The purpose of this study is to compare the use of ticagrelor alone versus ticagrelor and aspirin together. Both ticagrelor and aspirin stop platelets from sticking together and forming a blood clot that could block blood flow to the heart. This study will look to determine the effectiveness and safety of ticagrelor alone, compared to ticagrelor plus aspirin in reducing clinically relevant bleeding and in reducing ischemic adverse events among high-risk patients who have had a percutaneous intervention with at least one drug-eluting stent. A patient is considered high-risk if they meet certain clinical and/or anatomic criteria.

Up to 9000 subjects will be enrolled at the time of their index PCI. Subjects meeting randomization eligibility criteria at 3 months post enrollment will be randomized to either ticagrelor plus aspirin or ticagrelor plus placebo for an additional 12 months. Follow-up clinic visits will be performed at 3 months, 9 months and 15 months post enrollment.

This is a multicenter, prospective, blinded dual-arm study. Up to 9000 high-risk patients who have undergone successful PCI with at least one locally approved drug eluting stent discharged on DAPT with aspirin and ticagrelor of at least 3 months intended duration from centers still to be determined in the U.S., Canada, Europe and Asia. The primary objective of this study is to determine the impact of antiplatelet monotherapy with ticagrelor alone versus DAPT with ticagrelor plus aspirin for 12 months in reducing clinically relevant bleeding (efficacy) among high-risk patients undergoing PCI who have completed a 3-month course of aspirin plus ticagrelor. The secondary objective of this study is to determine the impact of antiplatelet monotherapy with ticagrelor alone versus DAPT with ticagrelor plus aspirin for 12 months in reducing major ischemic adverse events (safety) among high-risk patients undergoing PCI who have completed a 3-month course of aspirin plus ticagrelor.

Exploratory objectives include assessing the comparative safety and efficacy of the different DAPT regimens for individual components of the primary efficacy and secondary safety objectives.

The primary analysis for TWILIGHT will be performed independently by the London School of Hygiene and Tropical Medicine

Inclusion Criteria:

• High-risk patients who have undergone successful PCI with at least one locally approved drug eluting stent discharged on DAPT with aspirin and ticagrelor of at least 3 months intended duration will be eligible for the TWILIGHT study.
• Enrollment into the study will require meeting at least one clinical inclusion, one angiographic inclusion and none of the exclusion criteria.

Clinical Inclusion Criteria:

• Adult patients ≥ 65 years of age
• Female gender
• Troponin Positive acute coronary syndrome
• Established vascular disease defined as previous MI, documented PAD or CAD/PAD revascularization
• Diabetes mellitus treated with medications (oral hypoglycemic, subcutaneous injection of insulin)
• Chronic kidney disease defined as an estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73m2 or creatinine clearance (CrCl) < 60 ml/min

Angiographic Inclusion Criteria:

• Multivessel coronary artery disease
• Target lesion requiring total stent length >30 mm
• Thrombotic target lesion(s)
• Bifurcation lesions with Medina X,1,1 classification requiring at least 2 stents
• Left main (≥50%) or proximal LAD (≥70%) lesion
• Calcified target lesion(s) requiring atherectomy

Exclusion Criteria:

• Under 18 years of age
• Contraindication to aspirin
• Contraindication to ticagrelor
• Planned surgery within 90 days
• Planned coronary revascularization (surgical or percutaneous) within 90 days
• Need for chronic oral anticoagulation
• Prior stroke
• Dialysis-dependent renal failure
• Active bleeding or extreme-risk for major bleeding (e.g. active peptic ulcer disease, gastrointestinal pathology with a raised risk for bleeding, malignancies with a raised risk for bleeding)
• Salvage PCI or STEMI presentation.
• Liver cirrhosis
• Life expectancy < 1 year
• Unable or unwilling to provide informed consent
• Women of child bearing potential. Defined: a woman is considered potential (WOBCP) following menarche and until becoming post-menopausal unless permanently sterile. Permanent sterilization methods include hysterectomy, bilateral salpingectomy and bilateral oophorectomy. a postmenopausal state is defined as no menses for 12 months without an alternative medical cause.
• Fibrinolytic therapy within 24 hours of index PCI
• Concomitant therapy with a strong cytochrome P-450 3A inhibitor or inducer
• Platelet count < 100,000 mm3
• Requiring ongoing treatment with aspirin ≥ 325 mg daily

1 year

All bleeding AE were reported in the intention-to-treat (ITT) cohort. - Placebo + Ticagrelor (N=3555) and Aspirin + Ticagrelor (N=3564)

All ischemic AE were reported in the per protocol (PP) cohort. - Placebo + Ticagrelor (N=3524) and Aspirin + Ticagrelor (N=3515)

All-cause mortality were reported in the per protocol (PP) cohort. - Placebo + Ticagrelor (N=3524) and Aspirin + Ticagrelor (N=3515)

Limitations include lack of power to detect differences in the risk of important yet rare clinical events, e.g stent thrombosis and stroke; and trial may not be generalizable to all patients undergoing PCI due to high risk criteria.