Platelet function testing ‘not supported’ in stented elderly ACS patients
medwireNews: Elderly patients with acute coronary syndromes (ACS) do not benefit from platelet function guided P2Y12 antagonist adjustment following percutaneous coronary intervention, results of the French ANTARCTIC trial show.
Gilles Montalescot (Hôpital Pitié-Salpêtrière, Paris) and co-investigators say their study “does not support” platelet function testing in high-risk situations, even though international guidelines still recommend this practice.
The researchers randomly assigned 877 patients aged 75 years or older who had undergone coronary stenting for ACS to receive oral prasugrel 5 mg daily either with (monitoring group, n=442) or without (conventional group, n=435) dose or drug adjustment in case of inadequate response.
Platelet function testing at 14 days led to treatment adjustment in 45% of patients in the monitoring group: 39% had low on-treatment platelet reactivity and were switched to clopidogrel 75 mg/day, 4% had high platelet reactivity and switched to prasugrel 10 mg and 2% stopped P2Y12 antagonist treatment altogether.
Despite the proportion of monitored patients within the platelet inhibition target range (85–208 P2Y12 reaction units) increasing from 42% on day 14 to 66% on day 28, there was no significant difference between the two treatment groups in the primary composite endpoint of cardiovascular death, myocardial infarction, stroke, stent thrombosis, urgent revascularisation and Bleeding Academic Research Consortium-defined bleeding complications (types 2, 3 or 5).
During 12 months of follow-up, 28% of patients in each group experienced this endpoint.
There were also no differences between the monitoring and conventional treatment groups in the individual components of the primary endpoint or in the rates of major bleeding and minor bleeding, irrespective of the definition used.
“The present results along with those of the ARCTIC study strongly suggest that the failure to improve the prognosis of patients by monitoring and individualisation of antiplatelet therapy is related neither to the risk level of the population nor to the type of P2Y12 antagonist, as hypothesised after the results of the first randomised studies”, Montalescot and co-authors conclude in The Lancet.
In an accompanying comment, Dirk Sibbing and Steffen Massberg, both from Ludwig-Maximilians-Universität Mü̈nchen, Germany, say that because the ANTARCTIC default strategy of low-dose prasugrel offered no clinical benefit, future studies will need to test other approaches.
“Staged treatment de-escalation (with or without drug monitoring) in addition to individualised treatment approaches will be the focus of at least some of the ongoing trials”, they write.
“The hope is that future studies will further improve the outcome of patients with acute coronary syndrome, not just in elderly people, but in the entire patient population.”
By Laura Cowen
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