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Background: Low-molecular weight heparins have different pharmacokinetic and pharmacodynamic characteristics and may vary in efficacy. We compared the efficacy of enoxaparin with that of tinzaparin in the management of non-ST-segment elevation acute coronary syndromes (NSTACS).
Methods: A total of 438 patients with NSTACS were randomized to receive subcutaneous treatment with enoxaparin, 100 IU/kg twice daily (equivalent to 1 mg/kg twice daily; n = 220), or tinzaparin, 175 IU/kg once daily, (n = 218) for as long as 7 days. The primary composite end point was recurrent angina, myocardial infarction (or reinfarction), or death at day 7. Secondary end points were the primary end point at day 30 and the occurrence of individual events at days 7 and 30.
Results: The incidence of the primary end point was 12.3% in the enoxaparin group and 21.1% in the tinzaparin group (P = .015). At day 7, the rate of recurrent angina was lower with enoxaparin than with tinzaparin (11.8% vs 19.3%). At day 30, the incidences of the composite end point, recurrent angina, and myocardial infarction were also lower with enoxaparin, 17.7% vs 28.0% (P = .012), 17.3% vs 26.1% and 0.5% vs 2.8%, respectively. The rate of revascularization was lower in the enoxaparin group, 8.6% vs 17.9% (P = .010) at day 7 and 16.4% vs 26.1% (P = .019) at day 30. Rates of bleeding complications were similar in the 2 treatment groups.
Conclusions: This study indicates a benefit of enoxaparin (100 IU/kg twice daily) as compared with tinzaparin (175 IU/kg once daily) in the treatment of patients with NSTACS, which is sustained for at least 30 days.
Low-molecular weight heparins (LMWHs) are an alternative form of antithrombotic therapy with potential advantages as compared wit unfractionated heparin (UFH). Several clinical trials have evaluated different LMWHs, such as enoxaparin, nadroparin, dalteparin, tinzaparin, and reviparin, in the management of venous thrombosis and pulmonary embolism, indicating that LMWHs are at least as effective as UFH in this indication. Experience of the effects of LMWHs in patients with acute coronary syndromes without persistent ST-segment elevation is mainly based on randomized clinical trials evaluating enoxaparin, nadroparin, and dalteparin. There is only limited experience on the use of tinzaparin in patients with unstable angina. Clinical trials have shown that LMWHs are more effective than placebo and are at least as effective as UFH in patients with non-ST-segment elevation acute coronary syndromes (NSTACS). However, the results also raised the suspicion that different LMWHs are not equally effective in the treatment of patients with NSTACS.
LMWHs differ from each other in several characteristics, including molecular weight, anti-factor Xa:anti-factor IIa activity ratio, and biological properties. Variations in the safety and efficacy of different LMWHs that have been observed in clinical trials may reflect differences in either the molecular composition and pharmacologic properties or the study design and patient characteristics. Such issues are best resolved with head-to-head comparisons. The aim of the Enoxaparin Versus Tinzaparin in Non-ST-segment Elevation Acute Coronary Syndromes (EVET) study was to compare the efficacy of enoxaparin with that of tinzaparin in patients with NSTACS.
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