Why is anticoagulation (prevention of blood clot formation) important after Transcatheter Aortic Valve Replacement (TAVR)?

Anticoagulation After TAVR: Essential for Preventing Thrombotic Complications

Anticoagulation after TAVR is crucial to prevent thromboembolism, valve thrombosis, and associated mortality, with the current standard being clopidogrel 75 mg daily for 3-6 months plus lifelong aspirin 75-100 mg daily for patients without other indications for anticoagulation. 1, 2

Rationale for Anticoagulation After TAVR

Anticoagulation after TAVR is necessary for several important reasons:

1. Prevention of valve thrombosis:

   • Subclinical leaflet thrombus formation may be more common after TAVR than previously appreciated 1, 2
   • Patients on vitamin K antagonists show lower rates of reduced leaflet motion compared to those on antiplatelet therapy alone 2

2. Reduction of thromboembolic events:

   • TAVR patients are at higher risk of ischemic stroke and peripheral embolism, particularly in the first 90 days after valve implantation 1
   • A large observational registry demonstrated significantly lower stroke rates in patients treated with vitamin K antagonists (2.69 per 100 person-years) versus those not treated (7.00 per 100 person-years) 1

3. Reduction in cardiovascular mortality:

   • Lower cardiovascular death rates have been observed in patients on vitamin K antagonist therapy (2.08 per 100 person-years) compared to those not on therapy (6.50 per 100 person-years) 1

Current Anticoagulation Recommendations

For patients WITHOUT other indications for anticoagulation:

• Standard approach: Clopidogrel 75 mg daily for 3-6 months plus lifelong aspirin 75-100 mg daily 1, 2

  • 3 months for self-expanding valves
  • 6 months for balloon-expandable valves
  • Class IIb, Level of Evidence C recommendation 1, 2

• Alternative approach: Vitamin K antagonist therapy (INR 2.0-2.5) may be reasonable for the first 3 months after TAVR in patients at low risk of bleeding 2

  • Class IIb, Level of Evidence B-NR recommendation

For patients WITH atrial fibrillation or other indications for anticoagulation:

• Continue anticoagulation as per guidelines for AF in patients with prosthetic heart valves 1
• When using vitamin K antagonist therapy, continuation of aspirin is reasonable, but additional antiplatelet therapy should be avoided due to increased bleeding risk 1, 2

Important Cautions

1. Direct oral anticoagulants (DOACs) are NOT recommended:

   • The FDA specifically warns against using rivaroxaban (Xarelto) in TAVR patients based on the GALILEO study showing higher rates of death and bleeding 3
   • Class III: Harm recommendation for use of oral direct thrombin inhibitors or anti-Xa agents in patients with prosthetic heart valves 2

2. Bleeding risk considerations:

   • Recent meta-analysis data suggests DAPT increases bleeding risk compared to aspirin alone (RR = 1.67,95% CI 1.24 to 2.24) at 6-12 months follow-up, without significant differences in mortality, stroke, or MI 4
   • Consider patient-specific bleeding risk factors when determining therapy duration 2

Monitoring After TAVR

• Echocardiography before discharge to establish new baseline valve function 1
• Repeat echocardiography at 30 days and then at least annually to monitor for complications including valve thrombosis 1
• Regular ECG monitoring for detection of asymptomatic AF and conduction defects 1

Evolving Evidence

While DAPT has been the standard approach based on early TAVR clinical trials, newer evidence suggests:

• Single antiplatelet therapy with aspirin alone may reduce bleeding risk without increasing thromboembolic events 4
• Warfarin has shown similar effectiveness and safety compared to DAPT in retrospective studies 5

However, until more definitive evidence emerges from ongoing trials, the current guideline-recommended approach remains DAPT for 3-6 months followed by lifelong aspirin for patients without other indications for anticoagulation.