Extension to QTI571A2301 to Evaluate the Long-term Safety, Tolerability and Efficacy of Imatinib in Severe Pulmonary Arterial Hypertension (PAH)

Inclusion Criteria:

- Patients who participated in CQTI571A2301 clinical trial and completed the week 24
visit of the study protocol, including all Study Completion assessments

- Patients who withdrew from the CQTI571A2301 study prematurely for reasons not related
to study drug or not related to a safety issue but performed all Study Completion
assessments

Exclusion Criteria:

- Patients with a pulmonary capillary wedge pressure > 15 mmHg at time of Study
Completion assessments in core protocol CQTI571A2301. If pulmonary capillary wedge
pressure is not attainable, then a left atrial pressure measurement may be used in
its place.

- LVEF < 45%

- Patients with thrombocytopenia, platelet count < 50E9/L (50E3/µL)

- Patients with uncontrolled systemic arterial hypertension, systolic > 160 mmHg or
diastolic > 90 mmHg

- Patients with a QTcF > 450 ms for males and > 470 ms for females in the absence of
right branch bundle block (based on Visit 1 ECG if required to be performed)

Other protocol-defined inclusion/exclusion criteria may apply