Our study described the experience of our center with the surgical treatment of patients with endocarditis. However, our discussion will be focused on the results obtained in patients with PVE undergoing early surgery. These patients are the most "delicate" and at risk and are often considered inoperable due to their comorbidities and clinical status. Although PVE patients are at higher risk than patients with native valve endocarditis, our study demonstrates that an early surgical approach may represent a valuable treatment option for this high-risk population. In other words, our study aims to demonstrate that early surgery in patients with PVE, albeit at very high risk, is associated with a good outcome in most cases.
In a matched retrospective cohort study of 139 dialysis patients, Farrington et al. reported that the risk of PVE and death after valve replacement was significantly higher in dialysis patients than in patients without dialysis (5). However, the mortality rate was less than 20% and the timing of intervention was unknown. This finding is consistent with our results, suggesting that operation should be taken into consideration also in patients at higher risk, even if burdened by a high mortality rate. Likewise, we also recorded a correlation between preoperative renal insufficiency and mortality. In this population, any delay to intervention or medical treatment alone can result in higher mortality (6). Although we did not include a control group on medical therapy, the mortality rate we recorded in operated patients was lower than in previous studies with a control group (6). Additionally, it is well-known that PVE is associated with high mortality particularly when urgent surgery is needed (7). In the analysis by Revilla et al (7), the main indication for urgent surgery was heart failure. This could also be ascribed to the waiting time until surgery leading to worsening of heart failure and hemodynamic instability in emer-gency. In our opinion, a “wait-and-see” approach may have resulted in critical clinical conditions and extensive anatomical injury (8, 9).
Also the surgical technique plays a role, especially if a complex procedure for en-docarditis with annular or root destruction should be performed, though associated with higher mortality (10). In case of aortic root involvement, several prosthetic models seem helpful in facilitating the radicality of the procedure or favoring resistance to recurrence (11, 12). In our population of high-risk patients, we chose to adopt the simplest technique by minimizing ischemic time, and priority was given to the removal of the infected tissue and implantation of the new prosthesis in an area distant from the previous one (13). In other words, radicality is key but a fast procedure is very important because prolonged cross-clamp time is correlated with postoperative mortality.
Age is another factor to be taken into consideration when evaluating operability. In patients undergoing surgery for infective endocarditis, regardless of whether native valve endocarditis or PVE, available evidence shows that advanced age is associated with higher mortality rates up to 20% in patients above 75 years (14). Of the 4 patients aged > 75 years included in our PVE population, only one died, supporting surgical indication also in this high-risk patient subset undergoing re-operation. Advanced age is a risk factor common to all interventions in cardiac surgery and not only for endocarditis per se.
We believe there may be a “bias” towards some patients who are considered to be at too high risk for surgery. For instance, patients undergoing transcatheter aortic valve implantation (TAVI) have been found to have a risk for developing infective endocarditis similar to those undergoing surgical aortic valve replacement, and no differences have been reported between these two patient subsets when undergoing surgery/re-surgery (15–17). These findings should prompt us to evaluate operability and the risk of mortality at the time of first intervention. Patients undergoing TAVI and re-operated for endocarditis, given the historical period and the chronological sequence, are at least at intermediate risk if not considered inoperable (2). It is also likely that, in some specific conditions related to endocarditis, the risk scores we commonly use are not helpful in correctly assessing the patient's predicted risk (18). Also in our study, some patients had a EuroSCORE II > 60/70%, which would have represented an absolute contraindication for intervention. In contrast, the surgical procedure in these patients was performed with good efficacy, indirectly suggesting the incomplete appropriateness of these scores in some cases of endocarditis.
In our opinion, a surgical and early approach should be adopted in these high-risk patients, as this strategy performs better than a “wait-and-see” or non-surgical approach, regardless of the predicted risk score. This opinion is shared by other colleagues who also addressed the issue of hospital costs, concluding that these patients should receive a rapid diagnosis and treatment in order to improve morbidity, mortality and reduce postoperative hospital costs (19). The delay to surgery is not merely due to a “wait-and-see” approach but can also be related to diagnostic delays. In this regard, we fully agree with our colleagues who, by developing institutional protocols, have managed to reduce diagnostic times and, consequently, improve survival (20). The take home message of our study therefore is that all PVE patients should be operated early, though larger studies are necessary to confirm our findings.