Ann Thorac Surg 2003;75:1815-1819
© 2003 The Society of Thoracic Surgeons
Original article: cardiovascular
Replacement of the aortic valve in patients under 50 years of age: long-term follow-up of the St. Jude medical prosthesis
Robert W. Emery, MDa*,
Carla A. Erickson, RNa,
Kit V. Arom, MD, PhDa,
William F. Northrup, III, MDa,
Thomas E. Kersten, MDa,
Thomas J. Von Rueden, MDa,
Demetre M. Nicoloff, MD, PhDa
a Cardiac Surgical Associates, PA, Minneapolis/St. Paul, Minnesota, USA
* Address reprint requests to Dr Emery, John Nasseff Heart Hospital, 2356 University NEW, STE 258, St. Paul, MN 55407, USA.
e-mail: dremery{at}csa-heart.com
Presented at the Poster Session of the Thirty-eighth Annual Meeting of The Society of Thoracic Surgeons, Fort Lauderdale, FL, Jan 28–30, 2002.
 |
Abstract
|
|---|
BACKGROUND: Aortic valve replacement in the young adult (aged 18 to 50 years) is a choice between a mechanical prosthesis with attendant lifelong anticoagulation or biological prostheses of varying types that may have limited life expectancy in this age group.
METHODS: The Cardiac Surgical Research Foundation database was accessed to determine long-term outcomes in patients having aortic valve replacement with the St. Jude Medical Valve. This database has been privately maintained since the world’s first St. Jude Medical (SJM) valve implant in 1977. Patients were contacted by questionnaire or by telephone if the survey was not returned. Follow-up was 93% complete.
RESULTS: From October 1977 through October 1997, 271 patients less than 50 years of age had isolated aortic valve replacement. Follow-up was 1957 patient years. Thirty-day operative mortality was 1.1% with 18 late deaths, 4 of which were valve related. Ninety percent of survivor INR responses indicated a frequency of monthly INR checks or less. Valve-related events including percent per patient year and mortality related to these events included thromboembolism, 6 episodes (0.3% per patient year, no deaths); anticoagulant-related bleeding, 6 events (0.3% per patient year, 2 deaths); paravalvular leak, 6 events (0.3% per patient year, 2 deaths); valve thrombosis, 2 events (0.1% per patient year, no deaths); and endocarditis, 3 events (0.15% per patient year, no deaths). There was no incidence of structural valve failure.
CONCLUSIONS: The SJM valve has a long record of excellent performance with durability lasting more than 20 years. The incidence of untoward events is low and death over time due to valve-related complications is low (4 of 271). The SJM valve has become our valve of choice for younger patients.
|
Introduction
|
|---|
Doctor Emery discloses that he has a financial relationship with St. Jude Medical, Inc.
Replacement of the aortic valve is the standard therapy for disease of the native valve. While repair of the valve can be completed, that is rarely indicated and the long-term results are unknown [1]. Unless specific indications such as the wish to bear children exist, bioprosthetic heart valves are used less commonly in younger patients because of the limited life expectancy of the prosthesis in relation to the patient [2].
Introduced in 1977, the bileaflet mechanical valve has become the most commonly implanted prosthetic heart valve and the St. Jude Medical (SJM) Bileaflet Valve is the most successful with more than 1 million implanted [3]. Because the use of a mechanical prosthesis requires chronic anticoagulation other innovative therapies for valve replacement such as the Ross procedure or valve or aortic root replacement with human homografts have been proposed, especially in younger patients. Each has significant limitations. Yet risk factors for thromboembolism are reduced in younger patients as age in and of itself is a risk factor for thromboembolism. Additional risk factors including coronary artery disease, supraventricular arrhythmias, regional ventricular wall motion abnormalities, and poor ventricular function are also less common in younger patients. Recent data indicate that thromboembolism may be related more to patient rather than to valve factors [4]. We predicted that valve-related events would be less common in younger patients and that a lower dose anticoagulant regimen could be utilized. This study was undertaken to determine the long-term results of valve replacement with a mechanical prosthesis in younger patients.
|
Material and methods
|
|---|
In October 1977 one of the authors (DMN.) implanted the world’s first St. Jude Medical (Little Canada, MN) aortic valve prosthesis. Cardiac Surgical Research Foundation has maintained a database for all patients having valve replacement with the SJM valve from that date. Fol-low-up was conducted after October 1997. The database has been updated every 5 years. The database is modified from that of The Society of Thoracic Surgeons by adding windows specifically for our group.
