Dual antiplatelet therapy after stenting in all-comers, ACS patients and in high bleeding risk

There is an ongoing search for the optimal medical treatment of patients with symptomatic coronary artery disease. Dual antiplatelet therapy has emerged as an effective treatment in patients undergoing percutaneous coronary intervention with stent implantation, and it has reduced the incidence of worrying adverse events such as stent thrombosis and myocardial infarction. Compared to the long-established drug clopidogrel (besides aspirin), newer and more potent antiplatelet drugs have been introduced with promising results in randomized clinical trials that showed a reduction in ischemic events in patients with acute coronary syndromes. However, the favourable study effects were at least partly counterbalanced by some undesirable (side) effects, especially by an increase in the risk of major bleeding. Furthermore, clinical trial participants represent a somewhat “selected” patient population and therefore, “real world” studies remain essential to assess the effects of new drugs in patients who are treated in daily clinical practice. This may be even more important as ongoing refinement and new development of medical therapy may soon outdate the findings of previous studies. Notably, drug-eluting stents have been constantly improved to enhance the safety and efficacy of percutaneous coronary intervention. As a result of this progress in stent technology, the favourable effects of newer antiplatelet agents may be less obvious after treatment with new-generation drug-eluting stents, but in clinical practice the undesirable side effects do remain.

While physicians rely on clinical trial results and treat most of their patients accordingly, specific patient subgroups may benefit from a different treatment strategy that is tailored to their needs and risk profile. This includes high bleeding risk patients who have a particularly high risk of both, major bleedings and (recurrent) ischemic events.

This thesis assessed patients with acute coronary syndromes, who underwent percutaneous treatment with contemporary drug-eluting stents, in order to evaluate the impact of a guideline-recommended change in dual antiplatelet therapy from clopidogrel- to ticagrelor-based dual antiplatelet therapy. A special focus has been laid on the clinical outcome of high bleeding risk patients, a subgroup of patients that is currently underreported. In addition, the safety and efficacy of new-generation drug-eluting stents was assessed with particular attention to clinical outcome beyond the first year after stenting, as Dutch cardiologists generally discontinue dual antiplatelet therapy after 12 months from a percutaneous coronary intervention.