Aspirin is the prophylactic antiplatelet drug of choice for people with cardiovascular disease. Adding a second antiplatelet drug to aspirin may produce additional benefit for those at high risk and those with established cardiovascular disease.
Squizzato, A., Keller, T., Romualdi, E., & Middeldorp, S. (2011). Clopidogrel plus aspirin versus aspirin alone for preventing cardiovascular disease. Cochrane Database of Systematic Reviews. https://doi.org/10.1002/14651858.cd005158.pub3