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Ann Thorac Surg 2001;71:S253-S256
© 2001 The Society of Thoracic Surgeons

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Valvular bioprostheses over 15 years

Aortic valve replacement with mechanical and biologic prostheses in middle-aged patients

^a Department of Surgery, Montreal Heart Institute, and the University of Montreal, Montreal, Quebec, Canada
^b Department of Medicine, Montreal Heart Institute, and the University of Montreal, Montreal, Quebec, Canada

Address reprint requests to Dr Carrier, Montreal Heart Institute, Research Center, 5000 Belanger St East, Montreal, PQ, H1T 1C8, Canada
e-mail: carrier{at}icm.umontreal.ca

Presented at the VIII International Symposium on Cardiac Bioprostheses, Cancun, Mexico, Nov 3–5, 2000.

	Abstract

Top Abstract Introduction Material and methods Results Comment References

 
Background. Mechanical prostheses are used in young patients and bioprostheses in the elderly because of the higher rate of structural failure of bioprostheses. The objective of the present study was to compare results after aortic valve replacement with mechanical (CarboMedics) and biologic (Carpentier-Edwards pericardial) in middle-aged patients.

Methods. Five hundred twenty-one patients, aged between 55 and 65 years, who underwent aortic valve replacement with mechanical (n = 363) or biologic (n = 158) prostheses were reviewed.

Results. The 10-year actuarial survival rate averaged 66% ± 6% in patients implanted with mechanical valves compared with 75% ± 4% in patients implanted with biologic valves (p = 0.2). The 10-year freedom rate from thromboembolism, hemorrhage, and endocarditis averaged 92% ± 7%, 97% ± 2%, and 99% ± 1%, respectively, in patients with mechanical valves compared with 91% ± 3% (p = 0.03), 99% ± 1% (p = 0.4), and 95% ± 2% (p = 0.01), respectively, in those with biologic valves. The 10-year freedom rate from all valve-related complications averaged 90% ± 7% and 83% ± 4%, respectively (p = 0.01).

Conclusions. The freedom rate from all valve-related complications was higher among patients with mechanical valves compared with biologic valves 10 years after aortic valve replacement in middle-aged patients.

	Introduction

Top Abstract Introduction Material and methods Results Comment References

 
Biologic and mechanical heart valve prostheses have been widely used in patients with aortic valve disease. Although aortic homograft remains an option, most patients with aortic valve disease undergo valve replacement with mechanical prostheses in the young and with biologic prostheses in the elderly [1]. It is unlikely that another randomized trial comparing newer mechanical with biologic prostheses will ever be performed, especially in very young and in elderly patients in which significant data support the current choice of prostheses [2, 3]. Yet, the choice of prostheses in middle-aged patients remains controversial because of the higher rate of structural dysfunction in younger patients with bioprostheses and because of the risk of hemorrhage or thromboembolism related to the anticoagulation treatment of a mechanical prosthesis.

Our experience with mechanical and biologic prostheses is characterized by the use of mainly two prostheses, the CarboMedics mechanical valve (CarboMedics, Austin, TX) [4] and the Carpentier-Edward pericardial (C-E pericardial, Baxter Healthcare Corporation, Santa Ana, CA) bioprosthesis [5], with the two prostheses being implanted in all age groups throughout the last 20 years. Thus, our experience offers a unique opportunity to compare the long-term results of mechanical versus biologic prostheses.

The objective of the present study was to compare the 10-year results after aortic valve replacement (AVR) with mechanical (CarboMedics) and biologic (C-E pericardial) prostheses in the middle-aged patient.

	Material and methods

Top Abstract Introduction Material and methods Results Comment References

 
The medical records of 526 patients, aged between 55 and 65 years, who underwent AVR with either a mechanical (CarboMedics, n = 363) or a biologic (C-E pericardial, n = 158) prosthesis between 1982 and 1999 were reviewed. All patients were prospectively followed at the Montreal Heart Institute Valve Clinic with a follow-up visit on a yearly basis. The follow-up was complete in all except 3 patients (99%).

Valve-related complications are reported according to the Guidelines of the Ad Hoc Liaison Committee of The Society of Thoracic Surgeons and The American Association of Thoracic Surgery [6].

