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Ann Thorac Surg 2006;82:1385-1390
© 2006 The Society of Thoracic Surgeons

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Original Articles: Cardiovascular

Reoperation of the Aortic Valve in Octogenarians

^a Department of Cardiothoracic Surgery, Heart and Diabetes Center NRW, North-Rhine Westfalia, Ruhr University Bochum, Bad Oeynhausen, Germany
^b Department of Cardiology, Heart and Diabetes Center NRW, North-Rhine Westfalia, Ruhr University Bochum, Bad Oeynhausen, Germany

Accepted for publication April 27, 2006.

^_* Address correspondence to Dr. med. Eitz, Klinik für Thorax- und Kardiovaskularchirurgie, Herz- und Diabeteszentrum NRW, Georgstr. 11, 32545 Bad Oeynhausen, Germany (Email: teitz{at}hdz-nrw.de).

	Abstract

Top Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
BACKGROUND: Because of increasing life expectancy of patients with heart valve replacement and a limited durability of heart valve bioprostheses, cardiac reoperation becomes necessary in a significant percentage of patients. Reliable data on mortality and risk factors in octogenarians after replacement of aortic valve prostheses are scanty, however.

METHODS: We retrospectively analyzed 71 patients aged 80 years and older who underwent cardiac reoperation of the aortic valve (69 bioprostheses, 2 mechanical prostheses) between 1991 and 2004 at our heart center. Survival rate of the study cohort was compared with a control group of octogenarians matched for age, sex, and year of aortic valve replacement. To assess predictors of 30-day survival and 3-year survival, we performed univariate and multivariate analyses.

RESULTS: Survival rates at 30 days, 1 year, 3 years and 5 years were 83.6%, 76.1%, 70.8%, and 51.3%, respectively. Results did not differ significantly between the study cohort and the controls. Patients with reoperation had an estimated median survival of 5.6 years. Postoperative complications such as low cardiac output syndrome and intestinal failure were the only independent predictors of 30-day survival (p = 0.020 and p = 0.015, respectively). Low cardiac output, intestinal failure, and diabetes mellitus were independent predictors of 3-year survival (p = 0.001 to 0.033).

CONCLUSIONS: Our data demonstrate that it is possible to achieve an acceptable outcome in octogenarians who have reoperation of the aortic valve prosthesis. Early and mid-term survival is predominantly influenced by unexpected postoperative complications and not by preoperative risk factors, with the exception of diabetes mellitus.

	Introduction

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In European populations, between 11% and 18% of the people are older than 65 years [1]. In line with the rise in life expectancy in western societies, the number of elderly patients presenting for open heart surgery is increasing. In Germany, approximately 40% of all patients who underwent cardiac surgery with the heart–lung machine in 2003 were 70 years and older. Of a total of 94,700 procedures, almost 17,000 were valve related, and most were valve replacements [2]. Although there is general agreement that patients younger than 60 years should receive mechanical heart valve prostheses and patients older than 70 years should be provided with a bioprosthesis, there is no consensus about the choice of prosthetic heart valve for patients in their seventh decade of life [3]. In contrast to mechanical prostheses, bioprostheses usually do not require postoperative anticoagulation. The durability of biologic valves is limited, however, and structural valve deterioration can begin 5 to 10 years after valve implantation [4–6].

Nowadays, life expectancy of patients with heart valve replacement is almost that of an age-matched healthy population [3]. Therefore, approximately 10% of patients with an aortic valve replacement who were between 60 and 70 years old at the time of their first operation needed replacement of their prosthetic valve in the ninth decade of their life [7].

Valve replacement in octogenarians is a high-risk procedure [8, 9]. Some publications also indicate that a cardiac redo procedure further increases morbidity and mortality in this age group [10, 11]. However, these earlier studies did not focus on valve replacement, or the number of replacement of valve prostheses was rather small, or both [10–12]. Consequently, little reliable data are available on mortality and its risk factors in octogenarians after replacement of aortic valve prostheses. In the present study, we report the outcome and risk factors for survival in 71 octogenarians who had prosthetic aortic valve replacements.

