Evolution of Clinical Thinking and Practice Regarding Aspirin: What Has Changed and Why?

Aspirin (ASA) is the original antiplatelet agent. Its routine use, long unquestioned for both primary and secondary prevention in cardiovascular disease, is under increasing scrutiny as the risk:benefit balance for ASA becomes less clear and other disease- and risk-modifying approaches are validated. It can be viewed as a significant advance in evidence-based medicine that the use of an inexpensive, readily available, long-validated therapy is being questioned in large, rigorous trials. In this overview we present the important questions surrounding a more informed approach to ASA therapy: duration of therapy, assessment of net clinical benefit, and timing of start and stop strategies. We also consider potential explanations for "breakthrough" thrombosis when patients are on ASA therapy. Other manuscripts in this Supplement address the specifics of primary prevention, secondary prevention, triple oral antithrombotic therapy, and the future of ASA in cardiovascular medicine.