Long-term extension, multi-centre, multi-national study to evaluate the safety and tolerability of oral BAY 63-2521 (1 mg, 1.5 mg, 2 mg, or 2.5 mg tid) in patients with symptomatic Pulmonary Arterial Hypertension (PAH).

Pulmonary Arterial Hypertension (PAH) is a severe disease with a high
mortality. Although several drugs have been approved for the treatment of PAH
in the recent past, there is still a high medical need for new treatments.

Although the experiences with BAY 63 2521 with respect to the treatment of PAH
are limited, in the light of the severity of the underlying disease it is
justified to offer all patients who participated in the PATENT-1 trial a
long-term treatment with BAY 63 2521 (until commercially available).

BAY 63 2521 is a stimulator of the soluble guanylate cyclase (sGC) and is
intended for the treatment of cardiovascular diseases, especially pulmonary
hypertension (PH).

To assess the long-term safety and tolerability of BAY 63 2521 in the treatment
of naive patients and patients pretreated with an Endothelin Receptor
Antagonist or a Prostacyclin Analogue with symptomatic Pulmonary Arterial
Hypertension (PAH).

Multicentre, multinational, open label one arm study in patients with
symptomatic PAH.

Patients from the Placebo Arm and from the BAY 63 2521 1.5 mg Dose Arm of
PATENT 1 trial will be up-titrated to maximum of 2.5 mg. Patients from the 2.5
mg BAY 63-2521 arm will maintain the same dose in the PATENT-2 trial.

The treatment period is set up as follow:
1. Treatment Phase
a. Titration phase: 8 weeks
b. Main-study phase: Duration until BAY 63-2521 receives official approval and
will be commercially available.
2. Safety follow up phase: 30 days

Incase patients participate until day 84 + the safety follow-up period:
7 hospital visits, 1 time hospitalisation for day and night, study medication
tid, possible side-effectd due to study medication, blood pressure (15x), heart
rate (15x), WHO functional class (4x), 6 MWD (4x), Borg CR10 Scale (4X), lab
blood sampling (4x), PK blood sampling (2x), ECG (6x), EQ-5D questionairre
(1x), LPH questionairre (1x).

From day 84, every 3 months the following procedured will be repeated:
Study medication tid, possible side-effects due to study medication, physical
examination, blood pressure, heart rate, blood gas analysis, WHO functional
class , 6 MWD, Borg CR10 Scale, lab blood sampling, PK blood sampling, ECG,
pregnancy test if appicable, EQ-5D questionairre, LPH questionairre.