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............................................................................... In a nationwide observational study, patients aged 45 to 54 with surgical aortic BHV implantation and those aged 40 to 70 years with surgical mitral BHV implantation had a significantly higher 15-year mortality than those with a mechanical heart valve (MHV). An analysis of patients 55 to 64 years of age showed no difference in mortality between aortic BHV and MHV prosthesis.462 However, an earlier systematic review463 and a recent meta-analysis464 of studies comparing aortic MHVs and BHVs showed a significant mortality reduction with MHVs in patients <_60 and in those 5070 years of age, respectively. All these studies are limited by their predominantly observational nature and missing information on the type of prostheses implanted. There is no new high-quality evidence supporting a decrease in the established age cut-off for prosthesis selection.

The best aortic valve substitute for younger adults remains unclear. In appropriately selected patients, replacement of the aortic valve using an autograft may be performed, with long-term survival rates and valve-related reoperation that are comparable to those achieved with a MHV, but high expertise in aortic root surgery is required.465 Strategies for patients with small aortic annulus include root enlargement and use of stentless valves. Although the use of sutureless and rapid-deployment aortic valves may reduce invasiveness, cross-clamp and cardiopulmonary bypass times, and potentially lower perioperative complications of SAVR, there is a lack of a largescale randomized comparison on both short- and long-term safety, efficacy, and haemodynamic performance of this approach against conventional aortic valve replacement, which remains the gold standard of procedure.

11.2 Baseline assessment and follow-up

All patients with prosthetic valves require lifelong follow-up to detect early deterioration in prosthetic function or ventricular function, or progressive disease of another heart valve.314 Clinical assessment should be performed yearly or as soon as possible if new cardiac symptoms occur. TTE should be performed if any new symptoms occur or if complications are suspected. After transcatheter, as well as surgical implantation of a BHV, echocardiography, including measurement of transprosthetic gradients, should be performed within 30 days after valve implantation (i.e. baseline), at 1 year, and annually thereafter.470 TOE should be considered if TTE is of poor quality and in all cases of suspected prosthetic dysfunction (especially if the prosthesis is in the mitral position) or endocarditis.314,471 Cinefluoroscopy for MHVs and CCT scanning provide useful additional information if valve thrombus or pannus are suspected to impair valve function.314

11.3 Antithrombotic management

11.3.1 Mechanical prostheses 11.3.1.1 Postoperative anticoagulation management MHVs require lifelong treatment with VKA guided by the INR.472,473 NOACs currently have no role in patients with MHVs.474 Treatment with VKA should be started on the first postoperative day in combination with bridging therapy [with therapeutic doses of either unfractionated heparin (UFH) or off-label use of low-molecular-weight heparin (LMWH)] until therapeutic INR is achieved.475 Similar safety and efficacy outcomes have been reported following bridging with either UFH or LMWH.476 Once a stable therapeutic INR is reached for >_24 h, bridging can be discontinued. The postoperative risk of thromboembolism peaks about 1 month after implantation, but risks are substantially increased up to 6 months.477,478 Long-term prevention of valve thrombosis and thromboembolism after MHV implantation involves effective antithrombotic medication and risk factor modification for thromboembolism.479

11.3.1.2 Target international normalized ratio Target INR should be based upon prosthesis thrombogenicity and patient-related risk factors (Table 10).479 It is recommended to target a median INR value rather than a range to avoid considering extreme values in the target range as a valid target INR. High INR variability is a strong independent predictor of adverse events after valve replacement. Although some studies have supported lowering a target INR for aortic MHVs,480,481 further evaluation in larger cohorts is warranted before updating current recommendations. The use of selfmonitoring INR is associated with a lower rate of VKA-related complications in all ages.482 In a trial of lower intensity warfarin plus aspirin (INR 1.52.0) or standard warfarin plus aspirin (INR 2.03.0) after implantation of the On-X MHV in the aortic position, the similar safety of the two approaches was partly attributed to use of home INR monitoring and high degree of adherence among patients.481 Patient’s education plays an important role for achieving stable anticoagulation in the therapeutic range. Effective management of patients with unstable INR requires frequent in-clinic testing and dose titration. Because of the lack of good-quality evidence, pharmacogenetic testing cannot be recommended to guide the dosing of VKAs.

11.3.1.3 Management of vitamin K antagonist (VKA) overdose and bleeding Bleeding increases exponentially with INR >4.5.483 In case of major and/or life-threatening bleeding and in patients who need to undergo urgent surgery, the VKA should be discontinued and 10 mg vitamin K should be administrated by slow i.v. infusion and repeated every 12 h if needed. Until the anticoagulation effect is reversed, administration of prothrombin complex concentration (PCC) and/or fresh frozen plasma (FFP) therapy should be initiated according to body weight and pre-treatment INR. The efficacy should be monitored by recheck of INR at 30 min and every 46 h until normalization. The optimal time to restart anticoagulation should be discussed in relation to location of the bleeding event and interventions performed to stop bleeding and/or to treat an underlying cause.484

Table 10 Target international normalized ratio for mechanical prostheses

Prosthesis thrombogenicity Patient-related risk factorsa

None 1 risk factor

Lowb 2.5 3.0 Mediumc 3.0 3.5 Highd 3.5 4.0 AF = atrial fibrillation; LVEF = left ventricular ejection fraction. aMitral or tricuspid valve replacement; previous thromboembolism; AF; mitral stenosis of any degree; LVEF <35%. bCarbomedics, Medtronic Hall, ATS, Medtronic Open-Pivot, St Jude Medical, Sorin Bicarbon. cOther bileaflet valves with insufficient data. dLillehei-Kaster, Omniscience, Starr-Edwards (ball-cage), Bjork-Shiley and other tilting-disc valves. ESC/EACTS 2021

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