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Ann Thorac Surg 2007;84:459-465
© 2007 The Society of Thoracic Surgeons

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Original Articles: Cardiovascular

Quality of Life After Implantation of Bileaflet Prostheses in Elderly Patients: An Anticoagulation Work Group Experience

^a Department of Cardiothoracic Sciences, Second University of Naples, Naples, Italy
^b Department of Cardiovascular Surgery and Transplants, V. Monaldi Hospital, Naples, Italy

Accepted for publication April 16, 2007.

^_* Address correspondence to Dr Vicchio, Via Cassano 150, Naples, 80144, Italy (Email: marianovicchio{at}libero.it).

	Abstract

Top Abstract Introduction Material and Methods Results Comment References

 
Background: The aim of the study was to examine our experience with the implant of bileaflet mechanical prostheses and with a centralized management of anticoagulation and the related risks in patients aged older than 70 years, focusing on the resulting expectancy and quality of life.

Methods: Between January 1988 and January 2005, 681 consecutive patients older than 70 years (mean age, 73 ± 3.3 years) underwent bileaflet prostheses implantation in an isolated procedure (77%) or concomitant with other procedures (23%). Data were retrospectively collected, and follow-up was conducted by mean of outpatient chart review and outpatient clinic controls. Follow-up included assessment of perceived quality of life through the Medical Outcomes Trust Short Form 36-Item Health Survey tool (SF-36). The scores obtained by the patients were compared with those of the Italian general population matched for age and sex.

Results: Hospital mortality was 11.8%, and 74 late deaths (12.3%) occurred. Mean follow-up was 4.38 ± 2.85 years. Actuarial survival was 85.2% ± 0.014% at 1 year, 77.9% ± 0.017% at 5 years, 74.2% ± 0.02% at 10 years, and 71.8% ± 0.031% at 15 years. The mean international normalized ratio variability was 4.5% ± 1.2%. Freedom from bleeding was 98.7% ± 0.005% at 5 years and 98.3% ± 0.007% at 10 and 15 years. Freedom from thromboembolism was 99.1% ± 0.004% at 5 years, and 98.3% ± 0.007% at 10 and 15 years. The mean SF-36 scores in the study patients were significantly higher than those of the general population matched for age and sex (p < 0.001 in all domains).

Conclusions: Septuagenarian patients receiving mechanical valve prostheses did not experience increased rates of anticoagulation-related complications and perceived a satisfactory quality of life.

	Introduction

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The increased life expectancy of the Western population in the last decade [1], associated with the improvements in surgical standards and postoperative care, has progressively expanded the age criteria of operability in cardiac surgery [2]. As a consequence, the number of elderly patients undergoing heart valve replacement has been increasing, as well as their long-term survival.

In particular, patients are presenting for aortic valve replacement at a progressively older age, and in the general population, up to 4% of subjects aged older than 75 years are found to have severe aortic stenosis [3]. Mitral valve replacement is also indicated in elderly patients, in whom the most frequent etiologies are ischemic heart disease, endocarditis, and floppy mitral valve [4]. The decision for surgical indication in this patient subset is complex, and along with chronologic age, it should also take into account biologic age, comorbidities, quality of life, and severity of symptoms. In addition to long-term survival, valve-related complications and postoperative quality of life are main concerns for elderly patients requiring surgical treatment of heart valve disease.

The present retrospective study was undertaken to examine our 17-year experience with the implant of bileaflet mechanical prostheses in patients older than 70 years, evaluating the long-term outcomes, with particular focus on the safety of oral anticoagulation in this setting and on the impact that heart valve surgery with mechanical substitutes and consequent anticoagulation may have on expectancy and quality of life.

	Material and Methods

Top Abstract Introduction Material and Methods Results Comment References

 
Patient Population
Between January 1988 and January 2005, 681 patients older than 70 years underwent mechanical prosthesis implantation consecutively. By policy, mechanical devices were preferred at our institution unless associated diseases were present that contraindicated lifelong anticoagulation. All patients were included who received a bileaflet mechanical prosthesis on an elective, urgent, or emergency basis, either isolated or concomitantly with another cardiac procedure. Excluded from analysis were 168 septuagenarians who received biologic valve substitutes during the same time period and 104 concurrent elderly patients undergoing mitral valve repair. Our institution’s Ethics Committee approved this study and waived the need to obtain patient consent.

