New Antiplatelet Agents and the Role of Platelet Function Testing in Acute Coronary Syndromes

• Published in: Clinical therapeutics 2013-08, Vol.35 (8), p.1064-1068
• Main Authors: Sinhal, Ajay R., MD, FRACP, Aylward, Philip E., BM, PhD, FRACP, FCANZ
• Format: Article
• Language: English
• Subjects: Acute Coronary Syndrome - drug therapy; Acute coronary syndromes; Adenosine - analogs & derivatives; Adenosine - therapeutic use; Adenosine Monophosphate - analogs & derivatives; Adenosine Monophosphate - therapeutic use; Blood clots; Blood platelets; Blood Platelets - drug effects; Drug dosages; Drug therapy; Drug Therapy, Combination; Heart attacks; Humans; Internal Medicine; Medical Education; Metabolism; Metabolites; Mortality; Patients; Piperazines - therapeutic use; Platelet Aggregation Inhibitors - therapeutic use; platelet function; Platelet Function Tests; platelet inhibitors; Prasugrel Hydrochloride; Studies; Thiophenes - therapeutic use; Ticlopidine - analogs & derivatives; Ticlopidine - therapeutic use; Treatment Outcome
• ISSN: 0149-2918; 1879-114X
• DOI: 10.1016/j.clinthera.2013.07.429

Abstract Background Dual antiplatelet therapy is a guideline mandated for patients with acute coronary syndromes (ACS). Despite its use, thrombotic events continue to occur both early and late. Platelet function testing has been used to define the in vitro effects of new antiplatelet agents, and it has been suggested that it be used to choose therapy. The role of platelet function testing, particularly with newer antiplatelet agents, remains unclear. Objective We review the rationale for platelet function testing and its application in monitoring patients on antiplatelet therapy. We also review recent clinical trials of newer antiplatelet agents. On the basis of this review, we reach conclusions on the current role of antiplatelet function testing in monitoring modern antiplatelet therapy and the role of the new antiplatelet agents in the treatment of ACS. Methods We reviewed recent publications on platelet function testing and clinical trials of newer antiplatelet therapies compared with clopidogrel. Results Platelet function testing is complex, but there is now a bedside test, VerifyNow. High platelet reactivity has been associated with worse cardiovascular outcomes in patients undergoing percutaneous coronary intervention. Recent clinical trials have not found any advantage in outcomes in patients who have their therapy adjusted by monitoring their platelet function. Newer agents, prasugrel, ticagrelor, and cangrelor, produce more rapid, complete, less variable effects on platelet function than clopidogrel. Prasugrel was found to improve outcomes compared with clopidogrel in patients with ACS undergoing percutaneous intervention. Ticagrelor is beneficial in all patients with ACS and reduces cardiovascular mortality compared with clopidogrel. Cangrelor improves outcomes in patients undergoing stenting. Recent studies to assess the role of platelet function monitoring of the effects of clopidogrel and modifying treatments have not been successful. Conclusion Recent clinical trials have indicated that newer antiplatelet agents have advantages over clopidogrel in the treatment of ACS. Platelet function testing gives us a guide to the timing, efficacy, and variability of therapy and can correlate with poor patient outcomes; however, the use of antiplatelet function testing to tailor therapy does not seem appropriate.