Faculty Bibliography

AIMS/OBJECTIVE:To correlate inhibition of platelet aggregation (IPA) with bleeding events assessed by TIMI, GUSTO, and BleedScore scales in a large cohort of patients with coronary artery disease (CAD) and ischaemic stroke (IS) treated with chronic low-dose aspirin plus clopidogrel. Data from recent trials and registries suggest a link between increased risk of bleeding and cardiovascular mortality. However, the potential association of bleeding risk and IPA is not established. It may play a critical role for the safety of more aggressive platelet inhibition or/and individual tailoring of antiplatelet strategies. METHODS AND RESULTS/RESULTS:Secondary post hoc analyses of 5 microM ADP-induced IPA and bleeding complications assessed by TIMI, GUSTO, and BleedScore scales in a combined data set consisting of patients with documented CAD (n = 246) and previous IS (n = 117). Demographic characteristics differ substantially depending on the underlying vascular disease; however, IPA and bleeding risks were similar between CAD and IS. All three bleeding scales adequately captured serious haemorrhagic events, where the TIMI scale was the most exclusive, whereas BleedScore was the most inclusive. Over half of all patients experienced superficial event(s), most commonly occurring during two to three distinct bleeding episodes. There was no correlation between IPA and duration of antiplatelet therapy. Inhibition of platelet aggregation >50% strongly correlates with minor (r(2) = 0.58, P < 0.001; c-statistic = 0.92), but not severe (r(2) = 0.11, P = 0.038; c-statistic = 0.57), bleeding events. CONCLUSION/CONCLUSIONS:Chronic oral combination antiplatelet regimens are associated with a very high (56.5-60.7%) prevalence of superficial bleeding episodes, which are grossly underestimated in trials and registries. The role of such frequent mild complications for the overall benefit of antiplatelet therapy is entirely unknown, as is their effect on compliance. Although IPA is well suited for defining the risk of minor complications, prediction of more severe bleeding events may be challenging.

BACKGROUND: Clinical trials of antithrombotic agents for the treatment of ACS routinely assess bleeding as a safety endpoint, but variation in bleeding definitions makes comparison of the relative safety of these agents difficult. METHODS: The ABC Multidisciplinary Working Group, an informal working group comprising clinical researchers and representatives from the US Food and Drug Administration, the National Institutes of Health, and the pharmaceutical industry, sought to develop a consensus approach to measuring the incidence and severity of bleeding complications during clinical trials of acute coronary syndromes (ACS). A meeting of the ABC was convened in April 2008 in Washington, DC, with the goal of developing a consensus approach to measuring the incidence and severity of hemorrhagic complications during clinical trials of ACS. Relevant literature on bleeding was reviewed through a series of short lectures and intensive group discussion. RESULTS: Using existing evidence on bleeding and outcomes as well as clinical judgment, criteria for the assessment of bleeding were developed through expert consensus. This consensus statement divides bleeding-related data elements into three categories: essential, recommended, and optional. CONCLUSIONS: The ABC Group recommendations for collection and reporting of bleeding complications provide a framework for consistency in the collection of information on hemorrhagic complications in trials of ACS. Widespread adoption of the statement recommendations will facilitate understanding of the mechanisms of adverse outcomes after bleeding and comparisons of the relative safety of antithrombotic agents, as well as the interpretation of safety results from future studies.

BACKGROUND:Currently recommended anticoagulant agents used in the setting of percutaneous coronary intervention (PCI) inhibit, with varying degrees of intensity, 2 critical targets (factor Xa and/or IIa) of the coagulation cascade, yet they carry significant limitations. M118-a novel, rationally engineered heparin-provides consistent anti-Xa and anti-IIa activity with a constant anti-Xa:anti-IIa ratio over time. M118 also combines the desired anticoagulant effects of unfractionated heparin with the beneficial attributes of low-molecular-weight heparin, and may represent the next generation of heparin therapy in patients diagnosed with acute coronary syndrome. STUDY DESIGN/METHODS:The EMINENCE trial is a prospective, randomized, open-label, multicenter phase 2 study that will evaluate the safety and feasibility of M118 as an anticoagulant versus unfractionated heparin in subjects with stable coronary artery disease undergoing PCI. The primary end point of the study will be the combined incidence of clinical events defined as the composite of 30-day death, myocardial infarction, repeat revascularization, catheter thrombus, stroke, thrombocytopenia, bailout use of glycoprotein IIb/IIIa inhibitors, and major or minor bleeding. CONCLUSION/CONCLUSIONS:The EMINENCE trial will assess the safety and feasibility of M118 as an anticoagulant in the setting of PCI and will provide important information to determine the appropriate therapeutic range of activated clotting time for M118 and the appropriate dose or doses to be explored in a phase 3 clinical trial.

