Abstract

Dual antiplatelet therapy (DAPT) is standard treatment for patients with acute coronary syndromes (ACS), typically comprising the use of aspirin with either an irreversible thienopyridine P2Y₁₂ inhibitor, clopidogrel or prasugrel, or reversibly binding ticagrelor. Pivotal studies led to guidelines recommending DAPT for up to 12 months post-ACS. Despite this, there remains a significant burden of coronary artery disease (CAD)-related events up to and after this period. Recent meta-analyses, including both patients with ACS and patients with stable CAD treated with DAPT following percutaneous coronary intervention, have suggested that long-term thienopyridine-based DAPT reduces the risks of myocardial infarction (MI) and stent thrombosis but may paradoxically increase all-cause mortality risk. The PEGASUS-TIMI 54 (Prevention of Cardiovascular Events in Patients with Prior Heart Attack Using Ticagrelor Compared to Placebo on a Background of Aspirin - Thrombolysis in Myocardial Infarction 54) study examined the effects of long-term DAPT with aspirin and ticagrelor, compared with aspirin alone, on major adverse cardiovascular events (MACE) and complications, including bleeding in patients with prior history of MI. It showed that, over a 3-year period, ticagrelor reduced the risk of MACE but increased non-fatal bleeding risk. Overall, the PEGASUS-TIMI 54 results demonstrate that patients with a history of ACS deemed to be at high risk of further ischaemic events, particularly those in whom the risks of ischaemic events and cardiovascular death outweigh the risk of life-threatening bleeding, may benefit from prolonged ticagrelor-based DAPT. Guidelines are emerging which reflect this. The relationship between aspirin and ticagrelor, particularly with regard to aspirin dosing, remains to be fully elucidated and attention has recently been turned to the option of ticagrelor monotherapy. Future studies will explore optimal individualised strategies for long-term antiplatelet therapy.