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Ann Thorac Surg 1995;60:999-1006
© 1995 The Society of Thoracic Surgeons
St. Paul's Hospital and Vancouver Hospital and Health Sciences Centre, University of British Columbia, Vancouver, British Columbia, Canada
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Abstract |
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 TopFootnotes Abstract IntroductionMaterial and MethodsResultsCommentReferences |
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Methods. The ``Guidelines for Reporting Morbidity and Mortality After Cardiac Valvular Operations'' were used for definitions of valve-related complications, categorization, and statistical methods. The valve-related complications were evaluated in a time-related manner by actuarial life-table techniques. The Lee-Desu statistic test was used for comparison of performance by valve positions and age groups. Hazard function rates were demonstrated for complications and composites.
Results. Of the Carpentier-Edwards porcine bioprostheses implanted in 1,195 patients (1,214 operations, 1,315 valves) commencing in 1975 the early mortality was 7.6% (92). The early mortality without concomitant procedures was 6.1% and with 11.7%. The late mortality was 5.3% per patient-year; 4.6% patient-year without and 7.5% per patient-year with concomitant procedures. The valve-related causes of late mortality (131) were thromboembolism (41), antithromboembolic hemorrhage (14), prosthetic valve endocarditis (20), nonstructural dysfunction (12), and structural valve deterioration (44). The valve-related deaths (early, 7; late, 124) were 21.2% of the total 617 total deaths. Reoperation for valve-related complications was performed in 406 patients (4.1% per patient-year), of which 327 were for structural valve deterioration (3.3% per patient-year). Mortality for reoperation was 0.5% per patient-year (49 patients) or 12.1%. Of the 49 deaths, 33 were caused by structural valve deterioration. The linearized occurrence rate for thromboembolism was 1.6% per patient-year (major, 0.9% per patient-year, and minor, 0.7% per patient-year). The fatal thromboembolic rate was 0.4% per patient-year (41), undifferentiated by valve position. The freedom from thromboembolism was 76% at 17 years (p = not significant by valve position) (major, 87%; fatal, 93%). The freedom from prosthetic valve endocarditis was 92% at 17 years (p = not significant by valve position). The freedom from reoperation, at 15 years, was 38%: aortic (AVR), 55%; mitral (MVR), 20%; and multiple valve replacement (MR), 24% (p < 0.05 AVR > MVR, MR). The freedom from structural valve deterioration, at 15 years, was 41%; AVR, 58%; MVR, 21%; MR, 36% (p < 0.05 AVR > MVR, MR). The freedom from structural valve deterioration was greater for advancing age groups (p < 0.05); AVR 
70 years 96% at 12 years, and 65 to 69 years 94% at 12 years and 82% at 15 years; MVR 70 years 85% at 12 years, and 65 to 69 years 54% at 12 years. The freedom from valve-related mortality was 73% at 17 years: AVR, 80%; MVR, 61%; and MR, 67% (p < 0.05 AVR > MVR, MR). The freedom from valve-related residual morbidity was 94% (p = not significant by valve position).
Conclusions. The Carpentier-Edwards standard porcine bioprosthesis continues to provide satisfactory clinical performance to 17 years. Thromboembolism is a more serious problem than structural failure: 92 major thromboembolic events with 41 fatalities compared with 44 fatalities of which 33 occurred with reoperation. The prosthesis is especially recommended for patients more than 65 years of age for AVR and more than 70 years of age for MVR.
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Introduction |
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TopFootnotesAbstractIntroductionMaterial and MethodsResultsCommentReferences |
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Biological prostheses preserved with glutaraldehyde have been used for cardiac valve replacement since 1972. The porcine bioprostheses have provided patients an excellent quality of life with a low rate of serious thromboembolism, essential lack of thrombosis, and freedom from anticoagulant hemorrhage. The primary concern over the past decade with bioprostheses has been altered durability due to structural failure of the biological tissue, with calcification and stress-related fatigue injuries presented as tears and perforations with or without calcification. The Hancock standard prosthesis (Medtronic Inc, Irvine, CA) was introduced in 1971 and the Carpentier-Edwards standard prosthesis (Baxter Healthcare Corp, Edwards CVS Division, Irvine, CA) in 1975. Since 1982 several new second- and third-generation porcine bioprostheses have been introduced, namely, Carpentier-Edwards supraannular, Hancock II, Bicor, Medtronic Intact, St. Jude Bio-implant (formerly Liotta), and most recently the Medtronic Mosaic and the St. Jude Medical Hancock-Jaffe porcine bioprostheses.
