RANDOMIZED, DOUBLE-BLIND TRIAL OF INTRAVENOUS DILTIAZEM VERSUS GLYCERYL TRINITRATE FOR UNSTABLE ANGINA-PECTORIS

The effect of dihydropyridines in patients with unstable angina is dis couraging. To find out the effect of the non- dihydropyridine-like cal cium-channel blocker diltiazem, a randomised, double-blind trial was c onducted comparing diltiazem with glyceryl trinitrate. both given intr avenously, in 129 patients with unstable angina. The endpoints were re fractory angina or myocardial infarction, individually and as a compos ite endpoint. Refractory angina alone or together with myocardial infa rction occurred significantly less commonly in the diltiazem group. Wh ile patients were on the trial drugs the numbers with refractory angin a were 6 (10%) in the diltiazem group versus 17 (28%) in the glyceryl trinitrate group (relative risk 0 . 36, p=0 . 02), and the numbers wit h refractory angina and myocardial infarction were 9 (15%) versus 23 ( 38%) (relative risk 0 . 40, p=0 . 007). Over 48 h the numbers were: re fractory angina 8 (13%) versus 18 (30%), relative risk 0 . 45, p=0 . 0 3, and refractory angina and myocardial infarction 12 (20 . 0%) versus 25 (41%), relative risk 0 . 49, p=0 . 02. Patients in the diltiazem g roup had better (p<0 . 05) event-free survival while taking the drugs. Heart-rate pressure product was reduced significantly only by diltiaz em (p<0 . 05). The incidence of bradyarrhythmias did not differ signif icantly. Atrioventricular conduction disturbances occurred in 5 (8%) p atients in the diltiazem group but were not seen in the glyceryl trini trate group (p=0 . 03). These disturbances could be reversed by decrea sing the dose of the drug or withdrawing it. No temporary pacemakers w ere required. Headache requiring an analgesic or dose adjustment occur red significantly less in the diltiazem group: 3 (5%) versus 15 (25%), relative risk 0 . 20 (p<0 . 004). These results indicate that intrave nous diltiazem, compared with intravenous glyceryl trinitrate, signifi cantly reduces ischaemic events and can be used safely in patients wit h unstable angina.