Platelet Function Monitoring Unhelpful for Elderly Stented Patients

By Marilynn Larkin

NEW YORK (Reuters Health) - Using platelet function monitoring to adjust antiplatelet therapy in elderly patients stented for acute coronary syndromes has no effect on outcomes, researchers based in France report.

Elderly patients are at high risk of ischemic and bleeding events, and platelet function monitoring might enable individualization of treatment to improve the therapeutic risk:benefit ratio. However, that improvement has not been shown in several previous studies, according to Dr. Gilles Montalescot, director of the cardiac care unit at Pitie-Salpetriere Hospital in Paris, and colleagues.

To assess the effect of platelet function monitoring for treatment adjustment, the team conducted a multicenter trial in patients 75 and older with ST-elevation or non-ST-elevation acute coronary syndrome who were treated with implantation of a bare-metal or drug-eluting stent.

As reported in The Lancet, online August 28, and published to coincide with presentations at the European Society of Cardiology Congress in Rome, they randomly assigned 442 patients to the monitoring group and 435 patients to the "conventional" group.

Patients in the monitoring group received 5 mg of oral prasugrel daily, with a dose or drug adjustment in case of inadequate response. Those in the conventional group received the same dose of medication, but with no monitoring or treatment adjustment.

Platelet function testing was done two weeks after randomization in both groups, and was repeated two weeks after any treatment adjustment for those in the monitoring group.

The primary endpoint of the study was a composite of cardiovascular death, heart attack, stroke, stent thrombosis, urgent revascularization, and bleeding complications after one year. That endpoint was reached in 28% of patients in the monitoring group and 28% of patients in the conventional group. In addition, rates of bleeding events did not differ significantly between groups.

Dr. Montalescot told Reuters Health by email, "This trial comes after a similar study published by the same . . . group . . ., which showed no benefit of platelet function testing and treatment modification in a lower-risk population of stable patients undergoing elective stenting."

"Measuring platelet function is a time-consuming and costly procedure and does not appear to benefit patients, even when they present with extremely high risk," he said. "It does not improve prognosis, regardless of the drug used and the risk profile of the patient . . . . It is time to face reality."

Dr. Dirk Sibbing of the German Center for Cardiovascular Research in Munich, coauthor of a related editorial, commented, "Surely, platelet function testing is valuable for predicting the outcome of PCI-treated patients. However, its value for guiding treatment of an individual warrants further investigation, and (this study), ANTARCTIC, is not the end here. (It) is a very well done and important trial but future studies will have to test distinct approaches."

"In invasively managed acute coronary syndrome patients, the ongoing TROPICAL-ACS trial follows a different rationale, with a stage-adapted treatment consisting of high-level platelet inhibition for all patients during the acute and sub-acute phase and a platelet function testing-guided de-escalation to clopidogrel as the default therapy during the chronic treatment course," he observed.

Dr. Sibbing concluded, "We have to seek new and innovative strategies to reduce bleeding risk in these patients and strategies that implement platelet function testing to de-escalate treatment could be helpful here. We still have a long way to go toward improving and optimizing antiplatelet treatment regimens in the elderly and beyond."

The study was funded by Eli Lilly, Daiichi Sankyo, Stentys, Accriva Diagnostics, Medtronic, and Fondation Coeur et Recherche. Dr. Montalescot and 14 coauthors reported receiving fees from industry. Dr. Sibbing also reported receiving fees from Eli Lilly, Daiichi Sankyo and other companies.

SOURCE: https://bit.ly/2crDUot

Lancet 2016.

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