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May 24/31, 2006

Low-Molecular-Weight Heparin vs Unfractionated Heparin in Acute Coronary Syndromes—Reply

Author Affiliations

Letters Section Editor: Robert M. Golub, MD, Senior Editor.

JAMA. 2006;295(20):2353-2354. doi:10.1001/jama.295.20.2353-b

In Reply: Dr Schreiber raises questions about the potential relationship of aPTT values and coronary events. In the patients randomized to receive unfractionated heparin in the SYNERGY trial, approximately 33% and 44% were “therapeutic” (aPTT, 50-70 seconds) within the first 6 through 12 and 13 through 24 hours of randomization, respectively. We have been evaluating the information available in patients randomized to the unfractionated heparin group who received either no prior antithrombin therapy or who had received unfractionated heparin prior to randomization (n = 2608). This is a “pure” unfractionated heparin group similar to those patients enrolled in the OASIS-2 trial,1 which studied 5058 patients with a non–ST-segment elevation acute coronary syndrome receiving intravenous unfractionated heparin. In contrast to OASIS-2, we did not find a relationship between aPTT values and recurrent ischemic events, defined as death, (re)infarction, stroke, or recurrent angina requiring coronary revascularization at 7 days. Similarly, after adjusting for other important baseline predictors (such as age, history of hypertension, current smoking, and renal function), we did not find a relationship between aPTT values and Thrombolysis in Myocardial Infarction (TIMI) major bleeding unrelated to coronary artery bypass graft surgery in the SYNERGY group treated with unfractionated heparin.