The operative mortality rate after redo valvular operations

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1 Clinical Outcomes of Redo Valvular Operations: A 20-Year Experience Naoto Fukunaga, MD, Yukikatsu Okada, MD, Yasunobu Konishi, MD, Takashi Murashita, MD, Mitsuru Yuzaki, MD, Yu Shomura, MD, Hiroshi Fujiwara, MD, and Tadaaki Koyama, MD Department of Cardiovascular Surgery, Kobe City Medical Center General Hospital, Chuo-ku, Kobe, Japan Background. A higher operative mortality rate has been reported after redo valvular procedures than after the primary operation. Methods. Outcomes of 330 consecutive patients undergoing 433 redo valvular operations at our institute during a 20-year period (January 1990 to December 2010) were reviewed retrospectively. The mean follow-up was 6.4 years (range, 0.05 to 1.3 years). Logistic regression analysis was used to identify factors associated with hospital death. Results. The overall hospital mortality rate was 6.7% (29 of 433 procedures). Logistic regression analysis identified only advanced New York Heart Association (NYHA) class as an independent predictor of hospital death. Overall survival at 5, 10, and 15 years was 83.6% 2.2%, 70.7% 3.4%, and 61.5% 4.5%, respectively. The 5-, 10-, and 15-year survivals for the first redo vs more than second redo groups were 86.5% 2.4% vs 74.7% 5.5%, 71.8% 3.9% vs 66.8% 6.6%, and 60.2% 5.7% vs 63.1% 7.2%, respectively (log-rank P 0.505). The 5- and 10-year survivals for NYHA class I/II vs III/IV patients were 91.5% 2.1% vs 70.4% 4.5% and 77.8% 4.1% vs 58.5% 5.6%, respectively (log-rank p < 0.005). Conclusions. Redo valvular operation in NYHA class III/IV patients is associated with high hospital death and poor long-term survival. To achieve low hospital death and good long-term survival, redo operations, including more than third redo operations, should be performed in patients with lower NYHA class. (Ann Thorac Surg 2012;94:2011 6) 2012 by The Society of Thoracic Surgeons The operative mortality rate after redo valvular operations has been previously reported as 7% to 11% higher than that after the primary operation [1 4]. However, introduction of new myocardial protective techniques, use of deep hypothermic circulatory arrest, and peripheral cardiopulmonary bypass, have contributed to reduce operative death and morbidity after redo valvular operations during the past few years [3]. Previous studies have identified various reoperative risk factors, including advanced age, sex, advanced New York Heart Association (NYHA) class, decreased ejection fraction, number of previous cardiac procedures, emergency status, and replacement of mechanical valve [1, 4 6]. We retrospectively reviewed our 20-year experience of redo valvular operations performed at Kobe City Medical Center General Hospital from 1990 to 2010 to identify the possible risk factors for hospital mortality. Patients and Methods The Institutional Review Board approved this study. We analyzed 330 consecutive patients undergoing 433 redo valvular operations at our institution during a 20-year Accepted for publication June 25, Address correspondence to Dr Fukunaga, Department of Cardiovascular Surgery, Kobe City Medical Center General Hospital, Minatojimaminamimachi, Chuo-ku, Kobe , Japan; naotowakimachi@hotmail.co.jp. period from January 1990 to December 2010, by retrospectively reviewing their medical records in accordance with Society of Thoracic Surgeons (STS) guidelines [7]. All patients included in this study had previously undergone one or more valvular surgical procedures. At redo valve replacement, the choice of the prostheses was at the discretion of the surgeon. A total of 330 (76%) of the procedures were first redo valvular operations, 83 (19%) were second redos, 16 (4%) were third redos, and 4 (1%) were fourth redos. The study included patients undergoing concomitant coronary artery bypass grafting (CABG), aortic operations, and arrhythmia operations. The outpatient follow-up clinics were performed for patients every 6 or 12 months. We also made the decision for redo operation through the outpatient clinic. The mean follow-up period was 6.4 years (range, 0.05 to 21.3 years). Table 1 reports the clinical profile of patients included in the study. Statistical Analysis The study was conducted following the Guidelines for Reporting Mortality and Morbidity After Cardiac Valve Interventions [7]. All statistical analyses were conducted with StatView 5.0 software (SAS Institute, Cary, NC). Categoric variables were analyzed using the 2 test and are expressed as percentages. Continuous variables were analyzed by Student t test or unpaired t test and are expressed as mean standard deviation. The Kaplan by The Society of Thoracic Surgeons /$36.00 Published by Elsevier Inc

