Verapamil for unstable angina at rest: a short-term randomized, double-blind study

To assess the efficacy of verapamil in individuals with unstable angina at rest, 11 patients (five men and six women, average age 55 years) with recurrent chest pain at rest and transient ST segment deviation (elevation or depression greater than or equal to 0.1 mV) on continuous ECG monitoring were enrolled in a 3-day double-blind, randomized study. The day before randomization (day 1), all received single-blind placebo. On day 2 they were randomized to placebo (n = 6) or verapamil, 320 mg per day (n = 5). On placebo, the number of chest pains (day 1, 2.8 +/- 2.1; day 2, 2.2 +/- 2.5; NS), nitroglycerin used (day 1, 2.7 +/- 4.4 tablets; day 2, 2.2 +/- 3.5 tablets; NS), and ST segment deviations (day 1, 8.5 +/- 5.9; day 2, 5.3 +/- 7.1; NS) did not change. On verapamil, the number of chest pains (day 1, 5.4 +/- 2.2; day 2, 1.6 +/- 2.1; p less than 0.01), nitroglycerin used (day 1, 5.0 +/- 4.5 tablets; day 2, 1.6 +/- 2.6 tablets; p = 0.057), and ST segment deviations (day 1, 12.6 +/- 4.7; day 2, 6.2 +/- 6.2; p less than 0.05) fell. Since five of six placebo patients had frequent chest pain and ST segment deviations on day 2, they were changed blindly to verapamil, 320 mg per day. Of the five verapamil patients, three had no chest pain or ST segment deviations on day 2, but two had continued chest pain and ST segment deviations and were increased blindly to 480 mg verapamil per day. Of the eight patients given verapamil (320 mg per day) on day 3, five had chest pain or ST segment deviations and were increased blindly to 480 mg verapamil per day on day 4. Of the seven who received 480 mg verapamil per day on day 4, three had chest pain and ST segment deviations similar in frequency to that occurring on day 1. Thus in patients with unstable angina at rest, verapamil exerts an initial beneficial effect, but in some individuals this salutary influence is not sustained.