Warfarin is the standard anticoagulant used for patients with mechanical heart valves; however, its use is complicated by a narrow therapeutic window, frequent drug and dietary interactions, and the need for regular international normalized ratio (INR) monitoring. In resource-limited settings such as Pakistan, many patients have difficulty accessing reliable INR testing, which can result in suboptimal anticoagulation and increased risks of thromboembolic or bleeding complications.

Rivaroxaban, a direct oral factor Xa inhibitor, offers predictable pharmacokinetics and does not require routine laboratory monitoring, making it a potentially more convenient option for patients with limited access to INR testing.

This prospective comparative study aims to evaluate rivaroxaban as an alternative to warfarin in patients with mechanical heart valves. Sixty adult patients will be enrolled and followed for one year, comparing the incidence of thromboembolic and bleeding events between patients treated with rivaroxaban and those maintained on dose-adjusted warfarin.

Patients with mechanical heart valves require lifelong anticoagulation to prevent thromboembolic complications such as prosthetic valve thrombosis and systemic embolism. For decades, vitamin K antagonists, particularly warfarin, have been the standard therapy for this population. Warfarin remains the standard anticoagulant therapy for patients with mechanical heart valve replacements, while the use of rivaroxaban in this population is still under investigation.While effective, warfarin therapy presents several challenges, including a narrow therapeutic window, variable dose response, numerous drug-drug and drug-food interactions, and the requirement for regular monitoring of the international normalized ratio (INR). Maintaining therapeutic anticoagulation can therefore be difficult, and both under- and over-anticoagulation may lead to serious complications such as thromboembolism or major bleeding.

These challenges are particularly pronounced in low- and middle-income countries, including Pakistan, where access to reliable and frequent INR testing may be limited. Many patients receiving mechanical valve replacements travel long distances to tertiary care centers for follow-up and may rely on local healthcare providers who do not have access to standardized coagulation monitoring facilities. As a result, inadequate INR monitoring can lead to poorly controlled anticoagulation and increased rates of prosthetic valve complications requiring emergency intervention.

Direct oral anticoagulants (DOACs) have emerged as an important alternative to vitamin K antagonists in several thromboembolic conditions. Rivaroxaban, a direct factor Xa inhibitor, has predictable pharmacokinetics, rapid onset of action, and fewer dietary and drug interactions compared with warfarin. Importantly, rivaroxaban does not require routine laboratory monitoring, which may make it particularly advantageous in settings where access to INR testing is limited. Rivaroxaban has demonstrated efficacy and safety in large clinical trials for the treatment and prevention of venous thromboembolism and for stroke prevention in non-valvular atrial fibrillation.

However, the use of DOACs in patients with mechanical heart valves remains an area of ongoing investigation. Limited early clinical studies and experimental models have suggested that factor Xa inhibition may provide effective anticoagulation in the thrombogenic environment associated with mechanical prosthetic valves. Preclinical studies using animal models have demonstrated reduced thrombus formation and platelet deposition with rivaroxaban, supporting the biological plausibility of this approach. Small pilot clinical investigations have also explored the feasibility of rivaroxaban in selected patients with mechanical valves, although evidence remains limited and further clinical evaluation is required.

Rawalpindi Institute of Cardiology is a tertiary cardiac center where a large number of patients undergo mechanical valve replacement each year. Many of these patients experience difficulty maintaining stable anticoagulation with warfarin because of limited access to INR monitoring, socioeconomic constraints, or complications related to warfarin therapy. These challenges provide a strong clinical rationale for exploring alternative anticoagulation strategies that may be more practical for patients in resource-limited settings.

This prospective comparative study is designed to evaluate rivaroxaban as a potential alternative anticoagulant in patients with mechanical heart valves who experience difficulty with conventional warfarin therapy. Patients receiving rivaroxaban will be followed and compared with a control group of patients continuing standard dose-adjusted warfarin therapy. Participants will be monitored over a one-year follow-up period to evaluate the incidence of thromboembolic and bleeding events, as well as overall treatment safety.

Clinical follow-up will include regular patient assessments and echocardiographic evaluation to monitor prosthetic valve function and detect potential thrombotic complications. Safety monitoring will include evaluation for bleeding events, thromboembolic complications, and other adverse outcomes during the follow-up period.

By comparing clinical outcomes between rivaroxaban and warfarin therapy in patients with mechanical heart valves, this study aims to generate preliminary evidence regarding the feasibility and safety of factor Xa inhibition in this high-risk population. If rivaroxaban demonstrates comparable clinical outcomes, it may represent a more convenient and accessible anticoagulation strategy for patients who face significant barriers to regular INR monitoring in resource-limited healthcare environments.

Inclusion Criteria:

• Adult patients (≥18 years) with mechanical heart valves
• History of thromboembolic or bleeding complications while on warfarin or limited access to INR testing
• Ability and willingness to provide informed consent

Exclusion Criteria:

• Contraindication to rivaroxaban
• Hemorrhagic stroke or ischemic stroke within the past 3 months
• Severe renal impairment (creatinine clearance <30 mL/min)
• Increased risk of bleeding due to congenital or acquired disorders