Photo courtesy of NIH
ROME—Results of the ANTARCTIC trial suggest that monitoring platelet function to individualize antiplatelet therapy does not improve outcomes for elderly patients stented for an acute coronary syndrome.
These patients had a high risk of ischemic and bleeding complications, but the study showed no significant difference in the incidence of such complications between patients who were monitored and those who were not.
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,” said study investigator Gilles Montalescot, MD, PhD, of Hôpital Pitié-Salpêtrière in Paris, France.
“Our study does not support this practice and these recommendations. 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 like those enrolled in ANTARCTIC.”
Results of the ANTARCTIC trial were presented at ESC Congress 2016 (abstract 2221) and published in The Lancet.
The study was funded by Eli Lilly and Company, Daiichi Sankyo, Stentys, Accriva Diagnostics, Medtronic, and Fondation Coeur et Recherche.
ANTARCTIC enrolled 877 patients, ages 75 and older, who presented with an acute coronary syndrome and underwent coronary stenting.
All patients were started on the antiplatelet agent prasugrel (5 mg), with 442 randomized to the conventional therapy (no adjustment) and 435 randomized to monitoring and treatment adjustment if needed.
Patients in the monitoring arm received 14 days of the daily 5 mg prasugrel dose, 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 endpoint of the trial was the composite of cardiovascular death, myocardial infarction, stroke, stent thrombosis, urgent revascularization, and bleeding complications at 1 year.
This endpoint occurred at a similar rate in both arms of the study—27.6% in the monitoring arm and 27.8% in the conventional therapy arm (hazard ratio=1.003; P=0.98).
Similarly, there was no significant difference between the arms with regard to the main secondary endpoint—a composite of cardiovascular death, myocardial infarction, stent thrombosis, and urgent revascularization.
This endpoint occurred in 9.9% of patients in the monitoring arm and 9.3% of patients in the conventional arm (hazard ratio=1.06; P=0.80).
“Platelet function monitoring led to a change of treatment in 44.8% of patients who were identified as being over- or under-treated, yet this strategy did not improve ischemic or safety outcomes,” Dr Montalescot noted.
“ANTARCTIC confirms the ARCTIC study in a different population with a different drug and has addressed the potential limitations of the ARCTIC study but finally reached the same conclusion. I expect there will be adjustments of guidelines and practice in light of this.”