	Material and Methods

Top Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
Patients
We performed a retrospective analysis of all patients aged 80 years and older who underwent replacement or refixation of an aortic heart valve prosthesis between May 1991 and October 2004 at the Heart Center North-Rhine-Westfalia, Bad Oeynhausen, Germany. The Ruhr University Ethics Committee, Bochum, Germany approved the study, and the need for individual informed consent was waived. Only patients who had a disabling physical or mental status or malignancies with poor prognosis were excluded from reoperation. Of 71 patients who met the criteria for cardiac reoperation of the aortic valve, 4 patients already had two previous cardiac operations. Two mechanical heart valves and 68 bioprostheses had to be explanted. In 1 patient, a bioprosthesis needed refixation. All procedures had to be performed because of valve-related adverse events.

The median time interval since the first cardiac operation was 8.0 years (interquartile range, 4.6 to 9.8 years). Four patients had had their first aortic valve operation in their seventh decade of life. All other patients were aged older than 70 years when the first valve replacement was performed. With only 30 procedures performed until December 1999, the majority (41 operations) were done since January 2000. Approximately 60% (41) of the 68 explanted bioprostheses were Mitroflow heart valves (Sorin Group Inc, Mitroflow Division, Vancouver, BC, Canada), whereas it was implanted in 86.7% of our patients who received their first aortic valve bioprosthesis during the study period. The Mitroflow valve was followed by the Hancock II (Medtronic Inc, Minneapolis, MN) in 7, Biocor (St. Jude Medical GmbH, Nürnberg, Germany) in 4, Aspire (tissuemed, Leeds, UK) in 3, and others in 13. No significant difference was found in the time intervals related to valve type between the two procedures.

Surgical Technique
A median sternotomy was performed in all patients, followed by aortic and right atrial cannulation. Cardiopulmonary bypass was carried out with moderate hypothermia. Generally, pulsatile perfusion was used, only in patients with severe cerebrovascular disease cardiopulmonary bypass was performed with nonpulsatile flow. Cold crystalloid cardioplegia was administered to achieve myocardial protection.

Study Procedures
We used the medical records of the patients to assess age, sex, anthropometric data, preoperative New York Heart Association (NYHA) functional class, left ventricular ejection fraction, concomitant diagnoses, and indications for valve prosthesis replacement, concomitant procedures, and postoperative complications. Coronary artery disease was considered to be present if at least one coronary artery had a stenosis of 50% or more of the vessel diameter. If possible (depending on the coronary artery morphology), concomitant revascularization of these vessels was performed. Completely obstructed coronary arteries with obvious infarction of the related myocardium were not revascularized.

We contacted all patients by telephone in September 2005 to assess long-term survival. If a patient died during follow-up, we requested the medical report from the general practitioner or from the emergency hospital to document the causes of death.

Statistics
Statistical evaluations were performed with SPSS 11 (SPSS Inc, Chicago, IL). Categoric variables were reported using the numbers and percentages. For comparative evaluations, the Fisher exact test or the ² test (categoric variables) were used. Continuous variables were expressed as mean values ± standard deviation. Survival rates were calculated with the Kaplan-Meier product-limit estimator.

Survival rate of the study group was compared with a group of patients who had received a Mitroflow bioprothesis in the aortic position at our heart center. The patients of the control group had their first cardiac surgery and were matched with the study group for age, sex, and year of operation. The control group belonged to a larger group of patients that was described in more detail elsewhere [4]. The log-rank test was used to test for differences in survival rates between groups. Survival rate was also compared with a cohort matched for age and gender from the German population [13].

For the study cohort, associations of factors with 30-day mortality and mid-term (3-year) survival were first tested in a univariate Cox regression model. Every univariate variable that showed marginal significance (p < 0.15) was then tested in a Cox multivariate model and removed stepwise if no significant influence was proved. The variables tested were age, sex, body mass index, ejection fraction, hypertension, diabetes mellitus, atrial fibrillation, stroke, renal insufficiency, peripheral and cerebral vascular disease, coronary artery disease, chronic obstructive pulmonary disease, NYHA functional class, emergent operation, revascularization, postoperative renal complications, gastrointestinal failure, low cardiac output syndrome, rethoracotomy, neurologic complications, inotropic support, resuscitation, additional cardiac surgery, and additional aortic surgery. Values of p < 0.05 were considered statistically significant.

