What is the recommended anticoagulation therapy, such as warfarin (International Normalized Ratio (INR) management), for patients with non-compaction cardiomyopathy at high risk of thromboembolic events?

Anticoagulation Management in Non-Compaction Cardiomyopathy

Warfarin anticoagulation with a target INR of 2.0-3.0 is indicated for patients with non-compaction cardiomyopathy who have atrial fibrillation, ventricular thrombus, or significant left ventricular dysfunction. 1

Risk Stratification for Anticoagulation in NCCM

Patients with non-compaction cardiomyopathy (NCCM) have a higher risk of thromboembolism than the general population due to several factors:

• Deep intertrabecular recesses causing blood stagnation
• Left ventricular dysfunction
• Higher prevalence of atrial fibrillation (25-30% of adult NCCM patients) 2

Indications for Warfarin Anticoagulation:

1. Definite indications (Class I recommendation):

   • Paroxysmal, persistent, or chronic atrial fibrillation with NCCM 1
   • Documented ventricular thrombus
   • Previous thromboembolic event

2. Consider anticoagulation for:

   • Significant left ventricular systolic dysfunction (EF <35%)
   • Severe left ventricular dilation
   • Evidence of blood stagnation in deep trabeculations

Anticoagulation Protocol

Target INR Range:

• Standard target: 2.0-3.0 for most NCCM patients 1
• Higher target: 2.5-3.5 for patients with:
  • Mechanical prosthetic heart valves 1
  • Recurrent thromboembolism despite therapeutic INR

Monitoring Recommendations:

• Initial frequent monitoring (every 2-3 days) until stable INR
• Once stable, check INR every 4 weeks
• More frequent monitoring with medication changes or illness
• Consider home INR monitoring for selected patients

Special Considerations:

Triple Therapy (Warfarin + Dual Antiplatelet):

If NCCM patient requires triple therapy (e.g., after coronary stenting):

• Lower target INR (2.0-2.5) 3
• Use low-dose aspirin (75-81 mg)
• Minimize duration of triple therapy when possible
• Consider proton pump inhibitor for GI protection

Perioperative Management:

For NCCM patients requiring surgery:

• Assess thromboembolic risk vs. bleeding risk
• For high thromboembolic risk: bridging with LMWH 1
• For low risk: hold warfarin 5 days before procedure
• Resume warfarin 12-24 hours post-procedure if hemostasis is adequate

Pitfalls and Caveats

1. Bleeding risk increases exponentially when INR >5.0 4, requiring prompt intervention:

   • INR 5-9 without bleeding: Hold warfarin, consider oral vitamin K
   • INR >9 or active bleeding: IV vitamin K and prothrombin complex concentrate

2. Subtherapeutic INR management:

   • Approximately 22% of warfarin patients have subtherapeutic INRs when presenting to emergency departments 5
   • Patients with subtherapeutic INR have higher risk of thromboembolism (50% of thromboembolic events occur with subtherapeutic INR) 5
   • Consider bridging with LMWH if persistently subtherapeutic

3. Drug interactions:

   • Many medications affect warfarin metabolism
   • Check for interactions with any new medication
   • Antibiotics, antifungals, and antiseizure medications are common culprits

4. Diet considerations:

   • Counsel patients on consistent vitamin K intake
   • Sudden changes in green vegetable consumption can affect INR

5. Alternative anticoagulants:

   • Direct oral anticoagulants (DOACs) may be considered in selected NCCM patients 6
   • However, warfarin remains the standard as there are limited data on DOACs specifically in NCCM

Pediatric Considerations

For children with NCCM requiring anticoagulation:

• Target INR is also 2.0-3.0 7
• More frequent INR monitoring is typically needed
• Achieving target INR is more challenging in children (mean 48.5% of time in therapeutic range) 7
• Despite lower time in therapeutic range, clinical outcomes can still be acceptable 7

Remember that anticoagulation management in NCCM requires regular monitoring and adjustment to maintain the target INR range while minimizing bleeding complications.