**1. Introduction**

Because of a global change in illness and death from infectious to noninfectious causes during the 20th century, life expectancy doubled and global population quadrupled [1]. Cardiovascular diseases (CVDs) have surpassed cancer as the main cause of mortality, with low- and middle-income countries bearing the brunt of the burden [2].

In 2015, the United States spent more than \$200 billion on heart problems, including related medications and health-care services [3]. In 2017, the American Cardiology Association reported that more than 360,000 persons were diagnosed with coronary heart disease [4].

The principal therapy for preventing arterial thrombosis in CVD patients is platelet inhibitors [5, 6]. Dual antiplatelet therapy (DAPT) with aspirin and a P2Y12 inhibitor is the standard medical treatment for patients with acute coronary syndrome (ACS) and those undergoing percutaneous coronary intervention (PCI) with an intracoronary stent [6].

Every year, about 1.2 million patients get DAPT after receiving a drug-eluting stent (DES). DAPT is used for a variety of cardiologic, neurologic, and surgical indications where the need to prevent thromboembolic events outweighs the risk of bleeding [7, 8]. DAPT is widely used to treat thrombotic stroke, coronary artery disease (CAD), peripheral vascular diseases, and transient ischemic attack (TIA). When compared to aspirin alone, DAPT with aspirin and clopidogrel has been shown to enhance clinical outcomes in patients with acute coronary syndrome or PCI [9, 10].

Despite the effectiveness of DAPT in preventing primary and subsequent myocardial infarction (MI) and stroke, there is an increased associated risk of spontaneous intracerebral hemorrhage (ICH) [11]. Interestingly, in-hospital mortality is greater in patients with ICH who are on DAPT compared to other antiplatelet agents [12, 13]. The goal of achieving efficient antiplatelet activity while avoiding gastrointestinal (GI) injury and bleeding has become a key focus in the management of thrombotic disease patients. This chapter is meant to explore on dual antiplatelet therapy highlighting the current guidelines and recent evidences on the indications, dosing, and duration of treatment using dual antiplatelet therapy.
