The purpose of this study is to investigate the safety and clinical efficacy of HGP1207 (Sildenafil) in subjects with pulmonary hypertension associated with systolic heart failure.

Inclusion Criteria:

• Patients with a diagnosis of chronic heart failure (NYHA Class II and III)
• LVEF ≤ 40%
• Elevated systolic PAP: ≥ 40 mmHg
• Patients must be treated with an ACE inhibitor, ARB, beta-blocker, aldosterone antagonist at a stable dose for at least 4 weeks prior to visit 1

Exclusion Criteria:

• Patients with pulmonary hypertension associated with chronic obstructive pulmonary disease, interstitial lung disease, chronic thromboembolism or unclear/multifactorial mechanisms
• Patients who have received Nitrates/NO donor or Cytochrome P450 3A4 inhibitors within 30 days prior to visit 1
• Patients who have received calcium channel blocker, endothelin receptor antagonist, prostacyclin analogues, phosphodiesterase 5 inhibitors within 90 days prior to visit 1
• History of hypersensitivity or allergy to sildenafil or any excipients of its formulation
• Patients with hypertension (sitSBP >170 mmHg or sitDBP>100 mmHg) or hypotension (sitSBP<90 mmHg or sitDBP<50 mmHg)
• Patients with other medical condition (i.e.,alcoholism, drug abuse) that may cause the patient to be non-compliant with the protocol, confound the data interpretation
• Pregnant females or those of child bearing potential who have not had a negative pregnancy test