2 2012 FUKUNAGA ET AL Ann Thorac Surg CLINICAL OUTCOMES OF REDO VALVULAR OPERATIONS 2012;94: Table 1. Clinical Characteristics of Patients Variables Meier method was applied to calculate estimates for long-term survival. Univariate analysis was determined by Fisher exact probability and t tests. Variables with a univariate probability value of less than 0.2, but failing to meet the statistical significance level, were submitted for multivariable logistic regression analysis to determine independent multivariable factors of death and morbidity. Results Mean SD or No. (%) (N 330) Age, years Body surface area, m Male sex 124 (38) Hypertension 81 (25) Diabetes mellitus 48 (15) Hyperlipidemia 31 (9) COPD 13 (4) Congestive heart failure 90 (27) Peripheral vascular disease 13 (4) Stroke 71 (22) Hemodialysis 5 (2) Liver cirrhosis 21 (6) Ischemic heart disease 12 (4) Atrial fibrillation 205 (62) LVEF (38) (31) (3) NYHA class I 23 (7) II 178 (54) III 97 (29) IV 32 (10) Urgency of operation Elective 291 (88) Emergency or urgent 39 (12) No. of redo operations One time 330 (76) Two times 83 (19) Three times 16 (4) Four times 4 (1) COPD chronic obstructive pulmonary disease; LVEF left ventricular ejection fraction; NYHA New York Heart Association; SD standard deviation. This study included 330 patients (124 males [38%]) who were a mean age of 61 years (range, years). The cohort underwent 433 redo valvular procedures, of which, 330 (76%) were first redo valvular operations, 83 (19%) were second redos, 16 (4%) were third redos, and 4 (1%) were fourth redos. Hospital Death The overall hospital mortality rate of redo procedures was 6.7% (29 of 433 procedures). Of the 330 patients in the cohort, 19 in-hospital deaths occurred among those who underwent their first redo operation, resulting in a mortality rate after first redo of 5.8%, whereas the mortality rate after second and higher redo procedures was 9.7% (10 of 103 procedures), which was not a statistically significant difference. In particular, patients aged older than 75 years (range, 75 to 88 years) had a hospital mortality rate of 16.7%, which tended to be higher than those who were aged younger than 75 years (p ). The causes of hospital death included multiorgan failure in 19 patients (4.4%), arrhythmia in 3 (0.7%), sudden death in 2 (0.5%), bleeding in 2 (0.5%), sepsis in 1 (0.2%), and cerebral hemorrhage in 1 (0.2%). The overall in-hospital morbidity rate was 21.9% (95 of 433 procedures). The main postoperative complications were reexploration for bleeding in 23 (5.3%), mediastinitis in 5 (1.2%), stroke in 4 (0.9%), and low output syndrome, gastrointestinal bleeding, and newly required hemodialysis in 3 patients (0.7%) each. Details of Previous and Present Valvular Interventions Previous operations included 101 aortic valve replacements and 5 aortic valve repairs with 42 biologic and 59 mechanical valves. Previous mitral valve operations included 71 repairs and 176 valve replacements with 135 biologic and 41 mechanical valves. Concomitant CABG was performed in 11 patients during their previous operation. Details of patients previous operations are summarized in Table 2. At the most recent redo operation, isolated valve operation was performed on 56 aortic and 97 mitral valves. A double-valve operation was performed in 143 patients and a triple-valve operation in 17. Concomitant CABG was required in 13 redo patients, and ascending aortic repair was performed in 13. At redo operation, in cases of the right ventricle close to the sternum or elevation of the right ventricular pressure, extracorporeal circulation was applied by peripheral cannulations before median resternotomy to prevent injury. We judged this application based on preoperative computed tomography or transthoracic echocardiography. In more than the third redo operation, we usually used extracorporeal circulation before median resternotomy. Myocardial protection consisted of antegrade or retrograde cold blood cardioplegia, or both, according to the causes of the redo operation or surgical procedures; for example, in only a mitral or aortic valve operation, without aortic regurgitation, did we use antegrade cold blood cardioplegia alone. Details about the most recent redo operations are listed in Table 3. Causes of Redo Operation The causes of the most recent redo operations are summarized in Table 4. Redo operations in 21 patients (mean age, years) were for structural valve deterioration

