You will be given a definition of a task first, then some input of the task.
Given an abstract, generate a keyword (a noun phrase) that best describes the focus or contribution of the paper. Such keywords can be directly from the given abstract or outside it.

Abstract: Antithrombotic therapy in prevention and management of stroke is evolving rapidly as new clinical data better define indications. Stroke is a syndrome with several pathophysiologic bases, not one clinical entity. Optimal use of medical and surgical therapy requires definition of the specific mechanism of brain ischemia in the individual patient.
Output:
Aspirin