Antithrombotic Therapy in Acute Coronary Syndromes and Coronary Artery Ectasia

Coronary artery ectasia (CAE) is defined as a segmental or diffuse abnormal dilatation that exceeds more than 1.5 times the diameter of a normal adjacent coronary segment. The prevalence of CAE ranges from 0.3 to 4.9% and atherosclerosis is believed to be the most common etiology. According to angiographic findings, blood flow might be altered by the inappropriate dilatation in the affected arteries resulting in platelet activation and thrombus formation. Also, the presence of CAE has been related with elevated inflammatory markers and plasma soluble adhesion molecules which are an important component of vascular aneurysm formation.

Patients with MI and CAE have an increased risk of major adverse cardiovascular events (MACE) compared with those without CAE. However, it is unclear which is the optimal antithrombotic therapy for the prevention of recurrent ischemic events in patients with CAE after acute coronary syndrome (ACS)

OVER-TIME will be the first randomized controlled trial to provide insight into the safety and efficacy of different antithrombotic strategies in patients with CAE after an ACS event.

OVER- TIME is an investigator initiated, exploratory, open label, single center, randomized clinical trial comparing dual antiplatelet therapy (acetyl-salicylic acid plus a P2Y12 inhibitor) versus the combination of antiplatelet monotherapy (P2Y12 inhibitor) plus low dose anticoagulant (rivaroxaban, 15mg oral dose) for prevention of recurrent ischemic events in patients with established CAE and ACS. The trial protocol received local research and ethics committee approval and complies with the principles of the Declaration of Helsinki. Written informed consent was obtained from all patients prior to randomization.

Study patients are aged 18 or more, hospitalized with the diagnosis of ACS (NSTEMI \& STEMI) undergoing coronary angiogram showing CAE in the infarction culprit artery. CAE is defined as segmental or diffuse abnormal dilatation that exceeds more than 1.5 times the diameter of a normal adjacent coronary segment. The definition of a CAE case will be based on the opinion of two independent interventional cardiologists.

The study is considered a pilot, because no randomized controlled trial has been performed to compare the efficacy of different types of antithrombotic regimens in patients with CAE after ACS. Considering a power (1-β) of 80%, an alpha level of 0.05%, accounting on the event rates of approximately 5% in patients with oral anticoagulation versus 33% in patients with dual antiplatelet therapy at 1 year of follow- up, and assuming 10% losses, the investigators calculated a sample size of 60 patients (30 per arm) for the study.

Patients are screened for the eligibility criteria during hospitalization and are randomized using 4x4 permuted blocks, after providing informed consent. Patients and treating physicians are not blinded to the allocation arm.

Patients are randomized in a 1:1 ratio to receive during 12 months a daily oral dose of DAPT (acetyl-salicylic acid 100 mg and clopidogrel 75 mg) or the combination of SAPT (clopidogrel 75 mg) and low dose of anticoagulant (rixaroxaban 15 mg). Patients will be followed for 12 months in 3 pre-specified visits (30 days, 6 months and 12 months after hospitalization). At each visit, basic clinical data will be recorded and clinical events (both ischemic and hemorrhagic, as well as safety and adverse drug events) will be actively screened.

The study has 2 co-primary endpoints, including (1) efficacy in prevention of MACE defined as the composite of cardiovascular death, non-fatal infarction, and repeated revascularization; and (2) security in major and minor bleeding, defined as a composition of major and minor bleeding events using the Bleeding Academic Research Consortium (BARC) classification.

Additionally, there are 3 secondary endpoints, including (1) the composite of net clinical benefit defined as a composite of cardiovascular death, non-fatal infarction, repeated revascularization, and major \& minor bleeding events according to the BARC classification; (2) the individual components of the 2 co-primary endpoints, and (3) to compare the fibrin clot properties, by the analysis of clot lysis time and maximum turbidity, at recruitment and at 6 month of treatment.

Other clinically relevant variables such as baseline characteristics, personal history, clinical presentation, LVEF, high sensitivity cardiac troponin, NTproBNP, renal function, interventional aspects of treatment (such as stent placement, number of affected vessels, quantitative coronary angiography characterization) and other concomitant treatments will also be measured by the research staff during index event and subsequent visits.

Both the co-primary endpoints will be evaluated using the time to the occurrence of the first event. Time to the occurrence of the primary outcome and its components will be evaluated with Kaplan- Meier estimates, Log Rank Test and Cox proportional hazard models. Alternatively, analysis by "Win ratio" will be performed. For secondary outcomes, chi-squared test, T test or Wilcoxon Rank- Summation Test will be used, as appropriate.

Plasma samples will be collected from patients randomized in any group of antithrombotic therapy to analyze fibrin clots with special interest to study clot lysis time and maximum turbidity (a measure of clot density) to determine fibrin clot properties associated with clinical outcomes following CAE and ACS. This analysis may provide additional, surrogate data, as clot lysis time has been significantly associated with a higher risk of recurrent ischemic events in the long term () .