Key result
Warfarin oral anticoagulation in black South African patients with mechanical heart valves achieved an inadequate time in therapeutic range of 49.7%, compared to the ideal of ≥70%.
Why the study?
What are the optimal PT-INR target ranges and the quality of warfarin anticoagulation in black South African patients with mechanical heart valve prostheses?
Observational (n=95)
No
What are the optimal PT-INR target ranges and the quality of warfarin anticoagulation in black South African patients with mechanical heart valve prostheses?
Standard Caucasian-based PT-INR target ranges for mechanical heart valves are applicable to black South African patients, though therapeutic control in this cohort was inadequate.
Inadequate TTR signals poor warfarin control in this cohort; leaves open whether targeted strategies improve outcomes in black South African patients.
Background: Available evidence suggest that the optimum prothrombin time-international normalised ratio (PT-INR) intensities recommended for anticoagulation of patients with mechanical heart valve prosthesis may not apply to all race groups. Optimal PT-INR target ranges and effectiveness of warfarin oral anticoagulation were determined among black South African patients fitted with St Jude bileaflet mechanical heart valve prosthesis (SJBMHVP) at Dr George Mukhari Academic Hospital (DGMAH).Methods: A convenience sample of 95 medical records of patients fitted with SJBMHVP from 1994 until 2013 was reviewed. Optimum PT-INR target ranges were estimated using two different methods: the classical two PT-INR target level method and the alternative, PT-INR specific incident rate method. The quality of warfarin anticoagulation was assessed using the fraction in therapeutic range method.Results: Optimum PT-INR target ranges for all participants fitted with SJBMHVP in the aortic position was estimated to be 2.0–3.5 and 2.6–3.5, respectively, by the classical and alternative methods. That of the patients with mitral valve replacement was estimated to be in the range 2.6–3.5 by the classical method and that of patients with double heart valve replacement was estimated to be < 3.5 by both methods. The quality of warfarin anticoagulation of participants with SJBMHVP replacement was found to be inadequate as indicated by percentage time in treatment range (TTR) of 49.7% for all study participants compared with the ideal TTR of 70% and above.Conclusion: Optimum Caucasian-based PT-INR intensities recommended for oral anticoagulation of patients fitted with mechanical heart valve prosthesis are applicable to black patients fitted with SJBMHVP at DGMAH.
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Ntlokotsi et al. (2018) conducted an observational in Mechanical heart valve prosthesis (n=95). Warfarin oral anticoagulation vs. Ideal TTR ≥70% was evaluated on Percentage time in treatment range (TTR). Warfarin oral anticoagulation in black South African patients with mechanical heart valves achieved an inadequate time in therapeutic range of 49.7%, compared to the ideal of ≥70%.
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