmonary artery or valve stenosis, or ejection fraction < 45% on most recent echocardiography (within 1 year).
• Use of Pulmonary Arterial Hypertension (PAH) therapy (prostacyclin analogues, endothelin-1 receptor antagonists,phosphodiesterase-5 inhibitors, riociguat, selexipag) within the past 3 months.
• Hospitalized or acutely ill.
• Renal failure (creatinine above 2.0) at screening visit.
• Enrollment in a clinical trial or concurrent use of another investigational drug (non FDA approved) or device therapy within 30 days of screening visit.
• Age < 18.
• Currently pregnant.
• Current use of nitrates.