3 Ann Thorac Surg FUKUNAGA ET AL 2012;94: CLINICAL OUTCOMES OF REDO VALVULAR OPERATIONS 2013 (SVD) of the aortic valve, and 124 patients (mean age, years) underwent redo operation for SVD of the mitral valve. Mortality rates were 9.5% (2 of 21) for aortic redoes and 8.9% (11 of 124) for mitral redoes. Emergency or urgent redo operations were required in 4 patients who underwent an aortic valve operation and in 7 patients who underwent a mitral valve operation. These 7 patients were NYHA class III or IV. The mortality rate in emergency or urgent cases was 0% (0 of 4) after redo aortic valve operations and 28.6% (2 of 7) after emergency mitral valve operation. Four patients (mean age, 66 9 years), all of whom had an unstable hemodynamic condition preoperatively, underwent an emergency aortic redo operation for stuck valves. The valves that exhibited this problem were of the tilting disc type. Of these 4 patients, 3 died postoperatively for a hospital mortality of 75%. None of our patients had stuck mitral valves. In redo operations for non-svd, only 1 patient underwent an emergency operation in the aortic position. No hospital deaths occurred in our patients after non-svd operations in either position. Approximately 50% of the patients who presented with prosthetic valve endocarditis (PVE) in the mitral position required emergency or urgent operations for acute progression of heart failure associated with destruction of the prosthesis or hemodynamically unstable condition. Table 2. Details of Previous Operation Variables No. (%) Isolated aortic valve 62 Mitral 169 Tricuspid 6 Aortic mitral 23 Aortic tricuspid 2 Mitral tricuspid 44 Aortic mitral tricuspid 18 Others 3 Concomitant CABG 11 Ascending aortic repair 0 Aortic valve operation 106 Replacement 101 (95) Biologic 42 (42) Mechanical 59 (58) Repair 5 (5) Mitral valve operation 247 Replacement 176 (71) Biologic 135 (77) Mechanical 41 (23) Repair 71 (29) Tricuspid valve operation 18 Replacement 11 (61) Biologic 8 (73) Mechanical 3 (27) Repair 7 (39) CABG coronary artery bypass grafting. Table 3. Summary of Most Recent Redo Operation Variables No. (%) Isolated aortic valve 56 Mitral 97 Tricuspid 14 Aortic mitral 22 Aortic tricuspid 7 Aortic pulmonary 1 Mitral tricuspid 113 Aortic mitral tricuspid 17 Others 2 Concomitant CABG 13 Ascending aortic repair 13 Aortic valve operation 106 Replacement 102 (96) Biologic 57 (56) Mechanical 45 (44) Repair 4 (4) Mitral valve operation 245 Replacement 225 (92) Biologic 98 (44) Mechanical 127 (56) Repair 20 (8) Tricuspid valve operation 146 Replacement 5 (3) Biologic 5 (100) Mechanical 0 (0) Repair 141 (97) CABG coronary artery bypass grafting. Death due to PVE in the mitral position occurred in 3 patients, all with previous bioprostheses. No deaths occurred among patients who underwent replacement of a mechanical valve. Mean ages of patients with PVE in the aortic and mitral positions were and years. Nine patients with PVE in the aortic position required an emergency or urgent operation, one of whom died. NYHA class was III or IV in 4 of these 9 patients. Emergency or urgent cases in NYHA class I or II patients were associated with root abscess or coronary artery related etiology. Hospital death from PVE in aortic and mitral positions was 3 patients (11.1%) and 1 patient (5.3%), respectively. Table 4. Causes of Most Recent Emergency or Urgent Redo Operation Cause Aortic No. (%) Mitral No. (%) Prosthetic valve endocarditis 27 (9) 19 (10) Structural valve deterioration 21 (4) 124 (7) Non-structural valve deterioration 14 (1) 19 (0) Stuck valve 4 (4) 0 (0) Others 37 (1) 83 (2)

4 2014 FUKUNAGA ET AL Ann Thorac Surg CLINICAL OUTCOMES OF REDO VALVULAR OPERATIONS 2012;94: Table 5. Univariate Predictors of Hospital Death Explanatory Variables p Value First redo operation Emergency/urgent NYHA class III/IV Hemodialysis Second and more redo Age 70 years NYHA class III/IV NYHA New York Heart Association. Risk Factors for Hospital Death Univariate analysis and multivariate models were constructed to determine preoperative risk factors for hospital death after a redo valvular operation. The univariate predictors were age older than 70 years, emergency or urgent operation, advanced NYHA class, and hemodialysis. However, logistic regression analysis could not identify any independent predictors of hospital death. We next analyzed preoperative risk factors of hospital death by the number of redo operations; that is, patients with a first redo operation vs those with second and above redo operations. Univariate predictors were emergency or urgent indication, advanced NYHA class, and hemodialysis in the first redo group. Predictors in the second and above redo group were age older than 70 years and advanced NYHA class (Table 5). Type of valve, previous operation, or valve operated on were not statistically significant predictors of hospital death. Logistic regression analysis identified only advanced NYHA class as an independent multivariate predictor of hospital death in both groups (Table 6). Long-Term Survival During the mean follow-up of 6.4 years (range, 0.05 to 21.3 years), there were 49 deaths, including 28 cardiac deaths and 16 valve-related deaths. Actual survival for the remaining group without valve-related deaths was 84.0% 2.3% at 5 years, 73.3% 3.3% at 10 years, and 68.9% 4.1% at 15 years. The cause of death in 4 patients could not be discerned. Overall survival was 83.6% 2.2% at 5 years, 70.7% 3.4% at 10 years, and 61.5% 4.5% at 15 years. Kaplan- Meier estimates of survival among the first redo operation group and second and more redo groups are shown in