All patients who fulfil the inclusion criteria and who are prepared to participate in the study will be randomly assigned at the first issue of the study medicament to one of the groups. The patient will receive either amlodipine 10 mg or placebo. Both medicaments will be given as a single daily dose in the form of tablets in the morning. The study medication will not be changed during the course of the study, insofar as no side-effects are observed. Patients who are already taking a calcium channel blocker, and in whom a withdrawal phase is possible according to the opinion of their physician, will first undergo a wash-out phase of 4 weeks before starting with the double-blind treatment. During the study, the administration of all other necessary medicaments for the patient, apart from the administration of calcium channel blockers, is permitted. A check will be carried out at intervals of 6 months to see whether an event has occurred. Each patient will be observed for a period of 30 months.