PB1546 - Time is everything: case report of an acute thrombosis of mechanical aortic valve prosthesis in a pregnant woman

Background: Pregnancy presents a unique challenge for women with mechanical heart valves (MHV), due to the increased incidence of thromboembolic events. Despite being essential, the optimal therapeutic anticoagulation regimen is still unknown as there are several fetal and maternal risks involved.

Aims: To present a difficult-to-manage case of an acute thrombosis of mechanical aortic valve (MAV) prothesis in a pregnant woman.

Methods: Case of a pregnant female with MAV thrombosis while on therapeutic anticoagulation.

Results: A 38-year-old pregnant woman at 22 weeks of gestation presented with acute pulmonary oedema and rapidly progressing to respiratory failure in need of invasive mechanical ventilation. The patient had a history of MAV replacement at age 14 due to severe congenital aortic insufficiency. Since the 5th week of gestation, she was on therapeutic low molecular weight heparin (LMWH) with monthly anti-Xa monitoring (target 0.5-1.0UI/mL).
Transesophageal echocardiogram showed an intra and periprosthetic thrombus with high transvalvular gradient and leaflet limited mobility. The patient began intravenous continuous infusion of unfractionated heparin(UFH) and performed thrombolysis with low-dose ultra-slow infusion of alteplase, with restoration of normal valve function within 3 days. After extubation, she presented mild dysarthria and central facial paralysis (NIHSS 2). MRI exhibited a left frontal opercular lesion. After careful consideration, it was decided to maintain UFH while monitoring neurologic deficits.
The patient showed favorable clinical outcome and, after multidisciplinary discussion, switched to LMWH (1.5mg/kg, twice daily). Initially with daily anti-Xa monitoring, biweekly later on, to achieve a higher target (0.8-1.2UI/mL).
At 35th week of pregnancy, a cesarean section with temporary occlusion of internal iliac arteries with balloon catheter was perfomed, with no complications. The patient was discharged on warfarin.

Conclusion(s): The management of anticoagulation in pregnant woman with MHV is challenging, especially when valve thrombosis occurs. A careful and correct anticoagulation monitoring associated with multidisciplinary approach are crucial to optimal outcomes.