Amlodipine in Residual Stable Exertional Angina Pectoris after Coronary Artery Bypass Surgery

Abstract

Because of the long half-life (35 to 50 hours) of amlodipine, a calcium antagonist belonging to the dihydropyridine group, once-daily administration has been proposed. The aim of this study was to compare the effects of amlodipine and placebo on symptoms and exercise tolerance in patients with residual exertional angina after myocardial revascularisation. 16 patients (13 males, 3 females; mean age 61.9 ± 7.3 years) with chronic stable angina despite a previous myocardial revascularisation (more than 3 attacks per week after at least 3 months of pharmacological treatment) were enrolled. All patients had reproducible angina 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 which 2 weeks on placebo were alternated with 2 weeks on amlodipine 10mg/day. 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 pressurerate 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 threshold (446 ± 84 vs 324 ± 96 sec; p<0.01), anginal threshold (469 ± 87 vs 394 ± 93 sec; p<0.01) and total exercise duration (515 ± 82 vs 398 ± 86 sec; p<0.01). Amlodipine also significantly increased total work to ischaemic threshold (2710 ± 908 vs 1590 ±752 kpm; 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, in these patients once-daily administration of amlodipine significantly increased the total exercise time and ischaemic and anginal thresholds, even 24 hours after the end of treatment, showing a prolonged anti-ischaemic protective effect.