To the Editor: We are concerned that the recent studies on enoxaparin vs unfractionated heparin leave the duration of heparin treatment ill-defined for patients with acute coronary syndromes.
In the SYNERGY trial,1 duration of drug administration was left to the judgment of the treating physician. SYNERGY was an open-label trial, and subcutaneous enoxaparin is more convenient than intravenous unfractionated heparin, which could lead to longer treatment. Therefore, it is possible that differences between enoxaparin and unfractionated heparin may be biased by longer treatment with 1 study drug. SYNERGY did not present actual duration of treatment.
Similarly, the A to Z trial2 did not present its definition of treatment duration. The median time that patients received study drug was similar for both drugs: 49 hours for enoxaparin vs 48 hours for unfractionated heparin. However, time receiving enoxaparin varied much more than time receiving unfractionated heparin, as judged by the 25th and 75th percentiles.
Two previous studies only loosely defined duration of heparin treatment. In the ESSENCE trial,3 both heparins could be given for 48 hours to 8 days. ESSENCE did not indicate whether treatment duration differed between enoxaparin and unfractionated heparin. In TIMI 11B,4 median time receiving enoxaparin was 4.6 days but only 3.0 days for unfractionated heparin. Accordingly, the accompanying systematic overview5 had little comment on treatment duration.
Duration of high-dose heparin treatment may be especially relevant for bleeding rates, which were higher with enoxaparin in all studies.1 - 4 Optimal duration of antithrombin treatment remains poorly defined in acute coronary syndromes and awaits appropriate testing.
Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature
Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal
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