Optimum INR intensity and therapeutic INR control in patients with mechanical heart valve prosthesis on warfarin oral anticoagulation at Dr George Mukhari academic hospital: a three-year retrospective study

Abstract

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.

Anticoagulation control, outcomes, and associated factors in long-term-care patients receiving warfarin in Africa: a systematic review

“…The included studies were published between 2006 to 2021. The majority of them (15 out of 18) were conducted using retrospective study designs [ 7 , 23 , 28 – 40 ]. Pre-post intervention [ 41 ] and prospective study designs [ 42 , 43 ] were employed by one and two studies, respectively.…”

“…Pre-post intervention [ 41 ] and prospective study designs [ 42 , 43 ] were employed by one and two studies, respectively. Five studies were conducted in South Africa [ 7 , 28 , 33 , 37 , 38 ], 3 in Ethiopia [ 23 , 31 , 40 ], 2 in Sudan [ 32 , 41 ], 2 in Kenya [ 36 , 42 ], 2 in Tunisia [ 29 , 43 ] and 2 in Botswana [ 39 , 44 ]. One study was included from Namibia [ 35 ] and the remaining one study was conducted both in South Africa and Uganda.…”

“…The smallest and the largest sample size was 21 [ 32 ] and 915 [ 45 ], respectively. In addition, the minimum cohort follow-up period was 4 months [ 46 ], and the maximum was 19 years [ 28 ]. All studies were conducted in outpatient settings (cardiology clinic anticoagulation clinic, INR testing clinic, warfarin clinic, cardiac, hemato-oncology, and cardiothoracic clinics, etc.).…”

“…Bleeding/hemorrhagic events were reported in three studies as both major and minor bleeding events [ 29 , 39 , 43 ], and the remaining studies that documented these events reported either of them. The highest percentage of bleeding incidence [(59%, (9.5% major bleeding, 49.5% minor bleeding)] was reported by studies carried out in Tunisia [ 29 ] and the lowers incidence (0.006% per patient-year) was reported from Dr. George Mukhari Academic Hospital [ 28 ] study in South Africa. During follow-up period, six studies [ 28 , 31 , 37 , 43 , 48 , 49 ] reported that 0.002% per-patient year) [ 43 ] to 22.5% [ 39 ] of the patients developed thromboembolic events.…”

“…The highest percentage of bleeding incidence [(59%, (9.5% major bleeding, 49.5% minor bleeding)] was reported by studies carried out in Tunisia [ 29 ] and the lowers incidence (0.006% per patient-year) was reported from Dr. George Mukhari Academic Hospital [ 28 ] study in South Africa. During follow-up period, six studies [ 28 , 31 , 37 , 43 , 48 , 49 ] reported that 0.002% per-patient year) [ 43 ] to 22.5% [ 39 ] of the patients developed thromboembolic events. Thromboembolic complications/events in range of 1.64 to 7.5% were occurred in four remaining studies [ 29 , 31 , 43 , 50 ].…”