SAFE-HEART is a single-centre, randomized controlled trial comparing the safety and efficiency of Apixaban versus Warfarin in the early period (3 months) after repair or bioprosthetics of the mitral and aortic valve cardiac surgery in patients with atrial fibrillation requiring oral anticoagulation.

Oral anticoagulation with vitamin K antagonists (VKAs) is currently recommended for 3 months following surgical reconstruction or bioprosthetic replacement of the mitral and aortic valves, regardless of rhythm status.

Despite their effectiveness, the use of warfarin is limited by its narrow therapeutic index, which requires frequent international normalized ratio (INR) measurements to ensure adequate anticoagulation levels. This key limitation leads to failure to maintain target INR levels and treatment discontinuation. Additionally, in the first 3 months after heart surgery, the duration of the therapeutic period is short, even with careful monitoring by experienced physicians.

Over the past decade, direct oral anticoagulants (DOACs)-factor Xa or thrombin inhibitors-have gained widespread use in anticoagulant therapy. It has been demonstrated that DOAC treatment in patients with atrial fibrillation reduces the risk of stroke or systemic embolism and carries a similar risk of major bleeding compared to VKAs during long-term follow-up in patients with atrial fibrillation. Moreover, they offer rapid onset of action, fixed dosing, no need for laboratory monitoring, and minimal interactions with food and other medications. In the postoperative period, DOAC use may also shorten hospital stays and reduce costs.

However, the safety of DOACs in the first months after surgical valve correction (reconstruction/bioprosthetic replacement of the mitral and aortic valves) remains uncertain, which is reflected in the recommendation classes for anticoagulant therapy following these procedures.

The purpose of this study is to establish whether Apixaban is as safe and effective as Warfarin in the first 3 months after reconstruction or bioprosthetics of the mitral and aortic valvescardiac surgery in patients with atrial fibrillation requiring oral anticoagulation.

Inclusion Criteria:

• Age ≥18 years at the time of enrolment
• Open heart aortic or mitral valve repair or biological valve replacement in the last 10 days
• Atrial fibrillation requiring anticoagulation (including pre-existing or post-operative atrial fibrillation),
• Informed consent from either the patient or a substitute decision-maker.

Exclusion Criteria:

• Mechanical valve replacement
• Antiphospholipid syndrome (triple positive)
• Severe renal failure (Cockcroft-Gault equation; creatinine clearance <15 ml/min)
• Known significant liver disease (Child-Pugh classification B and C)
• Left ventricular thrombus
• Ongoing bleeding, hemorrhagic disorders, or bleeding diathesis
• Known contraindication for any DOAC or VKA
• Women who are pregnant, breastfeeding, or of childbearing potential
• Follow-up not possible