Optimal antithrombotic treatment during primary percutaneous coronary intervention?

Opposition: Unfractionated heparin should no longer be used in the catheterization laboratory

The goal of anticoagulation during percutaneous coronary intervention (PCI) is the primary and secondary prevention of thrombotic and significant bleeding events that increase cardiovascular morbidity and mortality. Unfractionated heparin is the most commonly-used anticoagulant, but low-molecular weight heparin, and more recently bivalirudin are becoming increasingly popular in cardiac catheterization laboratories¹.

The ACC/AHA/SCAI PCI guidelines² recommend a 70-100 IU/kg bolus of heparin to achieve an activated clotting time (ACT) of 250-300 seconds for Hemotec and 300-350 seconds for Hemochron systems, when glycoprotein IIb/IIIa inhibitors are not used. When glycoprotein IIb/IIIa inhibitors are used, a bolus of 50-70 IU/kg of unfractionated heparin is recommended to achieve an ACT of 200-250 seconds.

Point of care platelet activity measurement in primary PCI [PINPOINT-PPCI]: a protocol paper

Background

Optimal treatment of acute ST-elevation myocardial infarction (STEMI) involves rapid diagnosis, and transfer to a cardiac centre capable of percutaneous coronary intervention (PCI) for immediate mechanical revascularisation. Successful treatment requires rapid return of perfusion to the myocardium achieved by thromboaspiration, passivation of the culprit lesion with stent scaffolding and systemic inhibition of thrombosis and platelet activation. A delicate balance exists between thrombosis and bleeding and consequently anti-thrombotic and antiplatelet treatment regimens continue to evolve. The desire to achieve reperfusion as soon as possible, in the setting of high platelet reactivity, requires potent and fast-acting anti-thrombotic/anti-platelet therapies. The associated bleeding risk may be minimised by use of short-acting anti-thrombotic intravenous agents. However, effective oral platelet inhibition is required to prevent recurrent thrombosis. The interaction between baseline platelet reactivity, timing of revascularisation and effective inhibition of thrombosis is yet to be formally investigated.

Methods/Design

We present a protocol for a prospective observational study in patients presenting with acute STEMI treated with primary PCI (PPCI) and receiving bolus/infusion bivalirudin and prasugrel therapy. The objective of this study is to describe variation in platelet reactivity, as measured by the multiplate platelet function analyser, at presentation, the end of the PPCI procedure and 1, 2, & 24 hours post-procedure. We intend to assess the prevalence of high residual platelet reactivity within 24 hours of PPCI in acute STEMI patients receiving prasugrel and bivalirudin. Additionally, we will investigate the association between high platelet reactivity before and after PPCI and the door-to-procedure completion time.

This is a single centre study with a target sample size of 108 participants.

Discussion

The baseline platelet reactivity on presentation with a STEMI may impact on the effect of acute anti-thrombotic and anti-platelet therapy and expose patients to a heightened risk of bleeding or ongoing thrombosis. This study will define the baseline variation in platelet reactivity in a population of patients experiencing acute STEMI and assess the pharmacodynamic response to combined treatment with bivalirudin and prasugrel. The data obtained from this trial will be hypothesis generating for future trials testing alternative pharmacotherapies in the acute phase of treatment for STEMI.

Trial registration

This study has approval from Wiltshire research ethics committee (10/H0106/87) and is registered with current controlled trials (http://www.controlled-trials.com/ISRCTN82257414).