Anticoagulation strategies for patients undergoing percutaneous coronary intervention: unfractionated heparin, low-molecular-weight heparins, and direct thrombin inhibitors

The thrombin hypothesis in ACS: a disappointing disconnect between bench data and bedside clinical trials

Studies have demonstrated the efficacy and safety of unfractionated heparin and low-molecular-weight heparin in the management of patients with acute coronary syndrome. However, a common limitation of unfractionated heparin and low-molecular-weight heparin is that neither can neutralize clot-bound thrombin. To overcome this limitation of the broad heparin-based anticoagulants, novel anticoagulants targeted for both the free and clot-bound forms of thrombin (direct thrombin inhibitors), or other individual components of the coagulation cascade (eg, direct and indirect factor Xa inhibitors), were developed. These targeted anticoagulation agents showed promising results in preclinical testing and have been evaluated in large-scale clinical acute coronary syndrome trials. This review discusses the disconnect between the excellent preclinical findings obtained with these novel, targeted agents and the efficacy and safety data observed in patients with acute coronary syndrome, compared with the broader-range heparin-based anticoagulants.

Percutaneous Coronary Intervention–Related Bleeding Risk Factors in Current Practice

BACKGROUND:

Bleeding is a common and costly complication of percutaneous coronary intervention (PCI). Little is known about the risk factors for bleeding complications.

Objective:

To report our PCI-related observations from a single institution and use the information to establish risk factors for short-term bleeding complications, with special focus on examining the importance of renal function.

METHODS:

A retrospective record review was conducted of the admission of 300 patients grouped according to antithrombotic regimen: unfractionated heparin alone (n = 187), bivalirudin (n = 26), and glycoprotein IIb/IIIa antagonist plus heparin (n = 103). Bleeding and ischemic outcomes were tracked. A model was constructed to predict independent bleeding risk factors.

RESULTS:

Treatment groups differed significantly regarding any bleeding (p = 0.001), minor bleeding (p < 0.001), and length of stay (p = 0.01). Multivariate predictors of any bleeding included antithrombotic regimen, creatinine clearance (Clcr) <30 mL/min, and hypertension. Any bleeding was associated with prolonged length of stay. Major bleeding was predicted by Clcr <30 mL/min and was associated with prolonged length of stay and death. Minor bleeding was predicted only by choice of antithrombotic regimen.

CONCLUSIONS:

The major influences on bleeding risk appeared to be Clcr <30 mL/min and choice of antithrombotic regimen. It is important to note that other markers of renal function, including serum creatinine value and serum creatinine at a cutoff level of 1.5 mg/dL, did not predict bleeding events.

Prevention of cardiovascular outcomes in type 2 diabetes mellitus: trials on the horizon

There has been an explosion of interest in CVD and diabetes mellitus because of the epidemic nature of the diseases and their tight epidemiologic link. Clinical trials over the past decade have built substantial evidence for the role of lipid management, blood pressure control, and antiplatelet therapy in managing risk for CVD in patients who have diabetes mellitus. The many clinical trials underway will not only hone existing recommendations by establishing appropriate targets and techniques for lipid and blood pressure management, but also should demonstrate the role and most appropriate techniques for management of glycemia, flow-limiting coronary lesions, and obesity.

Bivalirudin

Bivalirudin (Angiox, Angiomax) is a synthetic 20-amino acid peptide analogue of hirudin. It is a direct thrombin inhibitor that binds specifically and reversibly to both fibrin-bound and unbound thrombin. Intravenous bivalirudin is approved in Europe for use as an anticoagulant in patients undergoing percutaneous coronary intervention (PCI). In the US, bivalirudin is approved in patients with unstable angina pectoris undergoing percutaneous transluminal coronary angioplasty (PTCA) and has recently been approved for use with provisional glycoprotein (GP) IIb/IIIa inhibition in patients undergoing PCI. Bivalirudin plus provisional GP IIb/IIIa inhibition is effective in patients undergoing PCI. The large, well controlled REPLACE-2 (Randomized Evaluation in PCI Linking Angiomax to Reduced Clinical Events) study showed that bivalirudin plus provisional GP IIb/IIIa inhibition was noninferior to heparin plus planned GP IIb/IIIa inhibition and that bivalirudin was associated with a reduced risk of bleeding complications. In patients with heparin-induced thrombocytopenia (HIT), bivalirudin was effective against ischaemic events and there was a low incidence of bleeding complications. Bivalirudin should be considered as an alternative to heparin plus planned GP IIb/IIIa inhibition in any patient undergoing urgent or elective PCI, especially in any patient with a high risk of bleeding complications.