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Rocking the boat on Rivaroxaban. Manish Khullar, BSc Pharm Interior Health Pharmacy Resident August 15, 2013. Learning Objectives. Describe the risk assessment of stroke for atrial fibrillation List therapeutic alternatives for stroke prevention
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Rocking the boat on Rivaroxaban Manish Khullar, BSc Pharm Interior Health Pharmacy Resident August 15, 2013
Learning Objectives • Describe the risk assessment of stroke for atrial fibrillation • List therapeutic alternatives for stroke prevention • Explain the role of rivaroxaban in patients with atrial fibrillation and aortic valve replacement
Anticoagulant history • Diagnosed with atrial fibrillation this year and placed on warfarin (INR 2-3) 2 months ago • Was on warfarin for 1 month but did not tolerate side effects (insomnia, headaches, vomiting) • GP switched him to rivaroxabanlast month and has been on it since admission
Investigations • Diagnostics: • Chest x-ray (upon admission): • Left sided pleural effusion • Mild right sided pleural effusion • ECHO: • Pending • Ejection fraction from Jan 2013: 40-45% • Endoscopy • Pending
Course in Hospital • Admitted to investigate shortness of breath and worsening CHF • Endoscopy identified gastric ulcer • Transfused with 2 units of blood
List of DRPs • JF is at risk of stroke secondary to not receiving any anticoagulation therapy for his atrial fibrillation and would benefit from reassessment of his stroke prophylaxis therapy. • JF is at risk of stroke secondary to not receiving antithrombotic therapy with AVR and would benefit from reassessment of his stroke prophylaxis therapy. • JF is at risk of death and hospitalizations secondary to receiving too low dose of atorvastatin despite his high risk and would benefit from reassessment from his prophylaxis therapy. • JF is at risk of death and hospitalizations secondary to not receiving an ACE inhibitor or ARB for MI prophylaxis and would benefit from reassessment of therapy.
List of DRPs • JF is at risk of death and hospitalizations secondary to not receiving antiplatelet therapy for post-MI and would benefit from reassessment of therapy. • JF is at risk of death and hospitalizations secondary to not receiving an ACE inhibitor or ARB despite having congestive heart failure and would benefit from reassessment of his congestive heart failure therapy. • JF is at risk of experiencing adverse effects of metformin secondary to being on metformin despite poor renal function and would benefit from reassessment of his therapy. • JF is at an increased risk of bleeding, stroke/death due to unclear efficacy in rivaroxaban in AVR patients and would benefit from reassessment of therapy.
DRP Focus • JF is at risk of stroke secondary to not receiving any anticoagulation therapy for his atrial fibrillation and would benefit from reassessment of his stroke prophylaxis therapy. • JF is at risk of stroke secondary to not receiving antithrombotic therapy with AVR and would benefit from reassessment of his stroke prophylaxis therapy. • JF is at an increased risk of bleeding, stroke/death due to unclear efficacy in rivaroxaban in AVR patients and would benefit from reassessment of therapy.
Background • Stroke occurs in atrial fibrillation due to blood stasis in atria leading to clot formation inside the chambers • Upon cardioversion to NSR, the clot may eject and stroke can occur
Assessing Risk of Stroke in Atrial Fibrillation • Stroke assessment tool: CHADS2
Need for Antithrombotics in AVR • Patients with prosthetic valves are at risk of thromboembolic complications (stroke, valve obstruction and/or regurgitation) • Risk is higher with mechanical valves than with bioprosthetic valves • Risk is higher with mitral than aortic prosthetic valves • Making antithrombotic therapy necessary in these patients
Goals of Therapy • Reduce mortality • Reduce morbidity (strokes, hospitalizations) • Prevent adverse events • Improve quality of life
Antithrombotic Alternatives for AVR • CHEST guidelines: • “in patients with aortic bioprosthetic valves, who are in sinus rhythm, and have no other indication for VKA therapy, we recommend ASA (50-100mg/d)” CHEST 2008
Antithrombotic Alternatives for AVR • CHEST guidelines: • “in patients with bioprosthetic valves who have additional risk factors for thromboembolism, including AF, hypercoaguable state or low ejection fraction, we recommend VKA therapy (target INR 2-3)…low dose aspirin should be considered, particularly in patients with history of atherosclerotic vascular disease. We suggest ASA not be added to long-term VKA therapy in patients with bioprosthetic heart valves who are at particularly high risk of bleeding…” CHEST 2008
Therapeutic Alternatives for Atrial Fibrillation • Aspirin • Aspirin + Clopidogrel • Warfarin • Dabigatran • Rivaroxaban • Apixaban
Clinical Question • In a 74 year old patient who is at high risk of ischemic stroke secondary to atrial fibrillation and bioprosthetic aortic valve replacement, is rivaroxaban as compared to warfarin, effective at reducing stroke risk without increasing risk of bleeding?
ROCKET-AF ROCKET-AF. NEJM 2011;10.1056/NEJMoa1009638
Results: Efficacy ROCKET-AF. NEJM 2011;10.1056/NEJMoa1009638
Results: Safety ROCKET-AF. NEJM 2011;10.1056/NEJMoa1009638
Study Limitations • Methodology: • 1 site violated Good Clinical Practice; when patients excluded, should have re-analyzed distribution of baseline characteristics • Did not specify in detail who collected the results (more potential for bias) • Clinically • patients in this study differs to JF (ie. no prosthetic heart valve) • patients in the study on warfarin were only in the therapeutic range 55% of the time
Assessment of Therapeutic Alternatives for Atrial Fibrillatrion http://www.sparctool.com/ http://www.sparctool.com/
Therapeutic Recommendation and Justification • Do not restart rivaroxaban for stroke prophylaxis • Suggest starting warfarin at a low dose such as 3mg podaily to target INR 2-3 once clinically stable and active bleeding ruled out
Monitoring: Efficacy • S: Ø dizziness, blurred vision, numbness, paralaysis or weakness, fatigue, shortness of breath • O: Ø loss of coordination, slurred speech
Monitoring: Safety • S: Dizziness, fatigue, headache, lethargy, GI upset, abdominal pain, • O: vitals, Hgb, MCV, INR, AST, ALT, rash, urticaria, bruising
Follow-up • August 12: • Discussed pros and cons of warfarin therapy with patient • After learning more about the drug and importance of INR monitoring and interactions, the patient and his family were amenable to trying warfarin again • Initiated warfarin 3mg po daily with daily INRs