EFFECT OF AMLODIPINE, ATENOLOL AND THEIR COMBINATION ON MYOCARDIAL-ISCHEMIA DURING TREADMILL EXERCISE AND AMBULATORY MONITORING

Objectives. This study compared the effects of amlodipine, atenolol an d their combination on ischemia during treadmill testing and 48-h ambu latory monitoring. Background. It is not known whether anti-ischemic d rugs exert similar effects on ischemia during ambulatory monitoring an d exercise treadmill testing. Methods. Patients with stable coronary a rtery disease and ischemia during treadmill testing and ambulatory mon itoring were randomized to receive amlodipine (n = 51) or atenolol (n = 49). Each group underwent a counterbalanced, crossover evaluation of single drug and placebo, followed by evaluation of the combination. R esults. Amlodipine and the combination prolonged exercise time to 0.1- mV ST segment depression by 29% and 34%, respectively (p < 0.001) vers us 3% for atenolol (p = NS). During ambulatory monitoring, the frequen cy of ischemic episodes decreased by 28% with amlodipine (p = 0.083 [N S]), by 57% with atenolol (p < 0.001) and by 72% with the combination (p < 0.05 vs. both single drugs; p < 0.001 vs. placebo). Suppression o f ischemia during exercise testing and ambulatory monitoring was simil ar in patients with and without exercise induced angina. Exercise time to angina improved by 29% with amlodipine (p < 0.01), by 16% with ate nolol (p < 0.05) and by 39% with the combination (p < 0.005 vs. placeb o, atenolol and amlodipine). In patients with angina, total exercise t ime improved by 16% with amlodipine (p < 0.001), by 4% with atenolol ( p = NS) and by 19% with the combination (p < 0.05 vs. placebo and eith er single drug). In those patients without angina, no therapy signific antly improved total exercise time. Conclusions. Ischemia during tread mill testing was more effectively suppressed by amlodipine, whereas is chemia during ambulatory monitoring was more effectively suppressed by atenolol. The combination was more effective than either single drug in both settings.