If any subjects develops SiBPs > 139/90 mmHg, open label amlodipine will be give to maintain SiBP < 139/90 mmHg, attempting however to reach the goal of SiSBP < 120 mmHg. Amlodipine will be started at a dose of 2.5mg daily and up-titrated every 4 weeks to 5 mg daily and then to 10 mg daily. As long as SiBP < 139/90 mmHg, subjects will not be discontinued from the study. Subjects whose hypertension is not adequately controlled (SiBP > 139/90 mmHg) with addition of amlodipine up-titrated to 10 mg daily, however, will be discontinued from the study.