The data are presented as mean and standard deviation. Differences between groups were analyzed using the Student’s t test or Fisher’s exact test. Analysis of survival and of event-free survival (thromboembolism, endocarditis, hemorrhage, valve replacement, all valve-related complication) was performed using the Kaplan-Meier method and the log-rank test. Proportional hazards regression was used to study the influence of covariates (age, sex, associated coronary artery bypass grafting, reoperation, and the type of prosthesis implanted) and the 10-year mortality after AVR. The same analysis was also performed to study the influence of covariates on the 10-year freedom rates from all valve-related complications. The statistical significance was established at a p less than 0.05.

	Results

Top Abstract Introduction Material and methods Results Comment References

 
Characteristics of patients
There were 254 men (70%) and 109 women (30%) with a mean age of 61 ± 3 years in the group receiving mechanical valves compared with 120 men (76%) and 38 women (24%) with a mean age of 61 ± 3 years in the group receiving biologic valves (p = 0.2). Fifty-eight patients (16%) underwent redo AVR with CarboMedics valves compared with 22 patients (14%) with C-E pericardial valves (p = 0.6). One hundred one patients (28%) underwent associated coronary artery bypass grafting in the CarboMedics group compared with 41 patients (26%) among those with C-E pericardial valves (p = 0.7). Most patients of both groups (223 [61%] and 95 [60%], respectively) underwent implantation of 23-mm and 25-mm prostheses (Table 1).

Immediate and long-term survival
The overall 30-day mortality averaged 4.7% (17 of 363) in patients with mechanical and 2.5% (4 of 158) in those with biologic prostheses (p = 0.3). The 10-year actuarial survival rate averaged 66% ± 6% in patients who underwent implantation of mechanical prostheses compared with 75% ± 4% in those with bioprostheses (p = 0.2; Fig 1).

View larger version (19K): [in this window] [in a new window]   Fig 1. Actuarial survival rates with early deaths included. (Carbomedic = patients who underwent implantation of mechanical prostheses; C-E = patients who underwent implantation of Carpentier-Edwards bioprostheses.)

View larger version (18K): [in this window] [in a new window]   Fig 2. Actuarial survival rates of patients who underwent isolated aortic valve replacement. (Carbomedic = patients who underwent implantation of mechanical prostheses; C-E = patients who underwent implantation of Carpentier-Edwards bioprostheses.)

Long-term results
The 10-year freedom rate from thromboembolism, hemorrhage, and endocarditis averaged 92% ± 7%, 97% ± 2%, and 99% ± 1%, respectively, in patients with mechanical valves compared with 91% ± 3% (p = 0.03), 99% ± 1% (p = 0.4), and 95% ± 2% (p = 0.01), respectively, in those with biologic valves.

The 10-year freedom rate from valve dysfunction and from valve replacement averaged 99% ± 1% and 99% ± 1%, respectively, in patients with mechanical valves compared with 92% ± 3% (p = 0.04) and 93% ± 3% (p = 0.1), respectively, in those with biologic valves.

The 10-year freedom rate from all valve-related complications averaged 90% ± 7% in patients with mechanical valves compared with 83% ± 4% in those with biologic valves (p = 0.01; Fig 3). The 10-year freedom rate from all valve-related complications except endocarditis averaged 90% ± 7% in patients with mechanical valves compared with 86% ± 4% in those with biologic valves (p = 0.01). The rate of survival free from all valve-related complications averaged 52% ± 9% in patients with mechanical valves compared with 66% ± 5% in those with biologic valves (p = 0.6).

View larger version (20K): [in this window] [in a new window]   Fig 3. Actuarial freedom rates from all valve-related complications. (Carbomedic = patients who underwent implantation of mechanical prostheses; C-E = patients who underwent implantation of Carpentier-Edwards bioprostheses.)

	Comment

Top Abstract Introduction Material and methods Results Comment References

 
The choice of a heart valve prosthesis for AVR in middle-aged patients remains controversial. The present study shows that mechanical and biologic prostheses offer similar 10-year survival rates in middle-aged patients. Although patients with biologic prostheses have higher rates of valve dysfunction and replacement, the rate of hemorrhage was higher among mechanical patients. Moreover, whereas the choice of a prosthesis had no effect on the 10-year survival after AVR, the use of a mechanical valve significantly decrease the global risk of all valve-related complications throughout the 10-year follow-up of the study. Yet, survival-free from all valve-related complications was identical between the two groups.

