Maternal and fetal outcomes in pregnant women with mechanical heart valves: A tertiary center experience

Objective: Patients with mechanical heart valves require lifelong anticoagulation to prevent thromboembolic complications. Pregnancy induces a hypercoagulable state, increasing the risk of those events. Although guidelines recommend anticoagulation with vitamin K antagonists (VKA), recent practice involves replacing VKA with low-molecular weight heparin (LMWH) to reduce fetal complications with an increase in maternal complications. This study aims to analyze outcomes in pregnant patients with mechanical heart valves anticoagulated with VKA or LMWH. Methods: This was a retrospective case series of pregnant patients with mechanical heart valves referred to our tertiary care center from 2008 to 2024. Primary maternal outcomes were mortality and thromboembolic complications. Secondary outcomes were antepartum bleeding, cardiac events (arrhythmias, heart failure, non-thrombotic valvular dysfunction), postpartum hemorrhage. Fetal outcomes included live births and anticoagulant-related fetal anomalies, fetal intracranial bleeding, small for gestational age. Results: Among the eleven patients included based on chart review, four (36 %) received VKAperi-conceptionally and LMWH during pregnancy, three (27 %) received VKA throughout pregnancy, three (27 %) started LMWH preconceptionally and one (9 %) received LMWH in the first trimester and switched to VKA at 14 weeks (sequential regimen). Thromboembolic complications occurred in two patients receiving LMWH: one experienced valvular thrombosis and one non-valvular thrombosis. Seven pregnancies resulted in live births, three in termination of pregnancy and one ended in missed abortion. One fetal subdural hematoma occurred in a patient on sequential therapy at 26 weeks of pregnancy. No other major fetal anomalies related to anticoagulants were reported. Conclusions: Our findings align with existing literature, indicating a higher incidence of maternal complications in women with mechanical heart valves receiving LMWH. Limited data on patients treated with VKA during pregnancy preclude definitive conclusions regarding its safety.