Evaluation of a New Vasodilating β-Blocking Agent, Carvedilol, in Exertional Angina Using Holter Monitoring

Antianginal and antiischemic effects and clinical pharmacologic actions of carvedilol, a novel β-blocking agent with a vasodilator action, were determined by Holter electrocardiographic monitoring in 13 patients with exertional angina. The patients were observed for 1 week prior to entry into the study, followed by 1 to 2 weeks of treatment with carvedilol. During the observation period the patients received one placebo tablet daily, and during the treatment period one 20mg tablet of carvedilol daily. Before and after the treatment 24-hour Holter electrocardiographic tracings were obtained. The mean interval of Holter monitoring was 11.2±4.5 days for the observation and treatment periods, and the mean time of drug administration was 8: 25 a.m. (±30min). The Holter electrocardiographic tracings which were obtained twice in 9 patients during the observation period showed a high degree of reproducibility with respect to the frequency, magnitude and duration of ST-segment depression. The total frequency of ST depression per patient was 4.5±3.4 events/day pre-drug and 2.1±2.1 events/day post-drug. There was a significant reduction in total frequency of ST depression post-drug (p<0.01). The frequency of asymptomatic ST depression was similarly decreased post-drug (p<0.01), and the total magnitude and duration of ST depression were significantly improved post-drug (p<0.01 and p<0.05, respectively). These effects of carvedilol lasted for 24 hours after administration. Considering that the heart rate was not excessively reduced during the night, and nocturnal myocardial ischemic episodes were not exacerbated, the mode of action of this drug seems to be based on not only a β-blocking action but also on a vasodilator action. Carvedilol benefits exertional angina when used in a 20mg s.i.d. regimen.