The major clinical guidelines for valvular diseases vary regarding the recommended age for the use of mitral bioprostheses. The 2020 American guidelines recommend their use in patients older than 65 years, while the 2021 European guidelines suggest their use in patients older than 70 years; both recommendations are classified as Class IIa. Bioprostheses are generally recommended for patients with reduced life expectancy or comorbidities requiring additional surgical interventions, as well as those at higher risk of hemorrhagic complications. These recommendations are based on the low thromboembolic and hemorrhagic risk profiles of bioprostheses, which eliminate the need for long-term anticoagulation. However, their limited durability poses significant challenges for younger patients, who are more likely to require reintervention due to structural valve deterioration (SVD). This deterioration is not only attributed to dystrophic calcification but may also involve an immunological component, particularly in younger patients. Both guidelines share a Class I recommendation to engage in shared decision-making with patients, considering their preferences, lifestyles, and comorbidities.
In routine clinical practice, the primary criterion for prosthesis selection is the anticipated risk of reintervention due to structural deterioration, given that this entails significantly higher risk compared to the initial surgery. Currently, alternative procedures to open surgical reintervention, such as transcatheter mitral valve-in-valve (MViV) techniques, are available. Although these options are promising, robust data on their long-term efficacy and durability remain limited.
This multicenter retrospective study includes data from two U.S. hospitals, Northwestern Medicine and Michigan Medicine, encompassing patients who underwent mitral valve replacement with bioprostheses between 2004 and 2020. Patients with prior mitral valve replacements who presented to either institution were not excluded. The study aimed to evaluate the durability of mitral bioprostheses by analyzing age-stratified cumulative incidences of mitral prosthesis replacement.
A total of 1,544 patients were evaluated, with a mean age of 66 years, and the majority were women (58.8%). The cohort was divided and compared across age groups. Thirty-day mortality was 5.4%, and the incidence of postoperative stroke was 4.9%. The cumulative incidence of reintervention for structural valve deterioration (SVD) in the total cohort was 6.2% at 10 years and 9.0% at 12 years. The 10-year cumulative incidence of reintervention for SVD was significantly higher in patients aged 40–69 years (8.7%) compared to those aged 70 years or older (p<.0001). These differences in cumulative incidence of mitral reintervention by age were consistent only among patients without a history of endocarditis or dialysis. Mortality following mitral reintervention was 4.4% (4 of 90 patients), with two cases occurring after open surgery and two after transcatheter therapy.
Of these mitral reinterventions, 77.8% (70 of 90 patients) were due to SVD. Among this subgroup of patients, the cumulative incidence at 10 years was 26.2% for patients aged 30–39 years, 7.4% for those aged 40–49 years, 14.3% for those aged 50–59 years, 5.9% for those aged 60–69 years, 2.1% for those aged 70–79 years, and no reinterventions were observed in patients aged 80 years or older. The authors noted that the incidence curve for SVD reintervention remained nearly flat among patients aged 40–69 years, with a 12-year reintervention risk of 12.4% for SVD. They concluded that their findings challenge trends observed in previous studies, suggesting that the durability of mitral bioprostheses may be better than expected in patients aged 40–69 years. Furthermore, they argued that, given the low reported mortality rates following reintervention and current alternatives such as transcatheter procedures, clinical guidelines should reconsider the age recommendations for the use of bioprostheses in the mitral position.
COMMENTARY:
This study reopens an important debate regarding the durability of mitral bioprostheses in younger patients and the selection of prosthesis type. The authors suggest that current clinical guidelines should be revised to incorporate this new evidence. In recent years, there has been an increasing trend toward the use of bioprostheses in patients younger than 65 years. However, this practice is being implemented with limited evidence regarding the long-term durability of mitral bioprostheses. The primary study supporting the current age-based recommendations in clinical guidelines, conducted by Goldstone et al., reported significantly higher 15-year mortality rates for mitral bioprostheses in patients aged 40–49 years (44.1% vs. 27.1%) and 50–69 years (50.0% vs. 45.3%). In contrast, no significant differences were observed between bioprostheses and mechanical prostheses in patients aged 70 years or older. Another key study on the SVD of mitral bioprostheses, conducted by Bourguignon et al., showed that freedom from reoperation due to mitral SVD declined significantly over time: 82% at 10 years, 50% at 15 years, and 25% at 20 years, with an expected prosthetic durability of approximately 14 years in patients younger than 65 years.
The strengths of the reviewed study include its large sample size of 1,544 patients and the low 30-day mortality rate following mitral reinterventions (4.4%). Additionally, the study incorporates the analysis of newer-generation mitral bioprostheses and evaluates alternative transcatheter techniques (e.g., valve-in-valve mitral), allowing for the inclusion of patients previously considered inoperable in earlier series. This provides a more contemporary perspective on the available therapeutic options.
Despite the positive findings, the study has significant limitations in supporting its conclusions. First, the follow-up period is insufficient to adequately assess mitral bioprosthetic SVD, as only 14% of patients reached 10 years of follow-up and 7.3% reached 12 years. This suggests that the low observed reintervention rate may be due to most of the cohort not yet developing SVD due to the short follow-up period. Extending the follow-up duration would allow for a more rigorous evaluation of mitral reintervention rates. Another limitation is the high mortality rate observed during follow-up (36.2% of the cohort), which acts as a competing event, potentially reducing the number of observed mitral reinterventions. Furthermore, the study was funded by Edwards Lifesciences®, which raises the possibility of economic interests influencing the results, given that transcatheter reintervention techniques are only feasible for patients with previously implanted bioprostheses.
A revision of clinical guidelines based on updated data would be beneficial for the cardiovascular community. However, additional independent, randomized studies with longer follow-up periods are necessary to support potential changes to current recommendations.
REFERENCE:
Romano M, McCarthy PM, Baldridge AS, et al. Should mitral valve replacement age guidelines be lowered due to better bioprosthetic mitral valve durability? J Thorac Cardiovasc Surg. 2024;168(5):1448-1458.e4. doi:10.1016/j.jtcvs.2023.10.012
