LOW-MOLECULAR-WEIGHT HEPARIN VERSUS REGULAR HEPARIN OR ASPIRIN IN THETREATMENT OF UNSTABLE ANGINA AND SILENT ISCHEMIA

Objectives. This study was designed to test the hypothesis that low mo lecular weight heparin may lessen the severity of ischemic events in p atients with unstable angina. Background. Unstable angina is a thrombo tic process that requires intensive medical treatment. Although curren t treatment can reduce the number of complications, serious bleeding c ontinues to occur. Nadroparin calcium, a low molecular weight heparin, seems to be a safe therapeutic agent that does not require laboratory monitoring. Methods. A total of 219 patients with unstable angina ent ered the study at a mean time of 6.17 h after the last episode of rest pain. Patients were randomized to receive aspirin (200 mg/day [group A]), aspirin plus regular heparin (400 IU/kg body weight per day intra venously and titered by activated partial thromboplastin time [group B ]) and aspirin plus low molecular weight heparin (214 UIC/kg anti-Xa t wice daily subcutaneously [group C]). The major end points determined for the in hospital period were 1) recurrent angina, 2) myocardial inf arction, 3) urgent revascularization, 4) major bleeding, and 5) death. Minor end points were 1) silent myocardial ischemia, and 2) minor ble eding. Event rates were tested by chi-square analysis. Results. Recurr ent angina occurred in 37%, 44% and 21% of patients in groups A, B and C, respectively, and was significantly less frequent in group C than in either group A (odds ratio 2.26, 95% confidence interval [CI] 1 to 5.18, p = 0.03) or group B (odds ratio 3.07, 95% CI 1.36 to 7.00, p = 0.002). Nonfatal myocardial infarction was present in seven patients i n group A, four in group B and none in group C (group B vs. A, p = 0.5 ; group C vs. A, p 0.01). Urgent revascularization was performed in ni ne patients in group A, seven in group B and one in group C (C vs. A, p = 0.01). Two episodes of major bleeding occurred in group B. Silent myocardial ischemia was present in 38%, 41% and 25% of patients in gro ups A, B and C, respectively, and was significantly less frequent in g roup C than group B (odds ratio 2.12, 95% CI 0.97 to 4.69, p = 0.04). Minor bleeding was detected in 10 patients in group B, 1 patient in gr oup C (B vs. C, p = 0.01) and no patient in group A (A vs. B, p = 0.00 3). Conclusions. In this study, treatment with aspirin plus a high dos e of low molecular weight heparin during the acute phase of unstable a ngina was significantly better than treatment with aspirin alone or as pirin plus regular heparin.