Real Structural Valve Deterioration of the Mitroflow Aortic Prosthesis: Competing Risk Analysis

Mechanical valve replacement for patients with rheumatic heart disease: the reality of INR control in Africa and beyond

The majority of patients requiring heart valve replacement in low- to middle-income countries (LMICs) need it for rheumatic heart disease (RHD). While the young age of such patients largely prescribes replacement with mechanical prostheses, reliable anticoagulation management is often unattainable under the prevailing socioeconomic circumstances. Cases of patients with clotted valves presenting for emergency surgery as a consequence of poor adherence to anticoagulation control are frequent. The operative mortality rates of reoperations for thrombosed mechanical valves are several times higher than those for tissue valves, and long-term results are also disappointing. Under-anticoagulation prevails in these regions that has clearly been linked to poor international normalised ratio (INR) monitoring. In industrialised countries, safe anticoagulation is defined as >60%-70% of the time in the therapeutic range (TTR). In LMICs, the TTR has been found to be in the range of twenty to forty percent. In this study, we analysed >20,000 INR test results of 552 consecutive patients receiving a mechanical valve for RHD. Only 27% of these test results were in the therapeutic range, with the vast majority (61%) being sub-therapeutic. Interestingly, the post-operative frequency of INR tests of one every 3-4 weeks in year 1 had dropped to less than 1 per year by year 7. LMICs need to use clinical judgement and assess the probability of insufficient INR monitoring prior to uncritically applying Western guidelines predominantly based on chronological age. The process of identification of high-risk subgroups in terms of non-adherence to anticoagulation control should take into account both the adherence history of >50% of patients with RHD who were in chronic atrial fibrillation prior to surgery as well as geographic and socioeconomic circumstances.

Long term follow up of percutaneous treatment for degenerated Mitroflow prosthesis with self-expanding transcatheter aortic valve implantation

Background

The durability of aortic valve bioprosthesis and the structural valve deterioration (SVD) are could be treated with valve-in-valve (VIV) transcatheter aortic valve implantation (TAVI). This technique has been proven to be a feasible procedure with good results in selected patients. The aim of this work was to assess the long-term results of this TAVI with an autoexpandable valve in patients with failed Mitroflow (MF) bioprosthetic aortic valves.

Methods

Single center, observational and prospective study that included 65 consecutive patients with symptomatic failed MF bioprosthetic aortic valve, treated with VIV-TAVI. The primary endpoints were clinical long-term events including all-cause mortality, cardiovascular mortality, re-hospitalization due to heart failure, stroke/transient ischemic attack (TIA) and endocarditis. Secondary endpoints were the absence of SVD or patient-prosthesis mismatch (PPM) and valve hemodynamics analysis at follow-up.

Results

Between March 2012 to July 2019, 65 symptomatic patients (age 80.4±5.9 years) with degenerated MF valves (numbers 19: 27.7%; 21: 38.5%; 23: 21.5%; 25: 12.3%) underwent CoreValve (n=11) or Evolut R (n=54) implantation (23, 26 and 29 mm sizes). The STS predicted risk of mortality was 6.39%±5.62%. The primary combined endpoint occurred in 32.3% of the cases. A total of 13 patients (20%) died during follow-up, but 4 (7.3%) from cardiovascular causes. Two patients were reported of having a stroke/TIA and 5 readmissions for cardiovascular causes were reported (2 of them within the first 30 days). Twenty-five patients (38.5%) presented PPM during follow-up, being PPM severe in 15 (23.1%).

Conclusions

Self-expanding TAVI for degenerated MF bioprosthesis has favourable long-term outcomes. It is a good option in order to avoid the risks of redo surgery in selected patients.