BACKGROUND:Interest in the biology of endogenous progenitor cells (EPCs) continues to grow as evidence of their role in vascular repair mounts. EPC enumeration requires specialized laboratory techniques and is performed immediately after sample acquisition, limiting the clinical contexts in which EPC enumeration can be performed and the ability to increase sample sizes through multi-center participation. METHODS:We compared the numbers of EPCs enumerated in samples processed immediately after acquisition (n = 36) with EPCs enumerated in specimens stored for 24 hours or after cryopreservation of mononuclear cells (MNC) using two EPC identification strategies: cell surface marker expression (CD133/CD34) and aldehyde dehydrogenase activity (ALDH(br) cells). RESULTS:EPCs assessed in fresh samples correlated with EPCs enumerated after whole blood storage (r = 0.699 for CD133(+)CD34(+) cells, r = 0.880 for ALDH(br) cells, P < 0.005 and P < 0.0001, respectively) or mononuclear cryopreservation (r = 0.590 for CD133(+)CD34(+) cells, r = 0.894 for ALDH(br) cells, P < 0.0001 for each); however, correlation based on assessment of ALDH(br) cells was higher (P < 0.0003 for comparison of correlation coefficients). Initial results from a multi-site clinical trial suggest that EPC enumeration after mononuclear cell cryopreservation is feasible. CONCLUSION/CONCLUSIONS:EPC analysis based on ALDH activity is reproducible, even after extended whole blood storage or MNC cryopreservation.

Antiplatelet therapy is the cornerstone of management in acute coronary syndromes (ACS) and percutaneous coronary intervention. Combination therapy with aspirin and clopidogrel reduces the risk of death, myocardial infarction, or stroke in ACS but increases the risk of major bleeding, which studies indicate is 1%-4% higher when clopidogrel is added to aspirin. Given the association between bleeding and adverse outcomes, minimizing bleeding risk is a clinical priority. This review outlines strategies to reduce both acute and chronic bleeding risk with aspirin and clopidogrel and focuses on dosing of concomitant therapies, vascular access techniques, and mitigating the bleeding risk associated with coronary artery bypass grafting surgery.

Guidelines support percutaneous coronary intervention (PCI) of the noninfarct-related artery during primary PCI for ST-segment elevation myocardial infarction (STEMI) in patients with hemodynamic compromise; however, in patients without hemodynamic compromise, PCI of the noninfarct-related artery is given a class III recommendation. We analyzed the National Cardiovascular Data Registry (n = 708,481 admissions, 638 sites) to determine the prevalence, predictors, and in-hospital outcomes of primary multivessel PCI from 2004 to 2007. Patients with STEMI and multivessel coronary artery disease who were undergoing primary PCI were identified (n = 31,681). After excluding the patients treated with staged PCI (n = 2,745), 10.8% (n = 3,134) of the remaining population (n = 28,936) were treated with multivessel PCI. Patients undergoing multivessel PCI were at higher risk and were more likely to be in cardiogenic shock. The overall in-hospital mortality rates were greater in patients undergoing multivessel PCI (7.9% vs 5.1%, p <0.01). Among patients with STEMI and cardiogenic shock (n = 3,087), those receiving multivessel PCI had greater in-hospital mortality (36.5% vs 27.8%; adjusted odds ratio 1.54, 95% confidence interval 1.22 to 1.95). In conclusion, these data suggest that performing multivessel PCI during primary PCI for STEMI does not improve short-term survival even for patients with cardiogenic shock. These findings suggest the need for definitive studies to evaluate the utility of noninfarct-related artery PCI among patients with STEMI.