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- Tex Heart Inst J
- v.36(6); 2009
- PMC2801951
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Tex Heart Inst J. 2009; 36(6): 557–562.
PMCID: PMC2801951
PMID: 20069081
Factors Influencing Death and Long-Term Survival
Mehmet Erdem Toker, MD, Ercan Eren, MD, Mustafa Guler, MD, Kaan Kirali, MD, Mehmet Yanartas, MD, Mehmet Balkanay, MD, and Cevat Yakut, MD
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Abstract
We retrospectively investigated preoperative and postoperative characteristics in order to determine factors that affected hospital death in patients who underwent 3 or 4 separate cardiac valvular surgeries. The hospital records of 53 such patients who were operated upon from 1985 through 2006 were obtained. The patients were divided into 2 groups according to whether their initial operation was a closed mitral commissurotomy (group C, n = 33) or open-heart surgery with cardiopulmonary bypass (group O, n = 20). In group C, all patients who had initially undergone 1 or 2 closed mitral commissurotomy procedures underwent subsequent reoperations that entailed median sternotomy and cardiopulmonary bypass. Sternotomy and cardiopulmonary bypass had been used in valvular operations of all group O patients.
The total early mortality rate was 11.3% (6 of 53 patients). Multivariate analysis revealed that longer aortic cross-clamp times and double valve replacement at last operation significantly increased the risk of death. Herein, we discuss our conclusion that 3rd or 4th cardiac valvular operations incurred acceptable early postoperative mortality rates.
Key words: Cardiac surgical procedures/statistics & numerical data, heart valves/mortality/surgery, heart valve prosthesis/adverse effects/mortality/surgery, logistic models, multivariate analysis, reoperation/adverse effects/mortality/statistics & numerical data, retrospective studies, risk factors, survival rate
Two or 3 cardiac reoperations may be required after a 1st successful valvular surgery, due to complications that beset mechanical or bioprosthetic valves, such as degeneration.1,2 Before open-heart surgery became a common treatment, patients with rheumatic carditis routinely received closed mitral commissurotomy (CMC), which often mandated later reoperation due to valve degeneration or to valvular insufficiency caused by flaws in the reconstruction method. Patients who have received open mitral commissurotomy or replacement of native valves with mechanical or biological valves may require a 3rd or 4th surgical valvular procedure because of valve-related complications, including dysfunction and paravalvular leakage.
We retrospectively investigated preoperative and postoperative characteristics of 53 patients in order to identify factors that affected hospital mortality rates in patients who underwent 2 or 3 cardiac valvular reoperations.
Patients and Methods
We conducted a retrospective, comparative study of 53 patients who had undergone cardiac valvular operations for a 3rd or 4th time in our hospital from 1985 through 2006. The patients' medical records were reviewed.
Patients with complex congenital disease were excluded from the study, except for those with isolated valvular disease or ascending aortic aneurysm. Patients were divided into 2 groups in accordance with their initial operation. Thirty-three patients (Group C) had undergone CMC as their initial operation. Two of them had undergone 2nd CMC operations as their 2nd operations, and 31 had undergone open-heart procedures that involved the use of cardiopulmonary bypass (CPB). Twenty patients (Group O) had undergone open-heart procedures and had been placed on CPB for every valvular repair.
The indications for reoperation fell into 6 categories:
Paravalvular Leakage. Periprosthetic, moderate-to-severe leakage, observed upon echocardiography, that led to clinical deterioration,
Prosthetic Valve Endocarditis. Patients underwent surgery under antibiotic suppression. The diagnosis of endocarditis was supported by positive blood cultures and echocardiographic appearance.
Dysfunction of a Bioprosthesis. A bioprosthesis was found to have extensive calcification or a torn leaflet.
Dysfunction of a Mechanical Valve. Mechanical dysfunction was caused by pannus or thrombus formation.
Failed Valve Repair. Failure involved regurgitation by a valve that had been repaired previously.
Degeneration of a New Valve. It was necessary to repair or replace a valve that had not required intervention during previous open-heart operations.
Description of the Last Operation
The right common femoral artery was explored in all patients, and then cannulated in most. In the cases of uncannulated femoral arteries, the ascending aorta was cannulated after median sternotomy and exploration of the aorta. In hemodynamically unstable patients, partial CPB was achieved after cannulation of the femoral artery and vein. Median sternotomy was performed, and antegrade and retrograde isothermal blood cardioplegia was applied to cease cardiac activity. In most patients, retrograde cardioplegia cannulae were replaced directly through the right atrium after antegrade arrest of the heart and snaring of the venae cavae. The heart was vented and drilled through the right upper pulmonary vein.
