Extension to CQTI571A2102 to Evaluate Long-term Safety, Tolerability and Efficacy of Imatinib in Severe Pulmonary Arterial Hypertension (PAH)

Inclusion Criteria: * Patients who completed in CQTI571A2102 clinical trial including all Study Completion assessments at the end of study visit met the eligibility criteria for that study and did not meet withdrawal criteria for safety reasons during study conduct Exclusion Criteria: * Patients with left ventricular ejection fraction (LVEF) \< 45% * Patients with thrombocytopenia, platelet count \< 50 x109/L (50 x 103/µL). * Patients with uncontrolled systemic arterial hypertension, systolic pressure \> 160 mmHg or diastolic pressure \> 90 mmHg. * Patients with a QTcF \> 450 ms for males and \> 470 ms for females in the absence of right bundle branch block. Other protocol-defined inclusion/exclusion criteria may apply