	Results

Top Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
In Table 1, the baseline characteristics of the study group are given in comparison with the control group. Data were comparable between the groups. In most of the patiens with reoperation, the cause of aortic valve reoperation was structural valve degeneration (76.1%), followed by paravalvular leakage, endocarditis, and a combination of these causes. The prostheses were from different manufacturers: 43 Mitroflow Synergy prostheses, 11 Hancock prostheses, 2 St. Jude Medical Standard prostheses, 8 St. Jude Medical Biocor prostheses, 1 ATS Medical valve (Minneapolis, MN), 3 Aspire Aortic prostheses and 1 Carpentier Edwards valve (Edwards Lifesciences Corp, Irvine, CA).

In the univariate analysis, diabetes mellitus and several intraoperative and postoperative factors were predictors of 30-day mortality. In the multivariate analysis, however, only low cardiac output syndrome and intestinal failure remained independent predictors (p = 0.020 and p = 0.015, respectively). Of various preoperative and operative variables, stroke was the only risk factor related to low cardiac output (p = 0.015), and ejection fraction was the only factor associated with intestinal failure (p = 0.031).

Survival curves did not differ significantly between the study group and the control group (Fig 1). Survival at 30 days, 1 year, 3 years, and 5 years was 83.6%, 76.1%, 70.8%, and 57.0% in the patients with reoperation and 93.0%, 87.3%, 70.4%, and 51.3%, respectively, in the patients who had their first aortic valve operation. Patients with cardiac reoperation had an estimated median survival of 5.6 years. The survival rate in the study group and also in the control group was lower than in an age-matched and gender-matched cohort of the German population.

View larger version (19K): [in this window] [in a new window]   Fig 1. Kaplan Meier survival estimates for octogenarians with a reoperation of their aortic valve prosthesis (bottom line) compared with octogenarians who had their first aortic valve replacement (middle line) and an age-matched and gender-matched cohort from the German population (top line). Results did not differ between patients with reoperation and the control group (p = 0.646).

Postoperative anticoagulation was advised in patients with low ejection fraction (<30%), postoperative atrial fibrillation, or history of atrial fibrillation, and if a mechanical valve prothesis was chosen. Anticoagulation therapy became necessary in 36 of the 71 patients with cardiac reoperation. We prescribed coumarin derivatives in a dose that allowed the patients to achieve an international normalized ratio (INR) target range of 2.0 to 3.0.

Of the 33 reoperated on patients on who were still attainable during follow-up, 25 lived at home, 5 lived at home with mobile care support, 2 lived in an old age home, and 1 lived in a nursing home.

	Comment

Top Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
This investigation demonstrates that only postoperative complications such as low cardiac output syndrome and intestinal failure were independent risk factors of 30-day survival in our cohort of reoperated on octogenarians. Moreover, mid-term survival was similar in octogenarians with reoperation of the aortic valve compared with a group of patients, matched for age, gender, and date of operation, who had their first aortic valve replacement. Likewise, all control patients and most of the octogenarians in the study group received a Mitroflow bioprosthesis. In addition, the two groups were comparable in a variety of clinical parameters; therefore, it is rather unlikely that mortality rates of the 2 groups were influenced by study bias.

In our patients, aortic valve reoperation carried a relatively high risk of 30-day mortality. Others [3, 12] have described similar results in their reports of 13% and 28% 30-day mortality rates, respectively. However, the high percentage of preoperative risk factors in our patients demonstrates that the selection criteria for cardiac surgery were less restrictive than in other studies [11, 14].

Because life expectancy of octogenarians is generally limited and cardiac surgery is associated with substantial early mortality [15–17], it has been suggested that it might be important to identify risk factors that may adversely affect mortality [12]. We were unable to determine preoperative risk factors for 30-day mortality, however. We cannot definitively rule out that the statistical power was insufficient to reveal further independent predictors of 30-day mortality, but progress in cardiac surgery has probably lead to a relatively high survival rate even in multimorbid patients. Our data of postoperative complications such as intestinal failure and low cardiac output as independent risk factors of early surgical mortality confirm results of previous publications [18]. These complications are still difficult to handle.

