Antiplatelet strategies in acute coronary syndromes: design and methodology of an international collaborative network meta-analysis of randomized controlled trials.

INTRODUCTION: The optimal choice of oral P2Y12 receptor inhibitors has the potential to significantly influence outcomes. We seek to compare the safety and efficacy of the three most commonly used oral P2Y12 receptor inhibitors (clopidogrel, prasugrel, and ticagrelor) in acute coronary syndromes (ACS) via a comprehensive systematic review and network meta-analysis. EVIDENCE ACQUISITION: In line with the Preferred Reporting Items for Systematic Reviews (PRISMA) guidelines, we performed a comprehensive search for RCTs which compared cardiovascular and hemorrhagic outcomes after use of at least two of the distinct oral P2Y12 receptor inhibitors (i.e. clopidogrel, prasugrel, and ticagrelor). A search strategy has been designed to systematically search multiple databases, including MEDLINE with PubMed interface, The Cochrane Central Register of Controlled Trials, and Embase. In addition, key inclusion criteria will be trial size of at least 100 patients and at least 1 month of follow-up time. Several prespecified subgroups will be explored, including Asian patients, patients presenting with ST-elevation myocardial infarction, patients of advanced age, and others. EVIDENCE SYNTHESIS: Exploratory frequentist pairwise meta-analyses will be based primarily on a random-effects method, relying on relative risks (RR) for short-term outcomes and incidence rate ratios (IRR) for long-term outcomes. Inferential frequentist network meta-analysis will be based primarily on a random-effects method, relying on RR and IRR as specified above. Results will be reported as point summary of effect, 95% CI, and P values for effect, and graphically represented using forest plots. CONCLUSIONS: An international collaborative network meta-analysis has begun to comprehensively analyze the safety and efficacy of prasugrel, ticagrelor and clopidogrel, each on a background of aspirin, for management of patients with ACS. It is our hope that the rigor and breadth of the undertaking described herein will provide novel insights that will inform optimal patient care for patients with ACS treated conservatively, or undergoing revascularization.

Early discontinuation of prasugrel or clopidogrel in acute coronary syndromes: insights from the TRILOGY ACS trial.

BACKGROUND: In the Targeted Platelet Inhibition to Clarify the Optimal Strategy to Medically Manage Acute Coronary Syndromes (TRILOGY ACS) trial of patients with non-ST-segment elevation acute coronary syndrome managed medically without revascularization, treated with prasugrel versus clopidogrel for less than or equal to 30 months after index acute coronary syndrome, post-hoc analyses showed a divergence of treatment effect in favor of prasugrel after 12 months. Potential influential factors, including a potential late treatment effect after early study drug discontinuation in the intention-to-treat analysis, have not been explored. PATIENTS AND METHODS: We carried out an exploratory, post-hoc analysis of 1436 patients who received at least one dose of the study drug and discontinued the drug 7-365 days after randomization. Kaplan-Meier event rates were evaluated starting at the landmark timepoint of study discontinuation through 2 years of follow-up, and were compared between prasugrel and clopidogrel. RESULTS: The unadjusted rates of the primary composite endpoint of cardiovascular death, myocardial infarction, or stroke were 20.1 versus 24.4% in the prasugrel versus clopidogrel groups (log-rank P=0.069). Similar findings were observed for cardiovascular death (13.3 vs. 18.0%, log-rank P=0.022), and cardiovascular death or myocardial infarction (19.3 vs. 23.3%, log-rank P=0.042). In multivariable analyses, there were no significant differences in the adjusted risk of these outcomes between the prasugrel and clopidogrel groups. CONCLUSION: In this hypothesis-generating analysis, high rates of ischemic events were observed after study drug discontinuation, with a lower frequency of events among patients treated with prasugrel versus clopidogrel that did not persist after multivariable adjustment. This analysis highlights the complexities of ascertaining downstream effects of antithrombotic therapies after drug discontinuation.

Impact of chronic antiplatelet therapy before hospitalization on ischemic and bleeding events in invasively managed patients with acute coronary syndromes: the ACUITY trial.

AIMS: Presentation with an acute coronary syndrome (ACS) on chronic aspirin therapy is an independent predictor of adverse short-term outcomes. Whether this finding applies to chronic thienopyridine use, and with the contemporary invasive management of ACS, is unknown. METHODS AND RESULTS: In ACUITY, 13819 patients with moderate and high-risk ACS were studied; patients transferred from an outside hospital were excluded from the present analysis, given uncertain preadmission antiplatelet status. Endpoints included major adverse cardiovascular events (MACE: death, myocardial infarction, or unplanned revascularization), major bleeding, and net adverse clinical events (NACE). Among 11313 study patients, 31 % were naive for antiplatelet agent, 49% were receiving aspirin alone, and 20% were on dual antiplatelet therapy. Chronic antiplatelet users were older and had a higher risk profile. After adjusting for baseline differences, chronic antiplatelet therapy (single or dual) was not associated with an increased incidence of 30-day MACE, bleeding, or NACE. However, patients on chronic aspirin or dual antiplatelet therapy at presentation had significantly higher 1-year rates of MACE [odds ratio (95% confidence interval) = 1.17 (1.01­1.36), P = 0.03 and 1.29 (1.02­1.64), P = 0.03, respectively]. Patients presenting on dual antiplatelet therapy had significantly greater adjusted MACE at 1-year than those on aspirin alone [odds ratio (95% confidence interval) = 1.34 (1.15­1.56), P < 0.0001]. CONCLUSION: Contrary to earlier studies, prior antiplatelet therapy was not associated with an increased risk of adverse outcomes at 30 days in invasively managed patients. Such use did, however, independently predict 1-year ischemic MACE, with outcomes worse for patients presenting on chronic dual antiplatelet therapy compared with aspirin alone.