Dr. Neal S Kleiman
The session (Controversies in antiplatelet therapy) consisted of two hearty but professional debates.
Prof JP Collet argued that while measurement of on-treatment platelet reactivity is a good marker of cardiovascular risk, and is not necessarily reproducible from test to test. Reports of benefits from guided strategies are based on small non-randomized studies. Larger randomized trials, despite their flaws, have not shown evidence of improvement in outcomes using a test-based strategy. He raised the possibility that a multi-test strategy may prove to be most useful and pointed out that a rigorous randomized trial known as ANTARCTIC will study a monitoring-based strategy in high risk PCI patients aged > 75 years. Prof M Valgimigli argued that platelet function testing for P2Y12 inhibitors helps stratify patients according to bleeding and ischemic risks. Multiple observational trials, he pointed out, have indicated that when point-of-care testing has been performed in a sufficiently large number of patients, those with high on treatment platelet reactivity are at risk for stent thrombosis while those with low values are at risk for bleeding, and that there most likely is an optimum window for platelet reactivity. Assessments of sensitivity and specificity, which have been cited as arguments against the use of platelet function testing are designed to assess diagnostic tests when compared against known outcomes and are not appropriate to use for tests that are designed to predict prognoses.He agreed with Prof Collet that randomized trials to date have been disappointing, but stated that the weaknesses of these trials, including low event rates, inadequate therapies for high on treatment reactivity, and inadequate correction for GP IIb-IIIa use outweighed their usefulness. He pointed out that the PRU-MATRIX trial will compare customized anti-platelet therapy selection with liberal selection in patients with high risk ACS who undergo PCI.
In the second debate Prof Jukema argued that the current standard for treatment after stent placement is a minimum of one year of dual antiplatelet therapy and that the studies indicating otherwise have lacked sufficient power to indicate a shorter duration. In addition, no study has proven conclusively that current generation stents are associated with lower thrombosis rates than earlier stents.Prof Kastrati argued that prolonged treatment with dual antiplatelet therapy is not necessary and may be harmful. He pointed out that most of current thinking is based on early experience with bare metal stents and is mostly confined to events occurring within the first six months of the implant procedure. Four randomized trials to date have shown no benefit for prolonged dual antiplatelet stent placement after implantation of current generation drug-eluting stents, and in meta-analysis, indicate that the risk of bleeding is increased.Current data for new generation stents, and possibly for “developing generation” stents with biodegradable polymers indicate that these stents are associated with significantly lower rates of stent thrombosis than sirolimus-eluting stents. He humorously stated that any operator who believes that more than 6 months of DAPT are needed after stent placement, should feel obligated to implant a first generation stent to justify the increased bleeding risk associated with a prolonged regimen.
Controversies in antiplatelet therapy
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