In-Hospital Management
All patients underwent preoperative full cardiologic screening, including transthoracic or transesophageal echocardiography and coronary angiography. All operations were performed by the same group of surgeons. Cardiopulmonary bypass methods were uniform throughout the study. Systemic moderate hypothermia was used in all cases, along with myocardial protection through crystalloid hyperkaliemic cardioplegia infusion into the aortic root in case of normal aortic valve competence or directly into the coronary ostia in case of aortic valve regurgitation, associated with continuous topical cooling with cold saline.

All patients received postoperative anticoagulant therapy with oral sodium warfarin. The international normalized ratio (INR) was routinely checked daily during the postoperative hospital stay, then weekly through the first postoperative month, and then on indication from our dedicated anticoagulation outpatient clinic (by default, once every 3 or 4 weeks). For patients with bileaflet mechanical prostheses in the aortic position, the target INR was between 2.0 and 3.0 before 2000 and 1.8 and 2.5 thereafter, whereas for bileaflet prostheses in the mitral position, we recommended INR values of between 2.5 and 3.5 throughout the study.

Follow-Up
Our institution includes an outpatient clinic structure that monitors anticoagulation therapy. Ambulatory INR (or earlier on prothrombin activity) checks are performed 5 days a week, and an average of 176 ± 48 blood samples per day are collected, mainly from young and older patients with valve prostheses but also from patients with atrial fibrillation, pacemakers, and other indications. Five nurses are dedicated to blood drawing and a medical team to performing the physical examinations, completing each patient’s anticoagulation chart (reporting the INR value, the time between INR checks, and every possible complication occurred), and updating anticoagulant therapy. Adverse events, with particular focus on bleeding, transient ischemic attacks, and reversible or nonreversible ischemic neurologic deficits, are classified according to the "Guidelines for Reporting Morbidity and Mortality After Cardiac Valvular Operations" as proposed by The Society of Thoracic Surgeons [5]. When appropriate, an echocardiogram follows the physical examination.

In June 2006, we began to assess, during the controls of the anticoagulation therapy, patients’ perceived quality of life through the administration of the Medical Outcomes Trust Short Form 36-Item Health Survey (SF-36, Italian version) tool [6, 7].

For the purpose of the present analysis, data on the operation and the early postoperative period were retrospectively collected by hospital chart and outpatient chart review, whereas follow-up data of hospital survivors were derived mainly from activities at our ambulatory clinic and by telephone interview. The anticoagulation results, the data on every complication that possibly occurred, and the scores obtained for the SF-36 test for each patient were retrospectively entered in an electronic database. INR variability (percentage of values outside the therapeutic range) was calculated for each patient.

All patients had been seen at our outpatient clinic or followed-up by telephone interview, or both, at least once since their discharge. In particular, 451 (75%) of the 601 hospital survivors attended periodic controls at our ambulatory clinic (median of the maximum number of visits per year, 14; range, 11 to 25), and by June 2006, had already undergone a recent visit (within the last 2 months). Of the other 150 patients (70 of whom attended satellite regional anticoagulation centers that followed the same anticoagulation protocol as ours), 84.6% were contacted by telephone and then visited in our outpatient clinic to update their follow-up. Thus, 578 hospital survivors were visited between April and June 2006, for a 96.2% completeness of clinical follow-up.

Statistical Analysis
Continuous data were expressed as mean ± standard deviation and compared using the Student t test. Discrete variables were compared using the ² test. Factors significantly associated with adverse outcomes were introduced in a multivariate logistic regression model to identify independent predictors of hospital and long-term mortality. Kaplan-Meier actuarial analyses of survival rates and of freedom from valve-related complications were performed. Scores obtained in each of the eight domains of the SF-36 were compared with those reported [8] for the Italian population matched for age and sex. A difference yielding a value of p < 0.05 was considered statistically significant. SPSS 13.0 statistical software (SPSS Inc, Chicago, IL) was used for analysis.

	Results

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Preoperative and Intraoperative Data
Preoperative characteristics of the study population are reported in Table 1. The mean age was 73.9 ± 3.3 years (range, 70 to 86 years). There were 382 (56.1%) women and 299 (43.9%) men. A total of 488 patients (70.5%) received a bileaflet mechanical prosthesis in the aortic position, 149 (21.9%) in the mitral position, and 52 (7.6%) received both mitral and aortic valve replacement. Forty-six patients (6.8%) had a history of cardiac operation. At time of the surgical procedure, 64 patients (9.4%) were in New York Heart Association (NYHA) functional class IV, 445 (65.4%) were in class III, and the remaining 172 (25.2%) were in class II. All patients underwent a preoperative echocardiographic evaluation. Echocardiographic data are presented in Table 2.

