CARDIOVASCULAR JOURNAL OF AFRICA • Volume 33, No 6, November/December 2022 322 AFRICA Review Article A clinical conundrum: review of anticoagulation in pregnant women with mechanical prosthetic heart valves M Jenneker, H Ramnarain, H Sebitloane Abstract In South Africa, maternal mortality from cardiovascular disease remains high. The recent Saving Mothers report 2017–2019 from the Confidential Enquiries into Maternal Deaths revealed that indirect maternal death from medical and surgical disorders is the fourth commonest cause of maternal death, accounting for 16.9% of deaths, with cardiac disease accounting for one-third of this. The burden of rheumatic heart disease (RHD) is a significant contributor to maternal morbidity and mortality. The true burden is unknown due to limited data. The natural history of RHD confers additional risk as many cases may remain undiagnosed, with first presentation occurring during pregnancy. This undiagnosed subset of women may be the result of poor accessibility to healthcare facilities and primary healthcare interventions for acute rheumatic fever. RHD causes progressive damage to the heart valves, especially the left-sided valves, which eventually require surgical correction with mechanical prosthetic valves. Keywords: bio-prosthetic heart valves, mechanical heart valves, pregnancy, warfarin, heparin, rheumatic heart disease Submitted 23/2/22, accepted 28/5/22 Published online 8/9/22 Cardiovasc J Afr 2022; 322–328 www.cvja.co.za DOI: 10.5830/CVJA-2022-028 Anticoagulation in pregnant women with mechanical heart valves involves a delicate balance between maternal and foetal benefit. To date, a paucity of large, randomised, controlled trials in pregnancy, and an abundance of meta-analyses with widespread heterogeneity have provided little guidance and consensus among the experts. In the hope of achieving equipoise, various regimens are reported in the literature. Mechanical heart valves are prone to thromboembolic complications (TEC), which require lifelong anticoagulation to prevent adverse events such as stuck valves, stroke and even death.1-3 The risk of TEC is dependent on the drug and anticoagulation regimen used. The commonest anticoagulants used in the general population are the vitamin K antagonists (VKA).4 In the absence of contra-indications, they remain an effective, cheap, easily administered option for persons with prosthetic valves.4 Herein follows a narrative appraisal of the current body of evidence with recommended guidelines for management in these women. Rheumatic heart disease (RHD) and its sequelae are an important cause of cardiovascular pathology. The prevalence of RHD is unknown due to a paucity of studies and a lack of prospective data.5,6 In sub-Saharan Africa (SSA), RHD contributes to 30% of cardiac disease in pregnancy and it is the commonest cause of valvular heart disease.5-7 RHD is associated with maternal mortality rates of up to 34% and significant foetal loss.5 RHD, although extremely rare in high-income countries, continues to affect marginalised populations because of poor access to healthcare facilities, limited access to primary healthcare prevention strategies for acute rheumatic fever and delays in diagnosis due to a lack of skill on the part of healthcare workers or failure to follow up by those affected.7 RHD causes slow, progressive damage to the heart valves, especially the left-sided valves, which eventually require surgical correction with prosthetic valves. It has been estimated that over 280 000 prosthetic heart valves are replaced worldwide each year, half of which are mechanical.8 The modified World Health Organisation classification of maternal cardiovascular risk places prosthetic valves as category III. These women are therefore at significant risk for maternal morbidity and mortality, with reported rates for maternal adverse events of 19 to 27%. They require a multidisciplinary team approach in an expert centre for pregnancy and cardiac disease.9 Prosthetic heart valves There are two main types of valves, namely mechanical (MHV) and bio-prosthetic valves (BPV).8,10 The type of valve used has to be carefully selected based on various factors such as age, haemodynamic performance, prevention of prosthesis– patient mismatch, durability, implantability, patient preference and a patient’s desire for fertility.10 The American College of Department of Obstetrics and Gynaecology, School of Clinical Medicine, College of Health Sciences, University of KwaZulu-Natal, Durban, South Africa M Jenneker, MB ChB, MMed, FCOG, jennekerm@ukzn.ac.za H Ramnarain, FCOG H Sebitloane, FCOG, PhD Department of Obstetrics and Gynaecology, High Risk Obstetrics, Inkosi Albert Luthuli Central Hospital, Cator Manor, Durban, South Africa M Jenneker, MB ChB, MMed, FCOG H Ramnarain, FCOG
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