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Ann Thorac Surg 1997;63:1718-1724
© 1997 The Society of Thoracic Surgeons
Department of Thoracic and Cardiovascular Surgery, Cleveland Clinic Foundation, Cleveland, Ohio
Accepted for publication December 24, 1996.
| Abstract |
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Methods. Between January 1985 and December 1995, 146 patients underwent surgical therapy (repair or replacement) for native mitral valve endocarditis. All patients had documented bacterial endocarditis. Univariate and multivariate analyses were performed to determine predictors of hospital death, long-term event-free survival, and probability of repair. Patients were evaluated in three groups: all patients, patients with acute endocarditis, and patients with chronic endocarditis.
Results. There were ten hospital deaths (6.8%). Patients undergoing repair had a lower hospital mortality rate (p = 0.008) then those having replacement. Event-free survival was improved after mitral valve repair in the overall group (p = 0.02) and in the group with healed (chronic) endocarditis (p = 0.05). Although the acute endocarditis group demonstrated an improved event-free survival rate after mitral valve repair versus replacement (74% versus 20% at 6 years), this did not reach statistical significance.
Conclusions. We conclude that mitral valve repair is preferable to mitral valve replacement when possible, in patients with complications of endocarditis, as repair results in a lower hospital mortality and an improved long-term survival.
| Introduction |
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Prosthetic valve replacement has traditionally been the standard therapy for patients unresponsive to antibiotic therapies [2, 3], but valve replacement is associated with several long-term problems [3, 4]. The life expectancy of bioprosthetic valves is limited, especially in the mitral position [4, 5]. Lifelong anticoagulation is required if a mechanical prosthesis is used and is associated with bleeding and thromboembolic complications. Young women who wish to get pregnant cannot take oral anticoagulants because of their teratogenic effects. Moreover, valve replacement in the presence of acute endocarditis carries a high perioperative mortality rate and a substantial risk of prosthetic valve endocarditis [4, 5].
Our initial experience with mitral valve repair in patients with endocarditis has been reported [6]. We report here our experience with 146 patients undergoing mitral valve repair or replacement for endocarditis. It was undertaken to determine any advantages to repairing infected mitral valves and to determine which patients with mitral valve endocarditis could undergo repair.
| Patients and Methods |
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Early in our series, an attempt was made to have patients complete at least a 2-week course of antibiotics prior to surgical intervention. However, as our experience and confidence in mitral valve repair techniques increased, patients demonstrating clear indications for surgical intervention (hemodynamic deterioration, persistent sepsis, or mobile vegetations identified by echocardiography) were operated on with less than 1 week of antibiotic treatment. Our current preference is to intervene earlier in patients requiring operation to prevent valve leaflet destruction, which may preclude valve repair, to prevent systemic embolization from large vegetations, and to preserve ventricular function.
Presenting symptoms included shortness of breath in 71 patients, fever in 42, embolic events in 22, and syncopal episodes in 11.
One hundred two patients (70%) underwent mitral valve repair; 44 were treated with mitral valve replacement. Fifty-eight patients had evidence of acute endocarditis (39.7%), and 88 had healed (chronic) endocarditis. The presumed origin of the mitral valve endocarditis was found in only 46% of patients. Dental manipulation (35 patients) and distant superficial wounds (20 patients) were the most frequent predisposing factors. Other origins of infection included drug addiction, 5 patients; gynecologic, 3; arteriovenous fistula (dialysis), 3; and central line, 1 patient; the source was not determined in 79 (54%). The microorganisms responsible for infection were isolated from blood in 99 patients (68%) before operation (Table 1
). Streptococcus and Staphylococcus species predominated. There were no cases of fungal endocarditis.
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Indications for operation included hemodynamic deterioration (congestive heart failure and hypotension) in 103 patients (70.5%). Thirty-eight patients (26%) had evidence of mobile vegetations on echocardiography, and 5 patients had uncontrolled sepsis.
| Operative Findings |
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| Operative Technique |
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All patients operated on for acute endocarditis received 6 weeks of parenteral antibiotic therapy postoperatively. Patients undergoing mechanical valve replacement were placed on a lifelong regimen of warfarin therapy, as were patients in chronic atrial fibrillation. Patients receiving bioprosthetic valves had 6 weeks of anticoagulation therapy.
| Follow-up |
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| Statistical Analysis |
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| Results |
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Patients requiring mitral valve replacement were older (p = 0.05), had lower starting hematocrits (p = 0.0002) and higher serum creatinine levels (p = 0.005), received intravenous antibiotics longer (p = 0.0002), had longer bypass runs (p = 0.004) and longer cross-clamp times (p = 0.02), and required more packed red blood cells (p = 0.0004), more platelets (p = 0.02), and more fresh frozen plasma transfusions (p = 0.01) than patients undergoing valve repair.
There were ten hospital deaths (eight in the acute endocarditis group and two in the chronic endocarditis group), for an overall mortality rate of 6.8%. Four patients each died of prosthetic valve failure and cardiac failure, and 1 patient each died of a cerebrovascular accident and respiratory failure. Patients undergoing repair (acute and chronic endocarditis groups) had a lower overall hospital mortality rate (p = 0.008) (Table 5
). Multivariate logistic regression analysis failed to identify any predictors of hospital death.
