Efficacy of slow-release nifedipine on ischemic attacks in patients with variant angina

We examined the effects of slow-release nifedipine on ischemic attacks in eight patients with variant angina. The study period was divided into four parts: placebo I period; nifedipine I period, when 20-mg slow-release nifedipine was given once a day at 10:00 p.m.; placebo II period; and nifedipine II period, when 20-mg slow-release nifedipine was given twice a day at 10:00 p.m. and 6:00 a.m. Each period consisted of 4 days, and 48-hour Holter monitoring was done at the end of each period. There was a significant decrease in the number of the episodes per 48 hours during the nifedipine I and nifedipine II periods as compared with the placebo I period (2.4 +/- 2.2 vs. 25.7 +/- 12.3, p less than 0.01; and 0.1 +/- 0.1 vs. 25.7 +/- 12.3, p less than 0.01, respectively). The total duration of episodes of ST-segment elevation per 48 hours decreased significantly during the nifedipine I period and the nifedipine II period as compared with the placebo I period (2.4 +/- 2.2 vs. 87.6 +/- 30.2 minutes, p less than 0.01; and 0.3 +/- 0.3 vs. 87.6 +/- 30.2 minutes, p less than 0.01, respectively). The total duration of the episodes also decreased significantly during the nifedipine II period as compared with the placebo II period (0.3 +/- 0.3 vs. 31.6 +/- 20.1 minutes, p less than 0.05). We concluded that 20-mg slow-release nifedipine given once a day at 10:00 p.m., or twice a day at 10:00 p.m. and 6:00 a.m., is highly effective in suppressing ischemic episodes in patients with variant angina.