Prof. Robert F. Storey
Risk of stent thrombosis is strongly determined by antiplatelet drug response, duration of antiplatelet therapy and technical factors that influence the success of coronary stent implantation.
Dietmar Trenk described the importance of response to clopidogrel as a determinant of stent thrombosis risk. Many studies have shown how ‘high on-treatment platelet reactivity’ in clopidogrel-treated PCI patients, as determined by several platelet function tests that assess response to ADP, independently increases ST risk. On the other hand, high levels of platelet inhibition on clopidogrel may increase the risk of bleeding.Both prasugrel and ticagrelor have demonstrated greater efficacy in preventing stent thrombosis compared to clopidogrel and more work is required to define their place in elective PCI for stable coronary artery disease.
Jurrien ten Berg presented the historical evidence for recommending up to 1 year of dual antiplatelet therapy (DAPT) following drug-eluting stent (DES) implantation and highlighted some of the uncertainties in this area that need to be addressed in future studies.The PRODIGY study showed no benefit of extending DAPT beyond 6 months, with increased bleeding rates seen in the group randomised to 24 months DAPT. Evolving stent technology is likely to influence the recommended duration of DAPT in the future but individualisation of DAPT duration, bearing in mind multiple contributors to stent thrombosis and bleeding risks, is likely to guide decision-making.Giulio Guagliumi demonstrated how OCT can discriminate different causes of ST such as malapposition, occlusive restenosis and ‘neoatherosclerosis’ comprising lipid-laden neointima.Heterogeneity may be seen along the length of the DES with good and bad sections. This may be less of an issue with newer DES design but still neoatherosclerosis has been witnessed. Christoph Varenhorst pointed to the trade-off between delayed healing and restenosis, both of which contribute to stent thrombosis risk. Newer-generation DES have thinner polymer, reduced strut thickness and alternative drugs that may modulate the longer term risk of stent thrombosis, with recent meta-analysis favouring cobalt chromium, everolimus-eluting stents over bare-metal stents and some other DES.
Bioabsorbable stents offer the opportunity to explore the longer term efficacy of new stent technology. However, individual PCI technique remains important regardless of the available tools.
Session Title: What is new in stent thrombosis?
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