**5. Evidence for DAPT duration after PCI in ACS setting**

The three sets of guidelines provide strong recommendation for a standard 12-month DAPT treatment after an ACS, based on the CURE trial and the PCI-CURE substudy published nearly two decades ago, in which DAPT with aspirin and clopidogrel was prescribed for 3 to 12 months after PCI [36, 37]. More recently, the pivotal prasugrel and ticagrelor trials, conducted in patients with ACS, used a 12-month default DAPT duration, furthermore establishing this approach as the standard of practice (**Table 1**) [38, 39].

#### **5.1 Scenarios for shortened DAPT**

Due to the time gap between the latest ESC guidelines on this topic and its American and Canadian counterparts, recommendations on minimal DAPT duration differ between the former and the latter (**Table 1**). The scarce evidence available at the time of the last ACC/AHA and CCS guidelines led to only weak recommendation for a 6-month DAPT on the former, while the latter holds at a 12-month recommendation. This year's ESC guidelines on the management of ACS in patients presenting without persisting ST-segment elevation includes various guidance on short DAPT.

As discussed previously, the insight from the PRECISE-DAPT study led to consider a shortened 3-month DAPT duration in patients at HBR (PRECISE-DAPT score ≥ 25) (Recommendation IIa B) [13]. What is probably more interesting, however, is the evidence gathered recently on patients at low-to-intermediate ischemic risk and low bleeding risk. The previously described TWILIGHT and SMART-CHOICE trials included a high proportion of patients presenting with ACS (64.8% and 58.2%, respectively), with the benefits of antiplatelet monotherapy

being consistent between subgroups. On the other hand, the SMART-DATE trial [40] specifically assessed 6 versus 12-month DAPT in patients with ACS. Although mortality, stroke and BARC type 2–5 bleeding did not differ between the two groups, the rate of myocardial infarction was higher in the short DAPT group. Combining the information of these three trials, the ESC guidelines suggest a 3 to 6-month DAPT therapy depending on the balance of ischemic and hemorrhagic risk in a Class IIa, level A recommendation. The recent TICO trial evaluated another aspirin-free strategy, specifically among patients undergoing PCI for an ACS [41]. Ticagrelor monotherapy after 3 months of DAPT resulted in a slight, significant reduction of the composite outcome of major bleeding and cardiovascular events at one year, compared with a ticagrelor-based 12-month DAPT.
