Transient myocardial ischemia after abrupt withdrawal of antianginal therapy in chronic stable angina.

In 47 patients with chronic stable angina and proven coronary artery disease, abrupt withdrawal of beta-adrenoceptor blocking agents either as monotherapy or in combination with calcium antagonists (group 1, n = 25) was compared with abrupt withdrawal of calcium antagonist monotherapy (group 2, n = 22) as regards the occurrence of cardiac events and total ischemic activity detected by ambulatory monitoring. Reinstitution of medical therapy was required in 6 patients (4 in group 1 and 2 in group 2). Ambulatory monitoring was initiated for 36 hours on 3 occasions: before withdrawal, and again 2 and 5 days after withdrawal. The first 2 monitorings were performed in the hospital and the last during daily activity. In group 1, the frequency of total ischemia increased by 64 and 148% from monitoring occasions 1 to 2 and 1 to 3, respectively (p less than 0.01), and silent ischemia increased by 100 and 129%, respectively (p less than 0.01). However, no significant change in transient myocardial ischemia was noted in group 2. Heart rate at onset of ischemia increased significantly in group 1 (p less than 0.01), in contrast to group 2 which had significant increases only in out-of-hospital values (p less than 0.05). These results indicate that a rebound increase in ischemic activity (mainly silent) occurs after abrupt withdrawal of beta-receptor blockade in patients with chronic stable angina. This increase in ischemic activity may be caused by increased myocardial oxygen demand.