ATOLL: Enoxaparin in PCI for STEMI yields improved ischemic outcomes

Montalescot G. Session 707007-707008.

European Society of Cardiology Congress 2010

Patients undergoing primary percutaneous coronary intervention for STEMI derived a greater net benefit on ischemic outcomes when taking enoxaparin vs. unfractionated heparin, new results from a study suggested.

Researchers for the international ATOLL study enrolled 910 patients with STEMI undergoing primary PCI. Patients were randomly assigned to receive either 0.5 mg/kg enoxaparin (n=450) or unfractionated heparin (50-70 IU/kg with glycoprotein IIb/IIIa inhibitors and 70-100 IU/kg without GPIIb/IIIa inhibitors; n=460). The primary study endpoint was a composite of death, complications from MI, procedural failure or non-CABG major bleeding at 30 days. Secondary endpoints included an ischemic composite endpoint of death, recurrent MI/acute coronary syndromes or urgent revascularization at 30 days.

The study results indicated a relative rate of reduction of 17% between the two study groups favoring those assigned enoxaparin (33.7% vs. 28%, P=.07). The researchers also reported a 41% reduction in the rate for the combined secondary endpoint at 30 days favoring patients assigned unfractionated heparin (UFH) vs. enoxaparin (11.3% vs. 6.7%; log-rank test, P=.01). Patients taking UFH also had higher rates of death or complications from MI vs. those taking enoxaparin (12.4% vs. 7.8%; log-rank test, P=.02). The primary safety endpoint occurred in 4.9% of patients taking enoxaparin vs. 4.5% of patients taking UFH, which translated into a net clinical benefit (relative risk reduction, 32%; P=.03) in the combined endpoint of a reduction in death, complications from MI or major bleeding in patients taking enoxaparin vs. those taking UFH.

“We have performed the first pure head-to-head comparison between two anticoagulants in primary PCI, with all antiplatelet agents being even,” Gilles Montalescot, MD, a professor of cardiology and head of the intensive cardiology care unit at Hôpital la Pitié-Salpétrière in Paris, said in a press release. “In this comparison, intravenous enoxaparin did not reduce procedural failure, in particular, low TIMI flow and non ST-resolution, which had a direct impact on the primary endpoint. However, harder ischemic endpoints were all reduced with intravenous enoxaparin on top of intense antiplatelet therapy.”

The ATOLL investigators have performed an excellent trial on a background of high use of evidence-based therapies. The role of IIb/IIIa antagonists in the setting of intensive oral antiplatelet therapy is not well defined. The ATOLL investigators have shown that enoxaparin is safe and likely has a clinically relevant effect on ischemic endpoints for patients undergoing primary PCI. They have moved us close to the goal of further improving the outcomes of patients suffering STEMI.

– Harvey White, MD

Green Lane Cardiovascular Service

Cardiovascular Research Unit, Auckland City Hospital

Auckland, New Zealand

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