ANTARCTIC: Platelet Function Testing Fails to Improve Outcomes in Elderly, High-Risk Patients

Platelet function testing in elderly patients at very high risk of ischemic and bleeding complications did not improve outcomes compared to a standard, unmonitored approach, according to results from the ANTARCTIC Trial presented Aug. 28 during ESC Congress 2016 in Rome simultaneously published in The Lancet.

In the study 877 patients, aged 75 years or more, who presented with an acute coronary syndrome and underwent coronary stenting, were randomized to receive conventional therapy (no adjustment) or monitoring and treatment adjustment (if needed). All patients were started on prasugrel (5 mg daily); however, patients in the monitoring arm received 14 days of the 5 mg prasugrel dose, but then underwent a platelet function test at day 14, followed by medication adjustment if the test showed high or low platelet reactivity. Additional monitoring was performed at day 28 in patients who needed treatment adjustment.

The primary end point – the composite of cardiovascular death, myocardial infarction (MI), stroke, stent thrombosis, urgent revascularization and bleeding complication at one year – occurred at a similar rate in both arms of the study – 27.6 percent in the monitoring group, and 27.8 percent in the conventional group (P=0.98). Additionally, there was no significant difference in rates of the main secondary end point – a composite of cardiovascular death, MI, stent thrombosis or urgent revascularization – which occurred in 9.9 percent and 9.3 percent, respectively (P=0.80). Study investigators did note that platelet function monitoring led to a change of treatment in 44.8 percent of patients, however, the strategy did not improve ischemic or safety outcomes.

The findings challenge current international guidelines which recommend platelet function testing in high-risk patients. “Platelet function testing is still being used in many centers to measure the effect of antiplatelet drugs and adjust the choice of these drugs and their doses. Our study does not support this practice and these recommendations,” said senior investigator Gilles Montalescot, MD, PhD.

“Although measuring the effect of antiplatelet agents makes sense in order to choose the best drugs or doses, this costly and more complex strategy does not appear to benefit patients, even when they present with extremely high risk of ischemic and bleeding events liked those enrolled in ANTARCTIC,” he adds.

Keywords: ESC Congress, Acute Coronary Syndrome, Aged, Blood Coagulation Tests, Blood Platelets, Platelet Activation, Platelet Function Tests, Stents, Angiography

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