On the use of abciximab in percutaneous coronary intervention

    Abstract

    Introduction: The present thesis ´On the use of abciximab in percutaneous coronary intervention´ is based on 6 papers concerning the glycoprotein IIb/IIIa inhibitor, abciximab. The thesis is divided into 2 sections. One section concerning a randomized trial comparing intracoronary (IC) with intravenous (IV) abciximab in patients with ST-segment elevation myocardial infarction (STEMI) treated with primary percutaneous coronary intervention (pPCI), and one section concerning results from 3 registry studies on the effect of abciximab in distinct subgroups of patients with acute coronary syndrome (ACS).

    Optimal administration route of abciximab.
    A randomized study

    Background: The glycoprotein IIb/IIIa inhibitor, abciximab, is used as an adjuvant anti-platelet therapy in PCI-treated patients suffering from ACS. A subgroup of patients with ACS is those with STEMI treated with pPCI. Recommendations on the use of abciximab in this setting are based on trials showing clinical benefit of IV bolus of abciximab compared to placebo. However, it has been speculated, that by administering the initial bolus of abciximab IC, a higher local concentration of the drug could be obtained, and this might confer an even more beneficial effect. Firstly, we searched the literature on the subject and found that no large-scaled randomized trials had been published. Most data were derived from small studies evaluating non-clinical endpoints or were of retrospective design. This overview is published as a review (paper I).

    Objectives and methods: In order to investigate if IC administration of bolus abciximab indeed was superior to IV administration, we set up a randomized, open-label, single-center trial. We randomized 355 STEMI patients treated with pPCI between 2006 and 2008 to receive either IC or IV bolus of abciximab. Patients were subsequently contacted for follow-up after 30 days and 1 year, with regards to the endpoints: mortality, need for target vessel revascularization (TVR), and new myocardial infarction (MI).

    Results: Of the 355 patients randomized, 185 received IC bolus and 170 IV bolus of abciximab.
    The main results are the following:
    • After 30 days, significantly fewer patients in the IC arm had died or had the need for TVR. We found no difference in the risk of MI. These results are presented in paper II.
    • After 1 year, significantly fewer patients in the IC arm had died, had the need for TVR, or had experienced a new MI. These results are presented in paper III.

    Conclusion: In the setting of pPCI-treated STEMI patients, IC bolus administration of abciximab is superior to IV bolus administration with respect to mortality, TVR and MI.

    Differences in the effect of abciximab in 3 subgroups of patients.
    Three register studies

    Background: Large randomized trials performed from the beginning of the 1990´ies and until now, have overall shown beneficial effects of abciximab in different settings. However, post hoc analyses and dedicated trials have shown that some subgroups of patients might benefit more than others, and that abciximab might even be harmful in yet others. Although data are not consistent, suggestions have been made, that risk factors, such as diabetes, age and complexity of the coronary lesions might influence the efficacy of abciximab.

    Objectives and methods: In order to assess the efficacy of abciximab among ACS patients with the above risk factors, we merged data from the 3 registries: 1) P-base, which is the dedicated PCI database at Gentofte University Hospital, containing baseline and procedural data; 2) The National Person Identification Registry which holds data on vital status; and 3) The Danish National Board of Health´s National Patient Registry which holds data on discharge ICD-10 codes and thus clinical endpoints. By doing so, we were able to evaluate the efficacy in the three following settings:
    • ACS patients with diabetes (paper IV): 5,003 patients with ACS treated with PCI were stratified by diabetes status and use of abciximab. Follow-up was a maximum of 3 years. The endpoints were: mortality, TVR, MI, and the composite of the three.
    • Impact of age and abciximab in high risk ACS patients (paper V): 2,068 invasively treated ACS patients with complex lesions were stratified by age and use of abciximab. Follow-up was 1 year. The endpoints were: mortality, TVR, MI, and the composite of the three.
    • Impact of lesion type and abciximab in STEMI patients (paper VI): 2,935 STEMI patients treated with pPCI were stratified by type of lesions on angiogram (complex versus simple) and use of abciximab. Follow-up was 1 year. The endpoints were: mortality, TVR, MI, and the composite of the three.

    Results:
    • Patients with diabetes who experienced ACS and who were treated with PCI and abciximab had their mortality and need of TVR reduced significantly compared to diabetic patients who did not receive abciximab. Actually, diabetic patients (who have an a priori higher risk of adverse outcome) treated with abciximab had their risk of death or TVR reduced to a level similar to ACS patients without diabetes not treated with abciximab. Paper IV.
    • Patients with ACS who were older or equal 70 years of age did not seem to have the mortality benefit of abciximab seen in patients younger than 70 years of age. Paper V.
    • Among STEMI patients treated with pPCI, only those who had a complex lesion assessed by diagnostic coronary angiography had a mortality benefit from abciximab. Paper VI.

    Conclusion:
    • Our results support the use of abciximab in diabetic patients with ACS who undergo PCI.
    • In patients older or equal 70 years of age, abciximab should be used rarely and with caution, since no benefit on mortality could be detected and because elderly are known to have a higher risk of bleeding complication when treated with abciximab.
    • Since only STEMI patients with complex lesions benefitted from abciximab, a diagnostic angiogram should be performed in order to characterize the lesion before treatment with abciximab is initiated in STEMI patients and a general and upstream use of abciximab should be avoided.

    OriginalsprogEngelsk
    UdgivelsesstedGentofte Hospital
    ISBN (Trykt)978-87-92613-12-7
    StatusUdgivet - 2011

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