Transcatheter mitral valve implantation (TMVI) is a new treatment option for high-risk surgical patients with degenerated bioprosthesis (ViV), failed annuloplasty rings (ViR) and severe mitral annular calcification (ViMAC). However, limited data exist on transcatheter heart valve (THV) thrombosis.

To report the incidence, clinical impact and treatment outcomes of THV thrombosis in patients undergoing TMVI.

All consecutive patients underwent TMVI in our center between July 2010 and September 2019 were included. A transoesophageal echocardiography (TOE) and a computed tomography (CT) were performed at discharge and each follow-up clinical visit (3 months, 1 year and then annually). THV thrombosis was defined as the presence of at least one thickened leaflet with restricted motion confirmed by TOE and/or contrast CT, and was classified according to the timing of diagnosis as immediate (at discharge), early (at the 3-month clinical visit), or late (at the 1-year clinical visit and thereafter) (Table 1).

A total of 132 patients underwent TMVI. At a median follow-up of 1.4 years, THV thrombosis was observed in 16 (12.1%) patients: 7 (43.8%) in the ViV TMVI group, 5 (31.2%) in the ViR group and 4 (25%) in the ViMAC group (P=0.93). In 13 (81.2%) patients, THV thrombosis occured within the first 3 months. Neither stroke nor other thromboembolic event occurred. Rates of early and late THV thrombosis were higher in patients without anticoagulation than in those treated with anticoagulation (respectively 25% vs.3.2%, p=0.018 and 13.6% vs.0%, P=0.023). After optimization of antithrombotic treatment, THV thrombosis resolved in all but one asymptomatic patient (Fig. 1).

THV thrombosis is frequent after TMVI, occurs mainly within the first 3 months, is mostly subclinical and resolves after optimization of antithrombotic treatment. An anticoagulation therapy for at least 3 months after the procedure is mandatory.