Mean follow-up was 4.55 ± 3.21 years (median, 4.25 years; 3099.97 patient-years; range, 18 months to 16 years). During the follow-up time, 74 late deaths (12.3%) were recorded, consisting of sudden death in 11 patients, myocardial infarction in 3, bleeding in 3 (2 intracranial, 1 gastric), ischemic stroke in 1, bowel infarction in 1, neoplasm in 16, respiratory failure in 11, cirrhosis in 6, dementia in 4, intestinal occlusion in 2, sepsis in 1, postoperative death after reoperation for prosthetic endocarditis in 1, and old age and generalized decay in 14 patients.

Actuarial survival (including hospital mortality) was 85.2% ± 0.014% at 1 year, 77.9% ± 0.017% at 5 years, 74.2% ± 0.02% at 10 years, and 71.8% ± 0.031% at 15 (Fig 1). When the study population was divided in subgroups by site of prosthetic valve implantation, the mitral site subgroup had lower survival at 10 years than the aortic site subgroup (69.1% ± 0.044% versus 76.5% ± 0.023%); however, this difference was not statistically significant (p = 0.17; Fig 2).

View larger version (16K): [in this window] [in a new window]   Fig 1. Actuarial survival in the study population (line) is shown by the Kaplan-Meyer method.

View larger version (22K): [in this window] [in a new window]   Fig 2. Actuarial survival in patient subgroups of prosthetic implantation site is shown by Kaplan-Meyer method. Aortic valve replacement (AVR) is shown by the black line, mitral valve replacement (MVR) is shown by the medium gray line, and AVR plus MVR is shown by the light gray line.

View larger version (13K): [in this window] [in a new window]   Fig 3. Actuarial freedom from hemorrhagic complications in the follow-up (line) is shown by the Kaplan-Meyer method.

View larger version (14K): [in this window] [in a new window]   Fig 4. Actuarial freedom from thromboembolic complications in the follow-up (line) is shown by the Kaplan-Meyer method.

View larger version (14K): [in this window] [in a new window]   Fig 5. Actuarial freedom from valve-related complications in the follow-up (line) is shown by the Kaplan-Meyer method.

View larger version (84K): [in this window] [in a new window]   Fig 6. Scores obtained in eight domains of the Medical Outcomes Trust Short Form 36-Item Health Survey tool by the study population (clear bars) compared with scores from the Italian population (patterned bars) matched for age and sex.

	Comment

Top Abstract Introduction Material and Methods Results Comment References

It should be stressed that nowadays, elderly patients referring for cardiac procedures are often physically active, and the symptoms of valve disease significantly limit daily activity and quality of life [15]. They probably represent a "selected" subset of patients with a longer expectancy of life than believed, and their risk of reoperation after bioprosthetic valve replacement has been underweighted in the past.

In 2001, Sidhu and colleagues [16] reported on an experience with 547 septuagenarians undergoing aortic or mitral valve replacement with biologic versus mechanical prostheses. They showed comparable 12-year survival rates but a higher incidence of hemorrhagic complications in the mechanical group [16]. That study, however, did not acknowledge the intensity of anticoagulation in the patients experiencing bleeding complications.

Horstkotte and colleagues [17] evidenced a remarkable reduction in hemorrhagic events, without an increase in thromboembolisms, in patients maintaining an INR between 2.2 and 3.4. With modern lower-intensity anticoagulation protocols, similar results have been reported for both mechanical and biologic valves in terms of all anticoagulation-related complications.

The variability of INR over time seems to be more a relevant factor than the target INR itself, as emerged in the study by Butchart and colleagues [18]. Our mean INR variability value fell within the "low variability" rank according to Butchart and colleagues [18]. Notably in their study, the subpopulation with low INR oscillations was characterized by the lowest observed long-term mortality rates. Close control of the adequacy of anticoagulation can achieve a reduction in INR sways and likely lower rates of hemorrhagic events in elderly patients as well as in younger patients [19]. In our previous study comparing patient groups significantly different for age (>70 years versus <45 years) and homogeneous for type of procedures (all isolated aortic valve replacements), no differences emerged for long-term freedom from hemorrhagic events and from valve-related mortality [20], underlying the importance of a dedicated institutional anticoagulation control activity.

The 10-year survival and freedom from valve-related and anticoagulation-related events observed in our experience appears excellent for a patient population older than 70 years of age. It favorably compares with other series both of mechanical and biologic valve replacement [10, 21, 22]. We believe that the accurate centralized follow-up in a dedicated outpatient anticoagulation center may account for these results.

