Background: Anticoagulation among patients underwent valve replacement with mechanical prosthetic valve is necessary to prevent valve thrombosis and thromboembolism. This study attempts to determine the predictors of outcome of patients with mechanical prosthetic valves treated with warfarin and subset of patients taking Aspirin.
Method: A prospective cohort study, which includes adult patients with mechanical prosthetic valve at the Philippine Heart Center, who has been receiving oral warfarin for their anticoagulation with their Prothrombin time - INR (target range) monitored periodically on follow up. Patients were followed up if there is optimal anticoagulation, thromboembolism and bleeding episodes.
Results: A total of 130 patients were included in the study, 74 were males, while 56 were females. The mean age was 43 years old, majority of the patients were diagnosed with rheumatic heart disease (78%) and 38 patients (29%) had double mechanical prosthetic valve postion. Ninety-two patients (71%) were on optimal anticoagulation with an INR of 2-3. Eleven patients (8%) had bleeding with a mean INR level of 4.88 ± 3.3 while 6 patients (4.6%) had thromboembolism with a mean INR level of 1.69 ± .37. Among patients who were taking aspirin concomitantly with warfarin, the outcomes for thromboembolism and bleeding predictors were not statistically significant. Diagnosis of rheumatic heart disease shows a trend in favor for bleeding with a p value of 0.045.
Conclusion: The study showed a low incidence of bleeding and thromboembolism among Filipino patients ages 33 to 57 years old with mechanical prosthetic valve treated with warfarin and among subset of patients taking aspirin. Optimal anticoagulation is still the most important predictor of outcome. Risk assessment for each patient must be individualized with careful appraisal of the risk-benefit profile.