Inclusive in the study dates 2,390 patients underwent aortic valve replacement with the SJM valve and 271 patients (11%) were less than 50 years of age. Our experience in the pediatric population has been previously published and this report focuses on the patient cohort aged from 18 to 50 years [5]. Patients were contacted by mailed questionnaire and those not responding or in whom questions arose as to valve-related events were contacted by phone or through their local physician. Follow-up is 93% complete and includes 1,957 patient years. There were 201 (75%) male and 70 female patients. The average age was 40 years. Preoperatively 23% were New York Heart Association (NYHA) class III or IV. The preoperative comorbid risk factors and etiology of valvular disease are shown in Table 1.
Valve-related events are reported using the guidelines of Edmunds and associates [6].
Statistical methods
Nonparametric Kaplan -Meier methodology was utilized to calculate all event curves. Continuous variables are expressed as mean ± standard deviation. Linearized rates are expressed in percent per patient years or percent freedom from event.
All procedures were conducted on cardiopulmonary bypass with a membrane oxygenator. Surgeon-specific antegrade or retrograde cardioplegia was utilized in all cases. A transverse aortotomy was made above the sinotubular ridge and after thorough decalcification the appropriately sized valve was implanted using interrupted horizontal mattress braided suture. The prosthesis was most commonly implanted with the leaflet parallel to the interventricular septum. Both standard and HP models were used. Postoperatively, patients were given subcutaneous heparin (5,000 U every 8 hours) until the INR or prothrombin time was therapeutic. For the first half of the study the prothrombin time was used and therapeutic target was 1.5 times control. A shift was then gradually made to INR with a target range of 1.8 to 2.5. Later aspirin (81 mg daily) was added to the regimen.
|
Results
|
|---|
Of 2,390 patients having aortic valve replacement 271 patients aged 18 to 50 had isolated aortic valve replacement with the SJM prosthesis. The mean age was 40 years and 75% were male. Nine procedures (3%) were reoperations. Mortality during the operative period was 1.1%. Valve-related events and mortality related to these events and linearized rates of events in percent per patient year as well as mortality for these events are shown in Table 2
and discussed in the following sections. Freedom from mentality is shown in Figure 1.
Mortality associated with valve-related events is discussed below.
View larger version (8K):
[in this window]
[in a new window]
|
Fig 1. Freedom from all mortality in patients having aortic valve replacement with the St. Jude Medical prosthesis followed up for as long as 20 years (n = patients at risk).
|
|
Anticoagulant-related hemorrhage occurred in 6 patients.
Two patient deaths were related to cerebrovascular bleeding and gastrointestinal bleeding. Thus in over 20 years there is a less than 1% mortality from valve-related events. Freedom from anticoagulant-related hemorrhage related to gastrointestinal bleeding or cerebrovascular bleeding is shown in Figure 3.
View larger version (11K):
[in this window]
[in a new window]
|
Fig 2. Freedom from anticoagulant-related bleeding in patients having aortic valve replacement with the St. Jude Medical prosthesis followed up for as long as 20 years (n = patients at risk).
|
|
View larger version (15K):
[in this window]
[in a new window]
|
Fig 3. Freedom from cerebrovascular (diamonds) or gastrointestinal (squares) anticoagulant-related bleeding events in patients having aortic valve replacement with the St. Jude Medical prosthesis and followed for up to 20 years (n = patients at risk).
|
|
Thromboembolic events occurred in 6 patients (2%). Three events were permanent and 3 were transient. There was no mortality related to these events. Freedom from thromboembolism is shown in Figure 4.
View larger version (10K):
[in this window]
[in a new window]
|
Fig 4. Freedom from thromboembolism (TE) in patients having aortic valve replacement with the St. Jude Medical prosthesis and followed up for as long as 20 years (n = patients at risk).
|
|
Paravalvular leak occurred in 6 patients. Two required reimplantation, 4 had repair. Two patients died after reoperation and represent a 20-year mortality of 1% for this event. Native valve endocarditis was a common etiology of paravalvular leak. Prosthetic valve endocarditis developed in 3 patients and they were treated medically. There was no mortality related to the prosthetic valve endocarditis. Valve thrombosis occurred in 2 patients, each 4 months postoperative, and each had valve re-replacement. There was no mortality related to this event.