Figure 1. Survivals for the first redo group and second Fig 1. Kaplan-Meier survival estimates are shown for the group undergoing a first redo operation and the group undergoing second and more redo operations. and more group were, respectively, 86.5% 2.4% vs 74.7% 5.5% at 5 years, 71.8% 3.9% vs % at 10 years, and 60.2% 5.7% vs 63.1% 7.2% at 15 years (log-rank p 0.505). Survival for NYHA class I/II vs class III/IV patients was, respectively, 91.5% 2.1% vs 70.4% 4.5% at 5 years and 77.8% 4.1% vs 58.5% 5.6% at 10 years (log-rank p 0.005; Fig 2). Outcomes in Patients Aged Older Than 75 Years In patients with a mean age of 78 years, NYHA class did not affect the hospital mortality rate, and no other significant risk factors were detected. Their 3-year survival was 65.3% 8.5%, which was lower than the survival rate of 85.8% 2.1% observed in patients aged younger than 75 years (log-rank p 0.005; Fig 3). Comment Redo valvular operation has always been a challenging problem, with higher mortality rates and surgical risks Table 6. Multivariate Predictors of Hospital Death Variables Odds Ratio (95% CI) p Value First redo operation NYHA class III/IV ( ) Hemodialysis ( ) Second and more redo NYHA class III/IV ( ) CI confidence interval; NYHA New York Heart Association. Fig 2. Kaplan-Meier survival estimates are shown New York Heart Association (NYHA) class I and II and class III and IV patients. The difference between these groups was statistically significant (log-rank p 0.005).

5 Ann Thorac Surg FUKUNAGA ET AL 2012;94: CLINICAL OUTCOMES OF REDO VALVULAR OPERATIONS 2015 Fig 3. Kaplan-Meier survival estimates are shown patients aged older and younger than 75 years. The difference between these groups was statistically significant (log-rank p 0.005). than the initial operation. With the increasingly aging population, cardiac surgeons are likely to encounter a greater number of elderly patients requiring a redo operation. A major cause of death after redo operation is cardiac failure with hemodynamic instability [6]. Specific surgical strategies are required during redo interventions, including extracorporeal circulation by peripheral cannulation before sternal reentry and intraoperative myocardial protection [6, 8]. Cohn and colleagues [3] reported that these strategies have reduced the operative mortality and morbidity rates of redo valvular operation. The present study demonstrated an 6.7% overall hospital mortality rate after redo procedures and that the only independent risk factor for hospital death was advanced NYHA class. Our series included heterogeneous complicated redo operations, such as multiple valve operations, concomitant CABG, and aortic repair, which are generally associated with a much higher postoperative mortality rate. The coexistence of these procedures, which would affect to some extent the hospital mortality rate, was a limitation in this study. The hospital mortality rate at our institution was satisfactory and similar to previous reports of 7% to 11% [1 4]. Given that advanced NYHA class is a risk factor for death, our results indicate that surgeons should not hesitate to perform second and above redo operations in NYHA class I or II patients in whom redo operations are indicated. We analyzed a subgroup of patients aged older than 75 years and demonstrated that their hospital mortality rate was 16.7%. Among the 7 deaths in this group, 4 patients were NYHA class III or IV. This evidence in elderly patients suggested our present recommendation, as mentioned above, is true even for elderly patients. Thus, cardiologists or cardiac surgeons should not delay a redo operation in a patient who requires the intervention merely because of advanced age: the delay could result in progressive worsening of the patient s condition. Serial follow-up and optimal early referral of patients are very important when redo valvular operations are required. Our results also suggest that use of bioprosthetic valves can be justified in younger patients, especially those at NYHA class I and II, because they can possibly withstand a redo operation with greater ease than elderly patients. Potter and colleagues [9] supported the expanded use of bioprostheses for younger patients because their data showed the risk of a redo aortic valve replacement in younger patients was similar to that for primary aortic valve replacement. Various studies have identified age, sex, year of reoperation, chronic obstructive pulmonary disease, peripheral vascular disease, advanced NYHA class, depressed ejection fraction, number of previous cardiac procedures, emergency status, infective endocarditis, and replacement of a mechanical valve as significant predictors of operative death [1, 2, 4 6, 9, 10]. Concomitant CABG was also identified as a significant predictor of hospital death [1, 11]. Our study found only advanced NYHA class was an independent predictor of hospital death. An emergency or urgent operation was not