The investigators will be comparing the effects of two different drug treatment strategies, in patients with history of a heart attack, on different markers of bleeding and clotting risk. Both treatment strategies are already approved for the indication of improving outcomes in high-risk patients with history of heart attack.

The investigators will enroll patients with coronary disease >1 year after an acute coronary syndrome. Subjects will be randomized to one of two treatment plans. One plan the participant will take ticagrelor for one week, then take two weeks off with no drug (washout period), then one week of rivaroxaban. The other plan will be reverse order where the participant will take rivaroxaban for one week, then two weeks off(washout period), then one week of ticagrelor. Study drugs will be provided to participants at the start of each treatment period. Bleeding time will be determined and blood samples will be taken at four timepoints (baseline, post first drug, pre second drug, and post second drug) to measure complete blood count, CRP, and fibrin clot assessment. These are surrogate markers for safety (bleeding) and efficacy (increased thrombotic risk)

Inclusion Criteria:

• Patients with chronic coronary syndrome (at least 1 year after having a myocardial infarction) on aspirin monotherapy will be eligible for this study. They have to have at least one of these additional risk factors:

  1. Diffuse coronary artery disease.
  2. Peripheral vascular disease
  3. Diabetes
  4. Chronic kidney disease (eGFR<60 ml/unit/1.73 m2)

Exclusion Criteria:

• Allergy to either rivaroxaban or ticagrelor
• Requirement for anticoagulation or P2Y12 inhibitor therapy
• Anemia (hemoglobin < 10 g/dL)
• Severe renal impairment (eGFR < 30 ml/unit/1.73 m2)
• Bleeding disorders
• Significant liver impairment resulting in deranged clotting parameters
• Any history of intracranial hemorrhage
• Stroke within 6 months
• History of gastrointestinal bleed within 6 months
• Major surgery within 1 month
• Patients with inflammatory conditions
• Concomitant treatment with immunosuppressive therapy, inhibitors or inducers of P glycoprotein or CYP3A4 enzymes (eg. azole antifungals, ritonavir, erythromycin, clarithromycin, rifampicin)
• Concomitant treatment with antidepressants (selective serotonin reuptake inhibitors, serotonin and norepinephrine reuptake inhibitors)
• Pregnancy
• Inability to give written consent

Study personnel performing bleeding time and laboratory staff will be blinded to treatment allocation.