Definitions
Operative death was defined as death within 30 days of the operation or before a patient's discharge from the hospital. Patients with a serum creatinine level of 2 mg/dL or more were considered to have preoperative renal insufficiency. Postoperative renal failure was defined as elevation of serum creatinine to 2 mg/dL, or to a level double that of the preoperative value. Low cardiac output syndrome was indicated by the requirement of an intra-aortic balloon pump or the infusion of inotropic agents for more than 12 hours. Postoperative cerebrovascular accident was defined as coma for longer than 24 hours or as focal neurologic deficit. Myocardial infarction was established by the presence of these 3 criteria: elevation in the myocardial fraction of creatine kinase or of troponin T, new Q waves upon electrocardiography, and new occurrence of regional hypokinesia or dyskinesia.
Statistical Analyses
The following preoperative variables were analyzed for potential correlation with postoperative death: age, sex, type of 1st surgery, time interval between 1st and last operations, cardiac rhythm, pulmonary artery pressure, preoperative renal failure, left ventricular end-diastolic dimension (LVEDD), and left ventricular end-systolic dimension (LVESD). In addition, death and long-term survival were correlated with the types of operation, including intervention to the tricuspid valve (Kay or De Vega annuloplasty, together with other valves), combined mitral valve replacement (MVR) and aortic valve replacement (AVR) in the last operation, total perfusion time, and aortic cross-clamp time (ACCT).
Data were analyzed using Statistical Package for Social Sciences software for Windows, version 10.0 (SPSS Inc.; Chicago, Ill). Descriptive statistics (mean ± SD), the Student t test, and the Mann-Whitney U test were used to compare continuous variables. To compare categorical data, the c2 and Fisher exact c2 tests were applied. The effects of ACCT and double valve replacement on death were evaluated by means of logistic regression. Survival was evaluated by the Kaplan-Meier method and the log-rank test. A P value of less than 0.05 was considered statistically significant. When appropriate, 95% confidence intervals were also presented. The data conformed to each test that was used to analyze them.
Results
Preoperative characteristics of the patients are shown in Table I. Most of the patients were women, and the mean age of the entire population was approximately 46 years. The mean age of the patients in group C was significantly higher than that in group O (P = 0.011).
TABLE I. Preoperative Characteristics of the 53 Patients
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In group C (n = 33), 5 patients underwent initial CMC in the 1960s, 7 in the 1970s, 18 in the 1980s, and 3 in the 1990s. In group O (n = 20), 8 patients underwent initial open-heart surgery in the 1980s, 10 in the 1990s, and 2 from 2000 through 2006. In group C, 2nd interventions were performed in 3 patients in the 1970s, 11 in the 1980s, 16 in the 1990s, and 3 from 2000 through 2006. In group O, 2nd interventions were performed in 2 patients in the 1980s, 12 in the 1990s, and 6 from 2000 through 2006. In group C, 3rd and 4th interventions were performed during the 1990s in 17 patients and from 2000 through 2006 in 16 patients. In group O, 3rd and 4th interventions were performed in 9 patients during the 1990s and in 11 patients from 2000 through 2006.
In group C, 2 patients each underwent 2 open procedures after 2 CMCs, and the other 31 patients each underwent 2 open procedures after 1 CMC. In group O, 1 patient underwent 4 open operations (1 right thoracotomy and 3 median sternotomies); the remaining 19 patients each underwent 3 median sternotomies. In the entire population, the reasons for cardiac surgery were rheumatic carditis (n = 51), infective endocarditis (n = 1), and congenital disease (n = 1).
Approximately one third of patients in group C sustained valvular insufficiency after reconstruction, and another third of the patients experienced bioprosthetic dysfunction. The prevalence of paravalvular leakage was 50% in group O (Table I).
As shown in Table I, LVESD and LVEDD in group O were significantly higher than in group C (both P = 0.001). Furthermore, significantly more patients in group C went longer than 10 years between their 1st and last operations (P = 0.001). As Table I shows, almost all patients had a left ventricular ejection fraction above 0.50.
Table II summarizes the percentage of patients by operative procedure and by postoperative morbidity and death. Total death was just over 11% (6/53). Although approximately 3 times more patients died in group C than in group O, this difference was not statistically significant. The causes of death were low cardiac output syndrome (n = 4), sepsis (n = 1), and cerebrovascular accident (n = 1). All 6 patients who died were women. In these 6 patients, tricuspid valve reconstruction was performed together with MVR, or with combined MVR and AVR, as the last operation.
TABLE II. Postoperative Characteristics of the 53 Patients
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At last operation, 8 of 53 patients underwent combined AVR and MVR (15.09%). Tricuspid valve reconstruction (by means of Kay or De Vega annuloplasty) was performed in 13 patients (24.5%) (Table III).
TABLE III. Comparisons in Regard to Death and Survival
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Nearly 21% of patients experienced postoperative renal failure, and cerebrovascular accident was observed in 12% of patients in group C (Table II). In all patients, the mean ACCT was approximately 84 min, and the mean total perfusion time was 123 min.
At least 10 years elapsed between the 1st and last operations in 5 of the patients who died: >30 years (1), 20 years (1), and 10 years (3).
Univariate analyses showed that tricuspid valve reconstruction performed concomitantly with other valve procedures (P = 0.027), combined AVR and MVR (P = 0.001), and longer ACCT (P = 0.005) and total perfusion time (P = 0.012) significantly increased mortality rates (Table III). Multivariate analyses revealed that elevated ACCT (P = 0.048) and double valve replacements (P = 0.041) significantly increased mortality rates (Table IV).