Structural failure did not occur. Freedom from mechanical failure for the SJM aortic prosthesis in young patients for longer than 20 years was 100%.
|
Comment
|
|---|
During as long as 20 years of follow-up for patients 18 to 50 years of age, the SJM prostheses have performed exceedingly well. The morbidity rate of valve-related complications was 1.5%. An additional 1.5% of patients (2 with paravalvular leak and 2 with prosthetic valve endocarditis) underwent valve replacement, a much lower incidence than that for replacement of bioprosthetic valves as demonstrated by Khan and colleagues [7] who reported a valve bioprosthetic failure rate of more than 50% at 20 years, confirming the previous reports of Grunkemeier and colleagues [8].
As suggested by this latter group, patient-related factors greatly influence valve-related events. Our study group had minimal risk factors for valve-related events and all events occurred at an incidence of less than 0.3 per patient year. It is interesting that all thromboembolism events during the study period occurred early rather than being linear events. This is markedly less than the occurrence of valve-related events in our recently reported total series of patients having aortic valve replacement with the SJM valve [9].
As compared with the general population of aortic valve replacement patients, anticoagulant-related hemorrhage remained a common complication in this group and accounted for 50% of the valve-related mortality.
Figure 5 represents cumulative hazard events in the study group. Thromboembolism was as common but events were more minor and there were no event-related deaths. This finding may indicate INR could be further lowered. Recent approval and results of home testing of this self-administered test would indicate that an even lower valve-related events rate can be achieved by better maintaining patients in the therapeutic range [10]. Importantly, 90% of operative survivors were having INR checks at monthly intervals or less when contacted. There is limited inconvenience, which would be further reduced by home testing. Ezckowitz [11] has noted that chronic anticoagulation does not interfere with quality of life and younger patients can certainly be expected to be able within reason to lead a fully active lifestyle with a mechanical valve in place.
View larger version (15K):
[in this window]
[in a new window]
|
Fig 5. Cumulative hazard rates for mortality (triangles) and comorbid valve-related events, thromboembolism (diamonds), and anticoagulant-related hemorrhage (squares) in patients having aortic valve replacement with the St. Jude Medical prosthesis followed up for as long as 20 years.
|
|
In conclusion the SJM heart valve presents a record of excellent performance over long-term follow-up with minimal occurrence of untoward events. There has been no structural failure. The reliability of this device coupled with the low incidence of valve-related events indicates the device to be an excellent choice for younger patients requiring aortic valve replacement. Figure 2
|
References
|
|---|
- Cosgrove D.M. Aortic valve repair—key references. Ann Thorac Surg 1992;54:1014-1015.[Medline]
- Banbury M.K., Cosgrove D.M., III, White J.A., Blackstone E.H., Frater R.W.M., Okies J.E. Age and valve size effect on the long-term durability of the Carpentier-Edwards aortic pericardial bioprosthesis. Ann Thorac Surg 2001;72:753-757.[Abstract/Free Full Text]
- Emery R.W., Lindsay W.G., Anderson R.W., Jorgensen C.R., Wang Y., Nicoloff D.M. Clinical and hemodynamic results with the St. Jude Medical aortic valve prosthesis. Surg Forum 1979;30:235-238.[Medline]
- Grunkmeier G., Wu Y.X., Ruyun J. Statistical analysis of heart valve outcomes. J Heart Valve Dis 2002;11(Suppl 1):S2-S27.
- Cabalka A.K., Emery R.W., Petersen R.J., et al. Long term follow-up of the St. Jude Medical prosthesis in pediatric patients. Ann Thorac Surg 1995;60:S618-S623.
- Edmunds L.H., Jr, Cohn L.H., Weisel R.D. Guidelines for reporting morbidity and mortality after cardiac valvular operations. J Thorac Cardiovasc Surg 1988;96:351-353.[Medline]
- Khan S., Trento A., DeRobertis M., et al. Twenty year comparison of tissue and mechanical valve replacement. J Thorac Cardiovasc Surg 2001;122:257-269.[Abstract/Free Full Text]
- Starr A., Rahimtoola S. Prosthetic heart valve performances long term follow-up. Curr Probl Cardiol 1992;17:363.
- Emery R.W., Arom K.V., Kshettry V.R., et al. Decision-making in the choice of heart valve for replacement in patients aged 60–70 years: twenty-year follow up of the St. Jude Medical aortic valve prostheses. J Heart Valve Dis 2002;11(Suppl):S37-S44.
- Horstcotte D, Piper C, Wiener X, et al. Improvement of prognosis by home control in patients with life long anticoagulant therapy. Ann Hematol 1996;72(Suppl D):AE3
- Ezekowitz M.D. Anticoagulation management of valve replacement patients. J Heart Valve Dis 2002;11(Suppl 1):S56-S60.
Top
Abstract
Introduction
