Assessment for futility

Coronary angiography is performed to evaluate for obstructive coronary artery disease. This is commonly performed via the transfemoral or transradial approach with the latter increasing in frequency. One of the most common complications of transradial access is radial artery occlusion occurring in ~5% of patients which prohibits the use of the radial artery in the future. There is evidence to support the use of intraprocedural anticoagulation to mitigate the risk of radial artery occlusion however the role of post-procedural anticoagulation has not been previously evaluated. Rivaroxaban is a direct oral anticoagulant (DOAC) with a safety profile superior to that of vitamin K antagonists. Given the safety profile, ease of use, and feasibility of DOAC therapy, our study will endeavor to evaluate the use of rivaroxaban 15mg orally once daily for 7 days after transradial access and the impact this has on the rate of radial artery occlusion.

Assessment of the coronary artery anatomy is commonly performed by coronary angiography (CA), which is the gold standard for evaluation of obstructive coronary artery disease (CAD). Coronary revascularization, opening of obstructed vessels, is most commonly performed by percutaneous coronary intervention (PCI) in patients with obstructive CAD. Traditionally, PCI is performed with implantation of one or more permanent metallic stents which act as a scaffold for arterial recoil and, in the case of drug eluting stents (DES), provide a platform for delivery of anti-proliferative agents. The transradial access (TRA) has rapidly emerged as the preferred vascular access site for CA and PCI with more than 50% of all coronary angiograms being performed via this approach.

There are several advantages to TRA for angiography including rapid hemostasis, early ambulation after the procedure thereby improving patient comfort and experience, and a decrease in the length of hospital stay. There is also a reported reduction in all-cause mortality, major adverse cardiovascular events, major bleeding, and vascular complications with TRA as compared to transfemoral access. However, radial artery occlusion (RAO) remains an important complication of this procedure as it precludes the reuse of this artery for future transradial approaches as well as the use of the vessel as a conduit for coronary artery bypass grafting.

Reports of RAO post-TRA has varied in the literature from ~4-10% in observational and randomized trials. In the largest systematic review published to date, the overall rate of RAO was 5.2% amongst the 46,631 subjects across 92 studies between 1989 and 2016. This systematic review also noted that the rate of early (i.e. <7 days) vs. late (i.e. >7 days) RAO was significantly higher which is suggestive of late recanalization in some patients. The factors which affect recanalization are not clear however standard of care involves administration of heparin during the procedure and patent hemostasis following the procedure. Patent hemostasis is performed by applying a delicate balance of pressure to prevent bleeding but not to the point of completely occlude the blood vessel and cessation of blood flow distally.

Numerous trials have explored the role of anticoagulation during angiography to reduce RAO and a recently published systematic review and meta-analysis demonstrated more intensive anticoagulation is protective. Indeed, this remains an active area of research with numerous ongoing trials evaluating the effect of intensive or higher dose anticoagulation during the procedure for prevention of RAO. Additionally, there were higher rates of RAO with diagnostic angiography as opposed to PCI purportedly as the latter involves higher doses of anticoagulation.

Direct oral anticoagulant (DOAC) therapy has provided a safer alternative with an improved bleeding profile over vitamin K antagonist anticoagulation therapy. The use of DOACs in cardiovascular medicine ranges from various conditions including stroke prevention in atrial fibrillation7-12 to venous thromboembolism13-16 to stable cardiovascular disease.

While intraprocedural anticoagulation has been studied extensively, a course of anticoagulation therapy post-TRA has not been studied. Given the safety profile, ease of use, and feasibility of DOAC therapy, our study will endeavor to evaluate the use of rivaroxaban 15mg orally once daily for 7 days after transradial access and the impact this has on the rate of RAO. Should this study prove to be positive, this could impact our routine standard of care with respect to having a strategy which could reduce the rate of this complication thereby preserving the radial artery for future access and/or as a conduit for coronary artery bypass grafting.

Inclusion Criteria:

1. Willing and able to provide written informed consent
2. Age ≥ 18 years
3. Diagnostic coronary angiography or percutaneous coronary intervention via the transradial approach

Exclusion Criteria:

1. Presence of a palpable hematoma or clinical concern of hemostasis at the transradial access site

2. Access or attempted access at a second site - including contralateral radial artery, brachial, or femoral artery or vein

3. Planned staged procedure, CABG or noncardiac surgery within 30 days

4. Contraindication or high risk of bleeding with anticoagulation

   1. bleeding requiring medical attention in the previous 6 months
   2. thrombocytopenia (platelets<50 x 109/L)
   3. prior intracranial hemorrhage
   4. use of IIb/IIIa during percutaneous coronary intervention
   5. administration of thrombolytic therapy in the preceding 24 hours
   6. use of non-steroidal anti-inflammatory medications
   7. ischemic stroke or transient ischemic attack diagnosed in the last 3 months

5. Cardiogenic shock

6. Ventricular arrhythmias refractory to treatment

7. Liver dysfunction (Child-Pugh class B or C)

8. Unexplained anemia with a Hgb below 100 g/L

9. History of medication noncompliance or risk factor for noncompliance

10. Active malignancy

11. Allergy to rivaroxaban

12. Another indication for anticoagulation

13. CYP3A4 and P-glycoprotein inhibitor use

14. Life expectancy <30 days

15. Women capable of pregnancy not on birth control

16. Chronic kidney disease with creatinine clearance of less than 30mL/min

17. History of antiphosphopholipid antibody syndrome