Pregnancy with a prosthetic heart valve, thrombosis, and bleeding: the ESC EORP Registry of Pregnancy and Cardiac disease III.

Pregnancy in women with a prosthetic heart valve is considered high risk, primarily due to the need for effective anticoagulation. However, data on the relationship between anticoagulation practices and pregnancy outcomes are very limited. The Registry of Pregnancy and Cardiac disease is a global registry that prospectively enrolled pregnancies in women with a prosthetic heart valve between January 2018 and April 2023. Detailed data on anticoagulation, including dosage and monitoring, and cardiovascular, pregnancy, and perinatal outcomes were collected. In total, 613 pregnancies were included of which 411 pregnancies were in women with a mechanical valve and 202 were in women with a biological valve. The chance of an uncomplicated pregnancy with a live birth in women with a mechanical valve was 54%, compared with 79% in women with a biological valve (P < .001). Thromboembolic and haemorrhagic complications most frequently occurred when low-molecular weight heparin (LMWH)-based regimens were used. Valve thrombosis occurred in 24 (6%) women, and a prosthetic valve in mitral position was associated with valve thrombosis (odds ratio 3.3; 95% confidence interval 1.9-8.0). A thromboembolic event occurred in 12 (10%) women with anti-Xa monitoring and in 9 (21%) women without (P = .060). Foetal death occurred in 20% of all pregnancies. More favourable outcomes were found in women with a biological valve compared with a mechanical valve. In women with a mechanical valve, the use of LMWH was associated with an increased risk of thromboembolic complications. A mitral prosthetic valve was identified as a predictor for valve thrombosis. The benefit could not be confirmed nor refuted, in terms of reduced thromboembolic events, from using anti-Xa level monitoring in women on LMWH.