What is the treatment for a clot in the atrium?

Medical Treatment for Atrial Thrombus

Therapeutic anticoagulation with warfarin (INR 2.5-3.5) or a direct oral anticoagulant (DOAC) is the definitive treatment for atrial thrombus, with continuation for at least 3-4 weeks followed by repeat imaging to confirm resolution before any cardioversion is attempted. 1

Immediate Management

When atrial thrombus is detected on transesophageal echocardiography (TEE), cardioversion must be postponed and therapeutic anticoagulation initiated immediately. 1

Anticoagulation Regimen

• Start therapeutic anticoagulation with either:

  • Warfarin targeting INR 2.5-3.5 (higher than standard AF anticoagulation) 1
  • Low-molecular-weight heparin (LMWH) or unfractionated heparin at full venous thromboembolism treatment doses as a bridge to oral anticoagulation 1
  • DOACs (apixaban, rivaroxaban, edoxaban, dabigatran) at standard dosing 2, 3

• Continue anticoagulation for 4-12 weeks to allow thrombus resolution or endothelialization 1

Follow-Up Imaging Strategy

Repeat TEE after 4-12 weeks of therapeutic anticoagulation to document thrombus resolution. 1

• If thrombus has resolved: Cardioversion can proceed if indicated, followed by at least 4 weeks of continued anticoagulation 1
• If thrombus persists despite adequate anticoagulation: Do not perform cardioversion; consider switching to a rate control strategy instead of rhythm control 1

Long-Term Anticoagulation Decision

After the initial treatment period, long-term anticoagulation decisions must be based on the CHA₂DS₂-VASc score, not on whether the thrombus resolved or rhythm was restored. 2, 4

• Males with CHA₂DS₂-VASc ≥2 or females with ≥3 require indefinite anticoagulation 2
• Target INR 2.0-3.0 for long-term warfarin therapy 1
• DOACs are preferred over warfarin for long-term management due to lower bleeding risk 2, 4, 3

Critical Pitfalls to Avoid

Never attempt cardioversion when thrombus is present—this dramatically increases stroke risk from embolization. 1

Do not discontinue anticoagulation based on successful thrombus resolution or return to sinus rhythm; the decision must be based solely on stroke risk stratification. 2, 4

Aspirin alone is explicitly contraindicated for stroke prevention in atrial fibrillation with thrombus—it provides inadequate protection. 2, 5

Special Considerations

Left Atrial Appendage Thrombus Specifically

• Left atrial appendage thrombus carries the highest embolic risk and requires the same aggressive anticoagulation approach 1
• Spontaneous echo contrast (smoke) in the left atrium is an independent risk factor for thrombus formation and warrants anticoagulation even without visible thrombus 1

Rheumatic Mitral Valve Disease with Thrombus

• Warfarin (INR 2.5, range 2.0-3.0) is strongly recommended over DOACs in rheumatic valve disease with left atrial thrombus 1

Monitoring During Treatment

• Assess bleeding risk using HAS-BLED score at each visit 1, 3
• High bleeding risk (HAS-BLED ≥3) requires more frequent follow-up but does not automatically contraindicate anticoagulation 2, 4
• Address modifiable bleeding risk factors (uncontrolled hypertension, concurrent NSAIDs, alcohol excess) 1, 3

Anticoagulation Failure

If thrombus does not resolve after 4-12 weeks of therapeutic anticoagulation with documented adequate INR or DOAC adherence, abandon rhythm control strategy and pursue rate control instead. 1