Safety and Efficacy Study of HGP1207 in Patients With Pulmonary Hypertension

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