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infrequent, should be carefully ruled out, especially in patients with small and hypertrophic ventricles.904

14.4.2 Non-structural valve dysfunction

14.4.2.1. Prosthesis–patient mismatch Prosthesis–patient mismatch should be prevented whenever possible after either transcatheter or surgical valve-replacement procedures (see Section 8.5.1.2). When occurring in the aortic position, severe PPM is associated with decreased quality of life, increased rate of rehospitalization and reintervention, and possible reduction in long-term survival, although findings are not consistent throughout all studies.454,905–909 Moderate PPM is more common, but seems to have a limited impact on outcomes. The projected indexed EOA may be predicted prior to valve implantation to avoid severe PPM,908 although this concept has been challenged.910 Less is known about the prevalence and consequences of PPM in the mitral and tricuspid positions, and established definitions are lacking. Prosthesis–patient mismatch is an infrequent indication for reintervention. However, reoperation should be considered in symptomatic patients with severe PPM, particularly if the patient is low risk.394,437,438

14.4.2.2 Paravalvular leak and haemolysis

The diagnosis of PVL requires systematic TOE, because TTE may be inconclusive. Haemolytic anaemia can often be detected in patients with prosthetic valves and is best assessed by measuring lactate dehydrogenase and haptoglobin serum levels, but rarely leads to symptoms. Intervention is needed if a PVL causes haemolysis requiring blood transfusions or symptoms, or if secondary to valve endocarditis. Transcatheter PVL closure is a valid alternative to surgery in the case of significant regurgitation or haemolysis, if feasible depending on the size and location of the leak, but requires specific expertise and planning. Care must be taken not to interfere with mechanical leaflet motion in MHV patients. Reported results for transcatheter PVL closure are inconsistent, with several patients returning with recurrent PVL and/or haemolysis.911 When surgery or transcatheter intervention are contraindicated, medical therapy aims to counteract the effect of haemolysis (iron supplementation and erythropoietin) or reduce it (beta-blockers).912

14.4.3 Endocarditis

Antibiotic prophylaxis is recommended in all patients with a prosthetic valve (including transcatheter valve prostheses) and after valve repair using prosthetic material or with previous episode(s) of infective endocarditis, and should also be considered after transcatheter MV or TV repair.5 It is recommended in such patients when undergoing dental extractions, oral surgery, or other procedures requiring manipulation of the gingival or peri-apical region of the teeth. Particular attention to dental and cutaneous hygiene, and strict aseptic measures during any invasive procedure, are also advised in this population. Additional details on endocarditis prophylaxis are mentioned in the 2023 ESC Guidelines for the management of endocarditis.5 14.4.4 Valve thrombosis

Valve thrombosis occurs mainly in MHVs,913,914 but can also be observed in BHVs.915,916 The spectrum of BHV thrombosis ranges from incidental CCT findings, such as hypo-attenuated leaflet thickening (HALT) with or without reduced leaflet motion but normal gradients, to clinically apparent presentations with elevated gradients, symptoms of valve obstruction, or thromboembolic events.917–919

14.4.4.1 Hypo-attenuated leaflet thickening

Hypo-attenuated leaflet thickening is detected by CCT in 10%–30% of aortic BHVs depending on antithrombotic management, the definition of HALT, the timepoint of assessment, and the type of valve.917,919–921 The significance and clinical implications of these findings with respect to thromboembolic risk and valve durability remain uncertain. Accordingly, routine use of CCT to detect HALT is not indicated.918–920 In patients with relevant increases in gradients, in whom HALT and restricted leaflet motion is confirmed by CCT, elective use of DOACs or VKAs should be considered to resolve leaflet thrombosis.918,921,922

14.4.4.2 Clinically significant valve thrombosis

Obstructive valve thrombosis should be suspected in any patient with any type of prosthetic valve who presents with new-onset dyspnoea or HF symptoms, an embolic event, or an unexpected increase in transvalvular gradients. If TTE findings are uncertain, the diagnosis should be confirmed by TOE and/or CCT to distinguish between thrombus, pannus, and degeneration.923–925 Cinefluoroscopy can detect impaired MHV leaflet motion and reduced opening angles. Adequate anticoagulation must be promptly restored in all patients with MHV thrombosis and subtherapeutic INR. Although surgery remains the first-line option in critically ill patients, emergency valve replacement is associated with increased risk, whereas bleeding and systemic embolism are increased with fibrinolysis.926–928 Slow, lowdose infusion appears to lower complication rates, while preserving thrombolytic success rates.928–931a It is recommended that the decision between surgery and fibrinolysis is taken within the Heart Team, and individualized by weighing clinical factors and local expertise (Figure 20). Management of non-obstructive thrombosis or obstructive thrombosis of an MHV without pronounced HF symptoms depends mainly on the occurrence of a thromboembolic event and the size of the thrombus. Surgery should be considered for a large (>10 mm) non-obstructive prosthetic valve thrombus that is complicated by embolism or persists despite optimal OAC.913,932,933 Anticoagulation using a VKA is the first-line treatment for clinically relevant BHV thrombosis, unless urgent reintervention or fibrinolysis is required due to progressive acute HF or haemodynamic instability.934–938 Because clinically relevant BHV thrombosis is associated with recurrence and may contribute to prosthetic degeneration, indefinite anticoagulation may be considered after a confirmed episode, but this strategy must be balanced against the risk of bleeding.936,939 Downloaded from academic.oup.com/eurheartj/article/46/44/4635/8234488 by guest on 07 October 2026