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| Acute Endocarditis Group |
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| Chronic Endocarditis Group |
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| Complications |
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Two patients required reoperation while in the hospital postoperatively. Both eventually had valve replacement. One was a 64-year old woman who underwent mitral valve repair and coronary artery bypass grafting for ischemic mitral insufficiency. The mitral valve repair failed because of endocarditis, thus necessitating re-repair 10 weeks later. Infection occurred again, and valve replacement was performed. The patient was subsequently discharged from the hospital. The second patient underwent aortic and mitral valve replacement for bivalvular endocarditis. Nine weeks later, valve re-replacements were required for prosthetic valve endocarditis. At postmortem examination, the fibrous skeleton of the heart was infected, and there was evidence of persistent prosthetic valve endocarditis in both valves.
| Event-Free Survival |
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| Comment |
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Our study also clearly demonstrated that not all patients with complications of endocarditis are candidates for mitral valve repair and, therefore, any comparison between patients having mitral valve repair and patients having mitral valve replacement can be misleading. This is also probably true of all retrospective studies attempting to compare patients undergoing mitral valve repair with those having mitral valve replacement. Some patients undergoing mitral valve replacement had more severely damaged valves as a result of endocarditis, and inadequate leaflet tissue remained for reconstruction. Moreover, several patients requiring mitral valve replacement also underwent associated concomitant procedures (such as aortic valve replacements or coronary artery bypass grafting). This fact accounts for the prolonged cross-clamp and bypass times in these patients and most likely influenced the surgeon's decision not to attempt valve repair. Our study also revealed that patients with vegetations on the anterior or posterior leaflet and those with previous mitral valve repair procedures were more likely to require valve replacement. The appropriateness of comparing repair and replacement patients notwithstanding, patients who could undergo mitral valve repair had a lower hospital mortality rate and better midterm durability than patients who did not have repair. Therefore, when feasible, mitral valve repair should be performed for patients with acute or chronic endocarditis.
The better hospital mortality and event-free survival rates of the repair group are the result of several advantages besides being less ill that patients undergoing mitral valve repair have over those needing mitral valve replacement. Mitral valve repair has been shown to preserve left ventricular function and to avoid the inherent morbidity associated with prosthetic valves [8, 9]. It is now established that ventricular function is better preserved after mitral valve repair than after valve replacement when the chordae are excised, which is more likely to occur in patients with endocarditis (24/34 patients or 71% in our series) [8, 9].
Hospital mortality after mitral valve repair has been demonstrated to be lower than after replacement as a result of the improved ventricular function associated with preserving the subvalvular apparatus [912]. Moreover, anticoagulation is not required after mitral valve repair, and therefore, hemorrhagic complications are less common than after valve replacement [8, 9]. Patients undergoing mechanical valve replacement have a linearized rate of events (structural valvular deterioration, thromboembolism, and hemorrhage) of 5% per year [13]. Bioprosthetic valves have similar event rates [14]. Although thrombosis is unlikely to occur in bioprosthetic valves and patients are less likely to experience bleeding complications because anticoagulation is unnecessary, bioprosthetic valves develop structural deterioration at a much greater rate than mechanical valves. Furthermore, by preserving mitral valve leaflets using repair techniques, reinfection is less frequent than when a valve prosthesis is used [8, 9].
Whether intervening earlier in the course of infection before valve destruction occurred might have allowed more patients to undergo repair is unknown. During the period of our study, we adopted a more aggressive approach to patients with native mitral valve endocarditis in an effort to try to repair more mitral valves. In support of this approach, it is known that endocarditis begins on the valve leaflets where it remains for some time [15, 16]. We concur with the philosophy of Dreyfus and colleagues [17] that earlier intervention may help to ensure valve repairability. They thought earlier surgical intervention could prevent progression of the infection process while the patient completed a course of antibiotics. This also increased the likelihood of preserving the subvalvular apparatus and, thus, left ventricular function. Although only 45% of patients in our acute endocarditis group were able to undergo mitral valve repair, Dreyfus and associates [17], using a more aggressive approach to mitral valve repair, reported repair rates of 80% in patients with acute endocarditis.
Our surgical results are similar to those in previously published reports of patients with endocarditis undergoing repair or replacement. With mitral valve repair, Dreyfus and co-workers [17] also demonstrated an excellent hospital mortality rate in patients who had acute endocarditis. Likewise, the hospital mortality rate for mitral valve replacement in our study (overall, 15.9%) is similar to the 10% to 30% rate reported for mitral valve replacement in the setting of acute endocarditis by others [5, 18, 20]. Our study is noteworthy in that we report direct comparison between patients undergoing mitral valve repair and those having replacement for endocarditis, and intermediate results after valve repair for endocarditis are given.
Adequate treatment of the infection process is the major concern when operating for valvular endocarditis [19, 21]. In our study, patients able to undergo mitral valve repair demonstrated superior infection-free survival than those requiring valve replacement (95% versus 73% at 6 years). Published rates of prosthetic valve endocarditis after operation for valvular endocarditis range from 8% to 20% at long-term follow-up [9, 18, 20]. Preserving the native valve tissue during repair and avoiding prosthetic material in an infected area most certainly account for these results. Moreover, mitral valve repair in the presence of active or healed infection demonstrated similar durability and low need of reoperation compared with replacement.
We conclude that it is preferable to repair the mitral valve in patients with complications of endocarditis, as repair results in lower hospital mortality and improved long-term survival. Early intervention may also prevent leaflet destruction, thus ensuring repairability, prevent vegetation embolization, and preserve left ventricular function. Mitral valve repair is durable and resistant to reinfection in the setting of either acute or healed endocarditis. However, it is important to realize that not all patients are candidates for mitral valve repair because of the variable extent of mitral valve tissue destruction caused by endocarditis.
| Acknowledgments |
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| Footnotes |
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| References |
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