The treatment phase will consist of two parts: an efficacy evaluation period, with a 2 week titration period (from randomization to week 2, visit T1 to visit T3) up to 12 weeks, followed by a long-term safety evaluation period until the end of week 52. Antihypertensive treatment such as diuretics, beta blockers or calcium channel blockers can be introduced or re-introduced if indicated during the long term safety evaluation period but angiotensin converting enzyme inhibitors (ACE-I) or angiotensin receptor blockers (ARBs) are not permitted.