Anti-thrombotic medications for the neurointerventionist: aspirin and clopidogrel

The majority of neurological complications encountered during neuroendovascular procedures are a result of thromboembolic phenomena. This has become increasingly evident as techniques have evolved to incorporate an ever-growing volume of temporary and permanently implanted adjunctive devices. By optimizing our anti-thrombotic management strategies we can potentially improve procedural safety. The appropriate selection of anti-thrombotic regimens for neurointerventional procedures poses a unique set of challenges when compared with endovascular interventions in other vascular territories. Neurological procedures frequently target lesions that have hemorrhaged or have a lethal hemorrhagic potentiald-thus requiring that the operator maintain a tenuous balance between bleeding and thrombosis. Neurological end-organs are unforgiving, even of small emboli, further magnifying the implications of inadequate therapy. The spectrum of disease processes encountered within the context of routine clinical practice is very heterogeneous and each lesion requires a specific anti-thrombotic strategy. The diseases treated (eg, aneurysms, AVM, acute ischemic stroke, chronic atherosclerotic stenosis) are relatively uncommon in comparison with coronary or peripheral atherosclerotic disease. The field of neurointervention itself is still relatively new and continues to evolve rapidly, with innovation frequently outpacing clinical evidence. Predictably, within this environment, there are no large, controlled trials to guide anti-thrombotic management in most cases. For these reasons, medical decision making is based largely upon an understanding of the pharmacology of the agents used and an extrapolation of the literature from other fields. In this review we discuss aspirin and clopidogrel, the two anti-platelet agents commonly used in conjunction with endovascular stents and stent-like devices. We will discuss their pharmacology and applications in neuroendovascular therapeutics with a focus on practical solutions to dilemmas that are encountered during the course of daily clinical practice.