statistically significantly associated with hospital death in multivariate analysis. However, the actual hospital mortality rate after emergency operations was 20.5%, which was much higher than the 7.2% mortality rate observed after elective operation. Tang and associates [10] reported the effect of the type of the previously implanted valve on survival after redo operation. They concluded that explanting mechanical valves was associated with higher perioperative death than explanting bioprosthetic valves because of different modes of failure or presentation [10]. Jones and coworkers [11] also demonstrated that mortality was 26.1% for replacement of a mechanical valve compared with 8.6% for replacement of a bioprosthesis and that replacement of a mechanical valve was an independent predictor of operative death [1]. Lytle and associates [2], however, demonstrated no significant difference in operative death between the different types of prosthetic valves [2]. We analyzed the effect of previously implanted valve type on operative death in aortic and mitral positions, and found no significant difference in death between the types of valves in both groups. However, as Tang and coworkers [10] pointed out, causes of valve failure and presentation for redo operation were different between the two prostheses. In particular, patients who underwent replacement of a mechanical valve more frequently presented as an emergency. In our patients, the outcome of stuck aortic valves during the first 10 years was very poor, with an operative mortality rate of 75%. All of these patients presented for an emergency operation and all of their previous mechanical valves were the one-disc type, which reportedly can result in critical obstruction and rapid hemodynamic deterioration [12]. However, current disc valves, such as the bileaflet type, are less likely to result in hemodynamic instability. None of our patients have presented with a case of stuck aortic valve in recent years.

6 2016 FUKUNAGA ET AL Ann Thorac Surg CLINICAL OUTCOMES OF REDO VALVULAR OPERATIONS 2012;94: The mortality rate of PVE in the aortic and mitral positions in our study was not high. Only 3 patients with prior replacement of a bioprosthesis died, representing a mortality rate of 8.3%. Leontyev and coworkers [13] reported a mortality of 24.3% for aortic PVE. In addition, PVE patients with root abscess had a mortality rate of 40.6% vs 12.5% in those without root abscess. Other studies reported a mortality rate for PVE of 20% to 29%. Despite inclusion of patients with PVE with root abscess in our analysis, our outcome was much better than that reported previously. Although the present outcome of PVE was limited because we had a small number of patients with PVE compared with other reports, we believe that our outcome was notable. The mortality rate of SVD in both aortic and mitral positions was 9.0% in our study, which was similar to that reported by Pansini and associates [14]. They also described that patients undergoing redo operation due to SVD had a better life expectancy compared with those requiring operation for endocarditis, paravalvular leakage, and thrombosis. The overall long-term survival of patients who underwent redo valvular operation at our institute was satisfactory. In 1990, Pansini and associates [14] reported an actual 7-year survival rate of 57.3% 8%. Our study described actual survival rates of 83.6% 2.2% at 5 years and 70.7% 3.4% at 10 years. Our 15-year survival rate was 61.5% 4.5%, which we believe in is an acceptable figure. For analysis, we divided redo operation patients into the first redo operation and more than second redo groups, and analyzed their long-term survival. Survival rates for the first redo and more than second redo groups were, respectively, 86.5% 2.4% vs 74.7% 5.5% at 5 years, 71.8% 3.9% vs % at 10 years, and 60.2% 5.7% vs 63.1% 7.2% at 15 years, which were not statistically significantly different. This indicates favorable long-term survival even in patients with multiple redo procedures. We demonstrated that advanced NYHA class affected not only hospital survival but also long-term survival. Compared with NYHA class I and II patients, NYHA class III and IV patients had a significantly higher mortality rate and lower long-term survival. With greater life expectancies and the concomitantly increasing number of elderly people likely to present for operation in the future, patient age is likely to pose a growing problem. We determined that patients aged older than 75 years had a lower 3-year survival than younger patients. Although age was not found to be a risk factor for hospital mortality in our study, it did affect short-term survival. In conclusion, redo valvular operation in NYHA class III and IV patients is associated with a high hospital death and poor long-term survival. In addition, older patient age is an inevitable problem. 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