Self-assessment and self-adjustment strategies have been tested in the management of anticoagulation for heart valve prosthesis patients, with similarly good results. They are intended to improve patient’s quality of life, although in the light of our SF-36 results, the avoidance of temporarily or permanently invalidating thromboembolic and hemorrhagic events, resulting from the combination of a lower-intensity protocol and a closer anticoagulation follow-up, could be more important a determinant of quality of life than the frequency of INR checks.

Health-related quality of life is a multidimensional concept based on the patient’s perception of his or her health and integrates not only physical functioning but also psychologic status and social dimensions. Standardized questionnaires, especially those self-completed by patients, are a practical, efficacious, and inexpensive method of collecting data. Because improvement in quality of life is considered to be one of the principal goals of valve surgery [15], methods of quality-of-life assessment are increasingly being adopted in the clinical research in this field. From reports on postoperative quality of life, patients deciding among treatment options may value information about the change in quality of life that they can expect after a valve procedure. Therefore, quality of life needs to be assessed in large and well-defined patient subsets, and it is particularly important to evaluate quality of life in elderly patients, who have a higher prevalence of comorbidity, a more severe surgical stress, and a higher risk of postoperative complications, all factors that may hinder improvement in quality of life.

Although numerous methods exist for evaluating quality of life of patients [23], the validated SF-36 questionnaire [7, 24] is comprehensive yet concise, can be completed in 10 to 15 minutes, and can be easily administered [6]. It enables the assessment of any limitation of the patient’s physical, psychologic, and social functioning. In the present study, we obtained significantly higher scores in all domains of the test than the mean general Italian population matched for age and sex. When interpreting this result, it should be considered that more than 70% of the patients in our study population were in NYHA functional class III to IV before the operation, so a high percentage of our patients had experienced a moderate-to-severe limitation in their daily activity. Symptom relief and the return to previous lifestyle can probably increase the perception of a patient’s own health status.

Similarly, the general population scores are probably underestimated because healthy elderly individuals tend to unconsciously compare their current physical and psychologic performances with those of their youth. Similar differences between elderly patients who have had heart valve replacement and the age-matched control population, in particular for what concerns the social functioning and emotional domains, were claimed by other authors in series of valve replacement [25].

A limitation of this study is that it is missing a comparison with a group of elderly patients undergoing biologic prostheses implantation in terms of clinical outcomes and quality of life. This was also due to the lack of a strict routine follow-up of tissue valve patients at our outpatient clinic and to their significantly older mean age (data not shown), which hampered the possibility of a correct comparison. However, we believed that the good survival rate and low incidences of hemorrhagic and thromboembolic complications that we observed in the elderly patients with mechanical valves represented by themselves interesting findings to describe. Others have already shown that elderly patients with biologic valves also obtain higher quality-of-life scores compared with the general age-matched population [25].

During the follow-up, we recorded 11 sudden deaths. According to the current guidelines for reporting events, they could be imputed to fatal hemorrhagic or embolic events. Unfortunately, because of cultural characteristics of our region, we could not investigate the causes of those deaths by autopsy for the lack of the family’s consent. However, all 11 patients presented normal INR values in the last records of their anticoagulation chart and had stable levels of anticoagulation in their last months of life. In 3 patients, the blood drawing had been performed within the last 6 days before death. Seven of these patients had also undergone an echocardiographic control in the last 6 months of life that had excluded prosthetic malfunction.

The aim of all medical and surgical therapies is the cure of the disease status or the improvement of life expectancy and quality of life, or both. Our results demonstrated safety and effectiveness of our therapeutic strategy of bileaflet mechanical prostheses implantation in elderly patients because it allowed us to achieve both of the targets. We believe that what reduces the quality of life is not the frequency of the anticoagulation therapy controls but the occurrence of anticoagulant-related complications. Our centralized monitoring, with the application of a uniform protocol of anticoagulation, associated with a closer control of the INR, allowed us to reduce the incidence of events related to anticoagulant therapy, positively influencing the perceived QOL.

	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): Mariano Vicchio Alessandro Della Corte Marisa De Feo Giuseppe Santarpino Luca S. De Santo Gianpaolo Romano Giuseppe Caianiello Michelangelo Scardone Maurizio Cotrufo Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Vicchio, M. Articles by Cotrufo, M. Search for Related Content PubMed PubMed Citation Articles by Vicchio, M. Articles by Cotrufo, M. Related Collections Valve disease Related Article