AMLODIPINE IN RESIDUAL STABLE EXERTIONAL ANGINA-PECTORIS AFTER CORONARY-ARTERY BYPASS-SURGERY - A RANDOMIZED, PLACEBO-CONTROLLED, DOUBLE-BLIND, CROSSOVER STUDY

Because of the long half-life (35 to 50 hours) of amlodipine, a calciu m antagonist belonging to the dihydropyridine group, once-daily admini stration has been proposed. The aim of this study was to compare the e ffects of amlodipine and placebo on symptoms and exercise tolerance in patients with residual exertional angina after myocardial revasculari sation. 16 patients (13 mates, 3 females; mean age 61.9 +/- 7.3 years) with chronic stable angina despite a previous myocardial revascularis ation (more than 3 attacks per week after at least 3 months of pharmac ological treatment) were enrolled. All patients had reproducible angin a and >1mm horizontal or down-sloping ST-segment depression during two consecutive maximal exercise tests at the end of 2 weeks of a single- blind placebo period. A double-blind crossover study followed, in whic h 2 weeks on placebo were alternated with 2 weeks on amlodipine 10mg/d ay. An exercise cycloergometric test was performed 24 hours after the end of each treatment period. Concomitant antianginal treatment, with the exception of nitroglycerin, was not allowed. After administration of amlodipine, patients showed a significant increase in pressure-rate product at ischaemic threshold (238 +/- 27 vs 212 +/- 29mm Hg . beats /min . 10(-2); p<0.01) and an increase at peak exercise in ischaemic t hreshold (446 +/- 84 vs 324 +/- 96 sec; p<0.01), anginal threshold (46 9 +/- 87 vs 394 +/- 93 sec; p<0.01) and total exercise duration (515 /- 82 vs 398 +/- 86 sec; p<0.01). Amlodipine also significantly increa sed total work to ischaemic threshold (2710 +/- 908 vs 1590 +/- 752 kp m; p<0.01), angina (2930 +/- 970 vs 2197 +/- 912 kpm; p<0.01) and peak exercise (3223 +/- 950 vs 2247 +/- 912 kpm; p<0.01). In conclusion, i n these patients once-daily administration of amlodipine significantly increased the total exercise time and ischaemic and anginal threshold s, even 24 hours after the end of treatment, showing a prolonged anti- ischaemic protective effect.