Optimum INR in patients with prosthetic heart valve replacement

Objective: Despite various innovations, there is no ideal prosthetic heart valve; thus, patients with prosthetic heart valves still require anticoagulation therapy. This is a retrospective study to identify the optimum warfarin dose and international normalized ratio (INR) in Indian patients with prosthetic heart valves. Methods: All patients who had prosthetic heart valves from September 2013 to February 2014 at the Madras Medical Mission, Chennai, were reviewed. Patient’s data from the institution computer archive and case notes were imputed into Excel worksheet for data analysis. Results: One hundred and twenty-one Indian patients had prosthetic heart valves during this period, the mean age was 44.94 ± 15.70 (years) and mean body surface area was 1.59 ± 0.19 (kg/m2). The male/female ratio was 1:1.2. Seventy-seven patients had mechanical valves whilst 44 had tissue valves. St. Jude Medical bileafet valve was the commonest mechanical valve used. Warfarin was the only anticoagulant used in all patients. Amongst the mechanical valve group, the mean warfarin dose was 4.9 ± 1.87 (mg) and mean INR was 2.16 ± 0.60. In patients with tissue valves, the mean warfarin dose was 3.77 ± 1.74 and mean INR was 2.3 ± 0.68. There was no significant difference in the INR of patients with mechanical valves and atrial fibrillation and those without atrial fibrillation. Warfarin was however discontinued at 3 months for patients with tissue valves. Five (4.13 %) patients died perioperatively. Haemorrhagic complications occurred in 5.2 %, noticed when INR was >3 whilst thrombotic complications occurred in 2.6 % of patients (INR < 1.5) in the mechanical valve group Conclusion: Oral anticoagulants in Indian patients with mechanic heart valves can be maintained safely at a lower INR (1.56–2.76) as against the standard ranges in the guidelines by the American College of Chest Physicians.