What is the recommended anticoagulation and antiplatelet therapy regimen for a patient with a history of Coronary Artery Bypass Grafting (CABG) with a drug-eluting stent and a mechanical valve?

Anticoagulation and Antiplatelet Therapy for Patients with CABG, Drug-Eluting Stent, and Mechanical Valve

For patients with both a history of CABG with drug-eluting stent and a mechanical valve, the recommended regimen is a vitamin K antagonist (VKA) with a target INR of 2.0-2.5 plus clopidogrel 75 mg daily for up to 12 months after stent placement, followed by VKA monotherapy. 1

Antithrombotic Strategy Algorithm

Initial Assessment:

1. Time since DES implantation:

   • <1 month: Highest risk period for stent thrombosis
   • 1-6 months: Moderate risk

   • 6-12 months: Lower risk

   • 12 months: Lowest risk

2. Mechanical valve considerations:

   • Type of valve (aortic vs. mitral)
   • Additional risk factors for thromboembolism

Recommended Regimen:

First 1-6 months after DES implantation:

• Triple therapy (if bleeding risk is acceptable):

  • VKA (target INR 2.0-2.5)
  • Aspirin 75-100 mg daily
  • Clopidogrel 75 mg daily

• Duration of triple therapy should be minimized to reduce bleeding risk:

  • 1 month is recommended for most patients 1
  • Up to 6 months may be considered in patients at high ischemic risk due to ACS or other anatomical/procedural characteristics that outweigh bleeding risk 1

After triple therapy period until 12 months post-stent:

• Dual therapy:
  • VKA (target INR 2.0-2.5)
  • Clopidogrel 75 mg daily (preferred over aspirin in patients with mechanical valves) 1

Beyond 12 months post-stent:

• VKA monotherapy:
  • Target INR 2.5-3.5 for mechanical mitral valves
  • Target INR 2.0-3.0 for mechanical aortic valves 1

Key Considerations and Caveats

Bleeding Risk Management:

• Use proton pump inhibitors routinely during triple therapy 1
• Maintain INR in the lower part of the therapeutic range (2.0-2.5) during combination therapy 1
• Consider using radial access for any future coronary interventions to reduce bleeding risk 1

Important Contraindications:

• Prasugrel and ticagrelor are not recommended as part of triple antithrombotic therapy due to excessive bleeding risk 1
• Direct oral anticoagulants (DOACs) such as dabigatran are contraindicated in patients with mechanical valves 1
• Anti-Xa inhibitors (rivaroxaban, apixaban, edoxaban) have not been assessed and are not recommended for mechanical valves 1

Special Considerations:

• For On-X mechanical aortic valves specifically, a lower INR target (1.5-2.0) may be considered after 3 months, but DAPT alone without anticoagulation is associated with excess thromboembolic events and should be avoided 2
• If the patient has atrial fibrillation in addition to the mechanical valve, the mechanical valve indication for anticoagulation takes precedence for determining INR targets

Monitoring Recommendations

• Regular INR monitoring to maintain target range
• Clinical assessment for signs of bleeding or thrombotic complications
• Vigilance for stent thrombosis symptoms (chest pain, dyspnea) especially during the first year
• Annual echocardiography to assess valve function

This approach balances the competing risks of stent thrombosis, valve thrombosis, and bleeding complications in this challenging patient population. The strategy prioritizes prevention of potentially fatal valve thrombosis and stent thrombosis while minimizing the risk of serious bleeding events.