The present study has several limitations. The choice of the prosthesis was left to individual surgeons and their patients, and the practice has changed during the period of the study. Biologic prostheses were favored for middle-aged patients during the initial part of the study whereas the mechanical prostheses were mostly used in recent years. The follow-up time is significantly longer in patients with biologic valves compared with patients who underwent implantation of a mechanical prosthesis. However, the analysis of the 10-year results after AVR with the two prostheses is a unique opportunity to compare both prostheses short of a randomized clinical trial.

Several studies have shown that the C-E pericardial prosthesis and the CarboMedics mechanical valve both offer excellent clinical results after AVR [7–10]. Cosgrove and colleagues [11] suggested that the freedom rate from structural valve deterioration of the C-E pericardial prosthesis was low at 10 years, averaging 95%, particularly in patients 65 years and older. In addition, Jamieson and colleagues [12] showed that thromboembolic and hemorrhagic complications after AVR with bileaflet mechanical prostheses occur more frequently and result in more deaths in patients 65 years of age and older than in younger patients. Milano and colleagues [13] also showed that anticoagulant-related hemorrhage limits the use of mechanical valves in the elderly. Thus, there is good evidence supporting the use of bioprostheses in patients older than 65 years of age because of a low rate of structural deterioration and a low incidence of thromboembolic and hemorrhagic complications [14].

In the present study, the freedom rate of thromboembolic complications averaged 99% in CarboMedics and 95% in C-E prostheses 5 years after AVR, comparing favorably with the experience of Jamieson and colleagues [12]. Although the freedom rate of structural dysfunction averaged 92% 10 years after AVR with the C-E bioprosthesis, the overall freedom rate of all valve-related complications, 90% with mechanical and 83% with biologic valves at 10 years, significantly favored the use of a mechanical prosthesis in this group of middle-aged patients.

In conclusion, mechanical and biologic AVR offers similar 10-year survival in middle-aged patients. Patients with biologic prostheses have higher rates of valve dysfunction and replacement resulting in higher overall freedom rates from all valve-related complications. Yet, survival free from all valve-related complications was similar in the two groups. Thus, AVR with the mechanical prosthesis CarboMedics remains our treatment of choice in middle-aged patients, unless there is a specific contraindication to the use of anticoagulation therapy.

	References

Top Abstract Introduction Material and methods Results Comment References

 

1. Bonow R.O., Carabello B., de Leon A.C., Jr, et al. ACC/AHA guidelines for the management of patients with valvular heart disease: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol 1998;32:1486-1588.[Free Full Text]
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3. Canadian Cardiovascular Society Consensus Conference. Surgical management of valvular heart disease. Ottawa, Canada: Canadian Society of Cardiology, October 1999.
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6. Edmunds L.H., Jr, Clark R.E., Cohn L.H., Grunkemeier G.L., Miller D.C., Weisel R.D. Guidelines for reporting morbidity and mortality after cardiac valvular operations. Ann Thorac Surg 1996;62:932-935.[Abstract/Free Full Text]
7. Fiane A.E., Geiran O.R., Svennevig J.L. Up to eight years’ follow-up of 997 patients receiving the CarboMedics prosthetic heart valve. Ann Thorac Surg 1998;66:443-448.[Abstract/Free Full Text]
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10. Pelletier L.C., Carrier M., Leclerc Y., Dyrda I. The Carpentier-Edwards pericardial bioprosthesis: clinical experience in 600 patients. Ann Thorac Surg 1995;60:S297-S302.
11. Cosgrove D.M., Lytle B.W., Taylor P.C., et al. The Carpentier-Edwards pericardial aortic valve. Ten-year results. J Thorac Cardiovasc Surg 1995;110:651-662.[Abstract/Free Full Text]
12. Jamieson W.R., Miyagishima R.T., Grunkemeier Gl, et al. Bileaflet mechanical prostheses for AVR in patients younger than 65 years and 65 years and older: major thromboembolic and hemorrhagic complications. Can J Surg 1999;42:27-36.[Medline]
13. Milano A., Guglielmi C., De Carlo M., et al. Valve-related complications in elderly patients with biological, and mechanical aortic valves. Ann Thorac Surg 1998;66:S82-S87.
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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 Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Carrier, M. Articles by Pelletier, L. C. Search for Related Content PubMed PubMed Citation Articles by Carrier, M. Articles by Pelletier, L. C. Related Collections Valve disease