Early versus later restart of blood thinners after surgery for chronic subdural hematoma in people with atrial fibrillation

Restarting Early Versus Later Anticoagulation for Chronic Subdural Hematoma With Atrial Fibrillation (RELACS): An International Multicenter, Randomized Controlled, Two-arm, Assessor-blinded, Trial

Not applicable Interventional Helsinki University Central Hospital · NCT06696079

This trial will test whether restarting oral blood thinners 5 days versus 30 days after surgery is safer and better at preventing clots for adults with atrial fibrillation who had surgery for chronic subdural hematoma.

Quick facts

PhaseNot applicable
Study typeInterventional
Enrollment332 (estimated)
Ages18 Years and up
SexAll
SponsorHelsinki University Central Hospital Academic / other
Locations6 sites (Oulu, North Ostrobothnia and 5 other locations)
Trial IDNCT06696079 on ClinicalTrials.gov

What this trial studies

This randomized trial assigns adults with atrial fibrillation who undergo burr-hole evacuation for symptomatic chronic subdural hematoma to resume their oral anticoagulant either 5 days or 30 days after surgery. Participants are followed for three months to record thromboembolic events, bleeding complications, need for reoperation, functional outcomes, mortality, and healthcare use. The study uses standard clinical management apart from the timing of anticoagulation resumption and analyzes outcomes between the two groups. Results aim to clarify whether earlier anticoagulation reduces clot-related events without increasing harm.

Who should consider this trial

Good fit: Adults (≥18) with known spontaneous atrial fibrillation who were on an oral anticoagulant and underwent burr-hole evacuation with drainage for symptomatic chronic subdural hematoma, with randomization within 4 days of surgery, are ideal candidates.

Not a fit: Patients with intraoperative or immediate postoperative hemorrhagic complications, those requiring craniotomy or other non–burr-hole surgery, recent prior CSDH surgery within 12 months, cerebrospinal fluid shunts, CSDH within an arachnoid cyst, or whose hematoma is found to be a hygroma are unlikely to be eligible or to benefit from this protocol.

Why it matters

Potential benefit: If successful, earlier resumption could reduce strokes and other clotting events after surgery without increasing bleeding or reoperation, improving recovery and reducing healthcare use.

How similar studies have performed: Observational studies and retrospective series have suggested timing of anticoagulation influences outcomes, but randomized evidence specific to chronic subdural hematoma is limited and results have been mixed.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

* Age ≥18 years.
* Patients with a symptomatic unilateral or bilateral CSDH requiring burr-hole evacuation with drainage (CSDH is predominantly hypodense or isodense on imaging \[CT/MRI\]; clinical symptoms attributable to the CSDH; patients with bilaterally operated CSDHs will be treated with the same protocol on both sides and analyzed as a single study participant).
* Patients that are on an oral anticoagulation medication due to permanent, persistent or paroxysmal spontaneous atrial fibrillation previously known
* Randomization done within 4 days of the surgery

Exclusion Criteria:

* Intraoperative or immediate postoperative hemorrhagic complication
* CSDH requiring surgical treatment other than burr-hole evacuation (e.g. craniotomy)
* Prior CSDH surgery within 12 months
* Cerebrospinal fluid shunt
* CSDH is in an arachnoid cyst
* If the operated hematoma is revealed to be a cerebrospinal fluid collection (hygroma)
* Conditions other than atrial fibrillation that require anticoagulation, including therapeutical dose of low molecular-weight heparin or heparin (for example, pulmonary embolism, deep vein thrombosis, hypercoagulability syndromes)
* Mechanical heart valve(s)
* Moderate or severe mitral stenosis (other valvular diseases and biological valves are eligible)
* Contraindication to anticoagulation medication (for example bleeding disorder, documented high risk of fall \[e.g. due to severe alcoholism\], severe thrombocytopenia, severe anemia)
* Concomitant use of antiplatelet medication
* Moderate to severe renal insufficiency (creatinine clearance \<30 ml/min or on dialysis)
* Not a permanent resident in Finland (for Finnish patients) or not a permanent resident in Region Stockholm (for Swedish patients)

Where this trial is running

Oulu, North Ostrobothnia and 5 other locations

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions Chronic Subdural HematomaAtrial Fibrillationchronic subdural hematomaatrial fibrillationoral anticoagulationwarfarindirect oral anticoagulantssurgery
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.