We do not use Swan Ganz catheters prophylactically, but in consideration of the results of this study, they are now used more liberally to manage postoperative hemodynamic treatment. Mechanical circulatory support such as intraaortic balloon pump and extracorporeal membrane oxygenation is also applied more extensively than in the past.

The higher 30-day mortality for patients undergoing reoperations than for octogenarians undergoing their first cardiac operation is hard to explain. Rather than a reduction to age and reoperation itself, a multifactorial origin has been suggested [12]. In this context, the increased technical complexity of reoperative procedures must not be overlooked. Supporting this assumption is that more postoperative complications occurred in the reoperated on patients than in the control group.

Mid-term mortality was significantly influenced by factors that are related to early surgical mortality, such as low cardiac output syndrome, use of inotropic drugs, and intestinal failure. This is obviously because early mortality and its causes still contributed significantly to the total number of deaths at the 3-year follow-up. Diabetes mellitus, another independent predictor of 3-year mortality, is also a well-known risk factor for survival in the general population.

Our data do not support the assumption that cardiac reoperation is per se associated with higher mortality rates in octogenarians compared with patients having their first cardiac operation. In Germany, mean life expectancy of an 82-year-old woman is 7.5 years and for an 82-year-old man, 6.3 years [19]. Because median postoperative life expectancy was 5.6 years in our cohort, those patients who survived their in-hospital stay had a very similar life expectancy compared with the general population.

A mere prolongation of life without emphasis on the patient's postoperative quality of life cannot be the aim of surgery in such a patient cohort, however. In octogenarians, postoperative stroke certainly is a major contributor to a decreased quality of life [20]. The low incidence of irreversible neurologic complications, together with a significant improvement in postoperative NYHA functional class, indicates an improved quality of life in our patient group. Moreover, it is noteworthy that a significant number of reoperated on patients were still living at home at follow-up.

Although almost all our patients were aged older than 70 years when they received their first aortic valve replacement, the median time interval until reoperation was only 8 years. The Mitroflow bioprosthes is recommended for patients aged older than 70 or 75 years [4, 21]. Structural valve deterioration, as the most important reason for reoperation of the aortic valve, can begin 5 to 10 years after implantation in this bioprosthesis [4] as well as in those from other manufacturers [5, 6].

An extended indication for the implantation of mechanical valve prostheses may be an alternative to aortic valve reoperation. Current generation mechanical valves provide minimal gradients, especially in small aortic roots, and have acceptable flow pattern and left ventricular mass regression [13]. Moreover, the hazard of thromboembolism and anticoagulant-related bleeding is very low, especially if the opportunity of INR self-management is used [22]. Consequently, the hazard of reoperation in patients aged older than 80 years may be much higher than the risk of thromboembolism. It is also noteworthy that half of the patients of our study cohort had an indication for oral anticoagulation.

Whether it is desirable or not, in times of reduced economic resources in European health systems, ethical as well as pecuniary aspects also play an increasing role in the question of surgery for octogenarians. Because we cannot offer them an alternative effective medical therapy, octogenarians who need their aortic valve prosthesis replaced are left in a miserable condition with a poor prognosis if surgery is denied. Considerable follow-up costs because of repeated hospital admissions and the need of care will be inevitable although the patients' life expectancy is short. Therefore considering that, almost the same criteria are used for younger patients with the emphasis, that surgery should not be delayed until they are highly symptomatic, reoperation of the aortic valve in this age group is justified.

In summary, our data demonstrate that it is possible to achieve an acceptable outcome in octogenarians who have reoperation of the aortic valve prothesis. Early as well as mid-term survival is predominantly influenced by unexpected complications and not by preoperative risk factors, with the exception of diabetes mellitus.

	Acknowledgments

Top Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
We thank Dr Edward Murray for his assistance in writing the manuscript.

	References

Top Abstract Introduction Material and Methods Results Comment Acknowledgments References

 

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This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Dirk Fritzsche Georg Kleikamp Dieter Horstkotte Reiner Körfer Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Eitz, T. Articles by Körfer, R. Search for Related Content PubMed PubMed Citation Articles by Eitz, T. Articles by Körfer, R. Related Collections Cardiac - other Related Article