CLINICAL PROMISE OF CALCIUM-ANTAGONISTS IN THE ANGIOPLASTY PATIENT

Depending upon the definition used, restenosis occurs in 10-60% of pat ients who undergo percutaneous transluminal coronary angioplasty. Rest enosis appears to be the result of a combination of pathophysiological processes, including elastic recoil of arterial walls, platelet depos ition and thrombus formation and resultant fibro-cellular neointimal h yperplasia. A range of pharmacological interventions has been used in an attempt to reduce the rate of restenosis following angioplasty, wit h little success. Furthermore, many patients who undergo angioplasty s till suffer from ischaemia after the procedure. Calcium antagonists, s uch as the long-acting dihydropyridine amlodipine, have been demonstra ted to be effective in the control of both symptomatic and asymptomati c ischaemia and are, therefore, likely to be of utility for this purpo se in angioplasty patients. Calcium antagonists also exhibit character istics that may lead to a reduction in restenosis, in that they inhibi t platelet aggregation, reduce vasopasm and inhibit the action of mito gens which stimulate proliferation and migration of smooth muscle cell s. The results of five trials of calcium antagonists in angioplasty pa tients have been individually unconvincing in terms of prevention of r estenosis, only one trial demonstrated a significant effect. However, a meta-analysis of these results has demonstrated an approximately 30% reduction in the chance of restenosis in those patients treated with calcium antagonists. The Coronary Angioplasty Amlodipine in Restenosis (CAPARES) trial has been initiated to assess the impact of amlodipine upon the rare of restenosis and angina/ischaemia after the procedure.