Benefits of mitral valve repair over replacement in the elderly: a systematic review and meta‐analysis

Mitral valve (MV) repair has demonstrated excellent short‐ and long‐term outcomes, however, its merit in the elderly population is still debated. We conducted a meta‐analysis of studies that have compared the MV repair to replacement in the elderly population.


| INTRODUCTION
Over the last decades, there has been a significant growth in life expectancy in the developed countries. Hence, the aging portion of the population has consistently increased over the years and it has been predicted that by 2030 the number of people aged 65 years and above will represent around 20% of the entire population in United States 1 while in Europe the median age will increase by 3.8 years by 2050. 2 Currently more than half of cardiac surgical procedures are performed in patients older than 75 years 3 and it has been estimated than more than 10% of the hospitalized patients aged ≥75 years have a considerable degree of mitral valve (MV) regurgitation 4 that may require intervention. Mitral valve repair (MVr) is currently preferred to mitral valve replacement (MVR) for the surgical management of degenerative MV disease 5 as it provides better shortand long-term outcomes and a lesser tendency to thromboembolic events 6 and although the durability of MVr and MVR are similar, there is a survival advantage for the former. 6 Despite these obvious advantages, the use of MVr in the elderly is still debated and some surgeons believe that reducing the cross-clamp time with a "quick" valve replacement would be beneficial for this subgroup of patients.
It has been previously shown that elderly patients are less likely to receive MV repair compared to a series of all-comers. 7 We examined the current evidence on the surgical outcome of MVr and MVR in elderly patients by conducting a contemporary systematic review and meta-analysis of previously published studies on this topic.  (last access on May 12th, 2020), screening titles and abstracts. The full-text articles were then obtained for all potentially eligible articles that clearly met the inclusion criteria and were reviewed separately if either reviewer considered the manuscript as being eligible. When the full articles were not available data were extracted from the abstract whenever possible. Any disagreement was resolved by consensus.

| Eligibility criteria
Case reports, editorials, reviews, and meta-analysis were excluded.
Nonclinical or post-mortem reports were also excluded. The inclu-   Sample means and standard deviations for numerical data were obtained directly from the studies: if they were reported as median and IQR, the mean and SD were estimated using the methods proposed by Wan et al. 8 For the analysis of time-to-event data, the estimated treatment effect and the relative standard error were calculated from the estimated HR and the log-rank variance. 9 Patient-level raw data that were calculated directly from the Kaplan   Table 2 shows the critical appraisal of the included studies (Newcastle-Ottawa Quality Assessment Scale for Cohort Studies).

| Operative surgical times
Seven studies [11][12][13][15][16][17] 21 It has to be noted that a previously published randomized study 22 showed a prolonged CPB and crossclamp time in the repair group, and the authors suggested that this was the leading cause for a prolonged ventilatory support. 22 The current meta-analysis confirms that there is no direct influence of the type of surgery on the duration of the operation and we believe this is important in elderly patients in whom shortening CPB and cross-clamp time might determine an improvement in clinical outcomes.
There are several limitations to the current analysis: a certain degree of statistical heterogeneity is present for some outcomes although it has been addressed using random effects models. As for any metaanalysis there is always the risk of publication bias and or extreme outliers: we have run bias and influential analysis to evaluate the importance of these factors (supplemental file). Another limitation is the fact that this meta-analysis includes only retrospective studies and no data are available on the complexity of the repairs that might have affected prolonged surgical timings in this group.

| CONCLUSION
In conclusion, our study demonstrates that MV surgery can be safely conducted in the elderly population with good short-and long-term outcomes. Short-and long-term survival rates are favorable for the MVr technique. MV repair should be offered to elderly patients and timely referrals for surgery should be granted even in this cohort of patients.