TABLE IV. Results of Logistic Regression Analysis
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Figure 1 shows survival as a function of years after last operation. Eight patients died during the follow-up period (4 in each group). The mean survival rate in group O was 61% ± 14.6%, and the mean survival time after the last surgery was 8.03 ± 1.12 yr. In group C, the mean survival rate was 71.3% ± 8.2%, and the mean survival time was 9.54 ± 0.98 yr. There was no statistically significant difference between the groups in mortality rate, according to the log-rank test (P = 0.98).
Fig. 1. Survival as a function of years after last operation. The numbers and the percentages of group C and group O in the figure represent the number of patients in each group and the percentages of respective survival over parallel years of follow-up.
Discussion
Our study shows that 3rd and 4th cardiac valvular operations can be performed with low in-hospital mortality rates. The mortality rate was 11.3% overall, 5% in group O (1/20), and 15.2% in group C (5/33). Although there is no statistically significant difference between the rates in each group, the higher rate in group C is of note. More patients in group C were first operated upon in an earlier decade than were patients in group O. The 2nd operations were also performed earlier in group C than in group O. Therefore, we believe that the comparatively better mortality rates in group O are due to developments over the ensuing decades in surgical techniques, myocardial preservation, anesthesia, and monitoring in the intensive care unit.
The chief reasons for the last surgeries in Group C patients were dysfunction of bioprostheses and failed valvular repair. Luciani and colleagues3 reported that dysfunction of prosthetic valves due to thrombosis is a predominant reason for reoperation. In accordance with other studies,4 the main reason for reoperation in our study was paravalvular leakage in group O. In group C patients, in whom CMC was initially performed, 12 of 33 patients underwent open mitral commissurotomy as the 2nd operation, indicating that the most common reason for the last surgery was valvular stenosis or valvular insufficiency after reconstruction.
Some studies have shown that age is a factor in death after cardiac surgery,5,6 whereas another study disputes this conclusion.7 Age was not a factor our study. More patients in group C lived more than 10 years between their 1st and last surgeries, which implies that CMC was effective in this group of patients. Successful CMC is related to the morphology of the mitral valve and the experience of the surgeon.8 We no longer perform CMC in our hospital, but in a 2006 study performed elsewhere, the reoperation rate 5 years after a CMC operation was 4% to 7%.8
Although only women died in the present study, sex differences were not a significant factor in mortality rates. However, a previous study showed evidence that female sex influenced death after cardiac surgeries.1 Upon univariate analysis in our study, ACCT and total perfusion time increased mortality rates; upon multivariate analysis, ACCT increased mortality rates. Aortic cross-clamp time and total perfusion time are related to the complexity of the surgical procedure. Biglioli and colleagues9 showed evidence that high mortality rates were related to ACCT, whereas other studies reported no correlation.10
Tricuspid valve reconstruction performed concomitantly with other valvular procedures as the last operation increased the mortality rates in our study, as did combined MVR and AVR. Other studies have also shown that these factors are indicators for disease progression. Piehler and colleagues11 determined that progression of valvular disease increases mortality rates. Lytle and associates1 found that death did not increase after the 2nd operation in comparison with death after the 1st operation; however, death increased after more than 2 valvular operations. In our study, 4 of 8 patients died after undergoing double valve replacement at last operation.
Long-term survival rates in the groups were similar. It is essential to note that although 69.8% of the patients lived 10 years or longer between the 1st and the last procedures, only 3.7% had a left ventricular ejection fraction less than 0.50. Although there is evidence that the use of preoperative computed tomography is helpful in avoiding catastrophic hemorrhage in patients who undergo more than 3 sternotomies,2 no patient in our study population experienced sternotomy-related complications. This agrees with our clinical observation that mediastinal adhesions do not cause as much trouble at 2nd reoperation as might be expected, when compared with 1st reoperation.
Summary
In our study of 53 patients, we determined that 3rd and 4th cardiac valvular operations were performed with a relatively low mortality rate. Double valve replacement and longer ACCT during the last operation increased mortality rates. Most patients with at least 10 years between their 1st and last operations had rheumatic disorders and normal left ventricular function, indicating that CMC was performed efficiently in patients with rheumatic mitral stenosis. The mortality rate was higher in group C, although not to the level of statistical significance. Second interventions were also performed in earlier decades in group C patients than in group O patients. Although 1st interventions were less invasive in group C, we believe that better mortality rates would have been observed in group O with each passing decade of surgery as improvements were made in surgical techniques, myocardial preservation, anesthesia, and monitoring in the intensive care unit.
Footnotes
Address for reprints: Mehmet Erdem Toker, MD, Yuksek Ticaretliler Sitesi Faikbey Sokak No:5 A/17, Acibadem, Kadikoy, 34718 Istanbul, Turkey
E-mail: moc.oohay@rekotrem
References
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