CARDIOVASCULAR JOURNAL OF AFRICA • Volume 33, No 6, November/December 2022 AFRICA 325 Recent data from the ROPAC share a similar sentiment.24,25 They considered the studies to be unclear on whether the adverse events were related to the anticoagulation or not. Also, with increasing pregnancy, the dose of VKA may increase due to the pharmacodynamic changes that occur with advancing pregnancy. It is prudent to note that the safety of first-trimester low-dose VKA < 5 mg remains unconfirmed and requires more study. Therefore, it is imperative that all options, risks and benefits are discussed with the mother. Role of low-dose aspirin Another gap in the literature is the recent advocacy of aspirin (acetylsalicylic acid, ASA) in the second and third trimesters in women with prosthetic valves.32 ROPAC reported only a 6.1% concomitant use of ASA.33 The addition of low-dose ASA after the first trimester is supported by the American College of Clinical Pharmacy, the ACC and AHA.11,32 The data are deficient on the safety and its effect on the mother and foetus. More prospective data are needed to guide the professional bodies. What do the international guidelines say? A review of the latest international guidelines from the American College of Chest Physicians (ACCP), European Society of Cardiology (ESC) and the ACC/AHA revealed the following consensus statements based on expert opinion (Fig. 3). All the experts are in agreement that pregnant women with MHVs are at high risk of morbidity, with maternal mortality rates of > 1%. These risks are commonly associated with poor compliance, inadequate monitoring and incorrect dosing or administration. Women should be counselled adequately and they should understand the inherent risks and benefits to each regimen. The guideline recommendations are based on consensus statements from expert opinion or based on small retrospective studies or registries. Overall data in pregnancy are limited and there is an urgent need for more prospective studies to guide current practice. The authors present the following regimens for anticoagulation in pregnant women with MHV, currently practiced at Inkosi Albert Luthuli Central Hospital (Fig. 4). These regimens are based on the available evidence, recent international guidelines and a long history of clinical experience and management of pregnant women with MHV. Systematic reviews and meta-analysis A recent systematic review and meta-analysis by D’Souza et al. in 2016 reviewed 1 786 published articles, which correlated to MHV Life-long anticoagulation on warfarin 1st missed period/positive pregnancy test IV UFH: intravenous unfractionated heparin, LMWH: low-molecular weight heparin, NVD: normal vaginal delivery, IOL: induction of labour. Monitoring for warfarin = INR (international normalised ratio) = 2.5–3.5; UFH = aPTT (activated partial thromboplastin time) = ratio of 2–2.5 times the control; LMWH = anti-Xa (0.8–1.2 aortic valves) (1–1.2 for right-sided valve and mitral valve). Due to constraints with transport to the hospital and the geographical position of the various drainage areas women are generally admitted at 37 weeks for bridging to IV UFH. Those that present late are bridged at a minimum of 36 hours prior to planned delivery. Reference for mean therapeutic targets: 2018 ESC guidelines for the management of cardiovascular disease during pregnancy doi: 10.1093/ eurheartj/ehy340 At 12 weeks change to warfarin At 36 weeks (on warfarin) bridge back to UFH and plan delivery If elective caesar stop UFH 4–6 hours before planned caesar If NVD/IOL stop UFH once in active labour If elective caesar stop UFH 4–6 hours before planned caesar If NVD/IOL stop UFH once in active labour Less than 6 weeks Change to dose-adjusted LMWH or IV UFH till end of 1st trimester Continue warfarin if < 5 mg (weak evidence) More than 6 weeks (warfarin-exposed foetus) Change to dose-adjusted LMWH Continue warfarin if < 5 mg (weak evidence) At 12 weeks continue doseadjusted LMWH At 37 weeks (on dose-adjusted LMWH) bridge back to UFH and plan delivery Fig. 4. Anticoagulation regimens used in pregnancy at Inkosi Albert Luthuli Central Hospital high-risk unit using warfarin, UFH and LMWH. • Three regimens are recognised: • Use of dose-adjusted LMWH throughout pregnancy using peak anti-Xa levels for monitoring • Use of dose-adjusted subcutaneous heparin throughout pregnancy with mid-interval aPTT to twice the control or anti-Xa of 0.35–0.70 U/ml • Sequential therapy with IV UFH or dose-adjusted LMWH until 13 weeks and switching to a VKA for the rest of pregnancy • All regimens will require bridging to IV UFH at 36 weeks before planned delivery • It advocates the use of add-on low-dose aspirin (ASA) • The use of warfarin throughout in patients at higher risk of thrombosis should be considered. The American College of Chest Physicians 9th edition (ACCP 2012) • In contrast, the ESC does not support the routine use of low-dose aspirin and subcutaneous heparin • They do make distinctions for warfarin dependent on dosing, i.e. women on doses < 5 mg can be counselled to continue warfarin throughout pregnancy because of low risk of embryopathy (< 2%) and foetal loss (< 20%) • This should be done with full consultation with the mother and a shared decision-making approach should be adhered to • Furthermore, the guidelines advocate the strict monitoring of peak and trough levels for anti-Xa in women receiving dose-adjusted LMWH European Cardiology Society 2018 (ESC) • Advocates use of add-on low-dose aspirin • The 2020 ACC/AHA recognises three regimens for anticoagulation: • Low-dose VKA throughout pregnancy • Switch to dose-adjusted LMWH from the first trimester throughout pregnancy • Sequential therapy with switching to dose-adjusted IV UFH or dose-adjusted LMWH from 6–12 weeks • All regimens will require bridging to IV UFH at 36 weeks before planned delivery • These regimens are supported by the ESC as well 2020 American College of Cardiology and American Heart Association (ACC/AHA) Fig. 3. What the international guidelines say.
RkJQdWJsaXNoZXIy NDIzNzc=