Discussion:
The optimal surgical treatment for MVR remains under debate. The latest reports demonstrate MV repair is considered to be superior to replacement (7, 16). The excellent outcomes of surgical repair with a recommendation of risk stratification and earlier intervention when the probability of durable repair is high show low operative mortality and morbidity rates (2, 4, 7). In view of these findings, the rate of MV repair in Germany increased from 37.6% to 62.8% between 2000 and 2015 (17). These findings however remain debatable considering reports showing a benefit for preventing recurrence of MVR and rehospitalization with MV replacement. We decided to analyze our institutional results comparing repair and replacement using a propensity-matched analysis to homogenize the treatment groups and to perform a detailed statistical comparative analysis.
The age of a patient has long been considered an independent predictor of MV replacement (18). Silaschi et al. (19) showed patients who underwent MV repair were older compared to the replacement group. Thourani et al. (20) found that survival in the repair group was significantly higher than that in the replacement group in patients younger than 60 years, whereas this difference was not visible in patients older than 60. In our study, propensity-score matching was performed prior to analyze, with age being one of the baseline variables.
Vassileva et al (18) demonstrated that patients who had diabetes mellitus, myocardial infarction, stroke, previous cardiac surgery, and/or previous PCI in their history had a tendency to undergo replacement. In our study, the forementioned characteristics as well as the EuroSCORE II were similar between the two groups. In light of this, we believe that the decision against repair should not be based on the patient’s age or history.
It is known that many factors are affecting the short and long-term outcomes of MV surgery. In our study, by performing a univariate logistic and multivariate regression analysis, we found that patients with CAD, or a history of it, had increased risk of in-hospital mortality. That could be due to reduced heart function as a result of the disease, and the acute side effects of CPB and cardioplegia which may cause an impairment in heart function in the first few hours after surgery, thus increasing the probability of developing low-cardiac output syndrome and the respective impact. Similar to Carino et al (13), our study showed that a high EuroSCORE II was associated with an increased 30-day mortality and higher adverse long-term outcomes. EuroSCORE II is widely considered an important predictor for 30-day mortality after cardiac surgery. It was validated in some studies in patients undergoing MV surgery (13, 21, 22) but we only found one study that explored the ability of EuroSCORE II to predict the 30-day mortality in patients undergoing MV surgery. They found that EuroSCORE II overestimates 30-day mortality (13).
Some surgeons believe MV repair is more complex, requiring longer X-clamp time and having a higher risk of recurrence (19). In our analysis, we observed that the difference between the two groups in CPB and X-clamp time were not statistically significant. These results were in agreement with the findings of Silaschi et al. (19) and Chivasso et al. (23), In contrast, Farid et al. (24) showed that patients who underwent repair have had shorter CPB and X-clamp times compared with those who underwent replacement. We know that cardiac and operative trauma can be reduced when CPB and X-clamp time are shorter, depending on the surgeon’s experience.
In this study, we observed two cases of ring dehiscence requiring re-surgery. This complication after atrioventricular valves repair, particularly after MV repair, is not rare and is reported in 13–42% of procedural failures in MV annuloplasty repair (25). This complication led us to implement a modified approach by placing four pledgeted sutures on the A1, A3, P1 and P3 segments to reinforce the stability of the ring. Since using this strategy, we have not observed any new cases of ring dehiscence in our patients also those who not included in this trial.
The AATS Guidelines, AHA/ACC and ESC recommend repair to treat severe degenerative and ischemic MVR (2, 4, 26). The evidence for this recommendation is derived from single-center studies; however, the superiority of MV repair led the guidelines to consider the low probability of achieving a durable repair. This served as a reason to pass patients to specialized MV repair centers (2, 4). Some retrospective studies have reported some advantage of repair, in particular the operative mortality was lower compared to that of replacement (27-30). However, there is a multitude of studies showing no evidence for a preference of one intervention over the other (10, 16, 20, 28, 31).
This clinical investigation demonstrates that patients undergoing repair have similar mortality within 30 days after surgery, but lower mortality after 5 years compared with patients undergoing replacement.