Assessment of the efficacy, optimal dosage, and safety of diltiazem in early treatment of unstable angina pectoris.

BACKGROUND

The anti-ischemic benefits of diltiazem are well recognized; however, there are fewer studies of the use of intravenous diltiazem for early treatment of unstable angina pectoris (UAP).

HYPOTHESIS: The present study prospectively evaluated the efficacy, optimal dosage, and safety of continuous intravenous diltiazem for initial management of UAP.

METHODS

In all, 102 patients with UAP were recruited in this multicenter trial. Diltiazem was administered as a continuous intravenous infusion with a fixed incremental dosage of 1,3, and 5 microg/kg/min, titrated according to the patients' symptoms of angina, and then was maintained for a further 48 h at the angina-free dose. Episodes of angina, hemodynamic stability, and complications were observed.

RESULTS

Angina was adequately controlled with continuous intravenous infusion of diltiazem in 64 patients (63%) at a dosage of 1 microg/kg/min, in 26 patients (25%) at dosage of 3 microg/kg/ min, and in 6 patients (6%) at dosage of 5 microg/kg/min, leading to a cumulative effective ratio of 94% in all patients. Additional anti-ischemic medications were required in six patients (6%) who had refractory angina. Bradyarrhythmias noted in only six patients (6%) were reversible after decreasing the dosage of diltiazem. No acute myocardial infarction or other severe side effects occurred.

CONCLUSION

Continuous intravenous infusion of diltiazem is well tolerated and relieves symptoms rapidly and effectively in up to 94% patients with UAP, with the majority (63%) treated at the low dosage of 1 microg/kg/min. Diltiazem can be used as a first-line anti-ischemic agent for early conservation treatment of UAP.