The Carpentier-Edwards standard porcine bioprosthesis is an intraannular prosthesis with tissue fixation with glutaraldehyde at approximately 60 mm Hg pressure. Since the introduction of the prosthesis in 1975 there have been three design changes approved by the US Food and Drug Administration. In 1976 the stent was modified to improve the implantation characteristics of the sewing ring; in 1980 the standard annulus model was changed to the improved annulus by altering the wire form thickness to incorporate a larger porcine valve in the same prosthesis size especially in the smaller prosthesis. In 1982 an additional sterilant was incorporated, which reacted against a glutaraldehyde-resistant microorganism. This sterilant, surfactant polysorbate 80, has calcium mitigation properties. We were not able to evaluate the influence of the sterilant on degenerative processes because the vast majority of our implantations were performed before 1982.
The teaching hospitals of the University of British Columbia (St. Paul's Hospital and Vancouver Hospital and Health Sciences Centre) have a 20-year experience with porcine bioprostheses [1–8]. The Carpentier-Edwards prostheses have been implanted in approximately 3,900 patients, of whom 1,195 patients had the Carpentier-Edwards standard prosthesis and the remainder of the supraannular prosthesis. The standard Carpentier-Edwards porcine bioprosthesis was introduced in Canada in 1975 and the supraannular porcine bioprosthesis in 1981. The distribution of biological and mechanical prostheses implanted annually is shown in Figure 1
for the years 1975 through 1994. The teaching hospitals of the University of British Columbia have previously reported on the clinical performance of the Carpentier-Edwards standard prosthesis, including the 10- and 15-year experience [2, 4].
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Material and Methods |
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TopFootnotesAbstractIntroductionMaterial and MethodsResultsCommentReferences |
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The valve-related complications and composite indexes of these valve-related complications were evaluated in the time-related manner by actuarial life-table techniques (or Cutler-Ederer method). The Lee-Desu statistic was used to provide comparison of the complication-free curves of valve positions for each complication and complication-free curves of valve positions by age groups for structural failure (structural valve deterioration). Linearized occurrence rates (events per 100 patient-years or percent per patient-year) were not retained in this study, except for thromboembolism, because hazard function rates were not constant; hazard function rates are demonstrated by complication or composite of complications for the overall population.
Patients
The teaching hospitals of the University of British Columbia (St. Paul's Hospital, and Vancouver Hospital and Health Sciences Centre) commenced use of the Carpentier-Edwards standard porcine bioprosthesis in January 1975 and completed use in June 1986. Most of the prostheses were implanted by late 1981 and early 1982 when use of the Carpentier-Edwards supraannular porcine bioprosthesis was commenced.
The patient population receiving the Carpentier-Edwards standard porcine bioprosthesis is as follows: 1,195 patients received 1,315 prostheses in 1,214 operations. Aortic valve replacement (AVR) was performed in 573 patients, mitral valve replacement (MVR) in 501 patients, pulmonary valve replacement in 1, tricuspid valve replacement in 7, and multiple valve replacement (MR) in 113 patients. The male and female ratio distribution is 649 male patients and 546 female patients. Concomitant procedures, primarily coronary artery bypass and ascending aortic aneurysm resection, were performed in 325 patients or 26.8% of the total patient population; 155 patients or 12.8% had a previous cardiac operation. The patients, in general, received anticoagulation for 6 weeks to 3 months after valve replacement (AVR, MVR, and MR) and for long-term management in the presence of chronic atrial fibrillation with MVR and MR.
The mean age of the patient population is 57.3 years (range, 8 to 85 years); for AVR, 59.2 years; MVR, 56.1 years; and MR, 53.4 years. The cumulative follow-up was 9,968 years (AVR, 5,187; MVR, 3,877; MR, 850 years). The follow-up was 96% complete with 46 patients who were lost at final follow-up. The mean follow-up period was 8.2 years.
The patients were assessed by age groups: 35 years or less (101), 36 to 50 years (204), 51 to 64 years (506), 65 to 69 years (195), and 70 years or greater (208).
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Results |
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TopFootnotesAbstractIntroductionMaterial and MethodsResultsCommentReferences |
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, respectively. The valve-related causes of early mortality were thromboembolism (2), antithromboembolic therapy hemorrhage (1), prosthetic valve endocarditis (2), and nonstructural dysfunction (periprosthetic leak, 2). The early mortality of 7.6% (92) was influenced by concomitant procedures, 11.7% (38) with and 6.1% (54) without concomitant procedures.
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. The valve-related causes of early and late mortality were thromboembolism (41), antithromboembolic therapy-related hemorrhage (14), prosthetic valve endocarditis (20), nonstructural dysfunction (12), and structural valve deterioration (44). The linearized occurrence rate for valve-related mortality was 1.3% per patient-year (131). The overall and position patient survival including operative deaths are shown in Fig 2. The 131 valve-related deaths (early, 7; late, 124) were 21.2% of the 617 total deaths.
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. Reoperation for valve-related complications was performed in 406 patients (4.1% per patient-year) (13 patients who had MR had double reoperation reasons, 1.5% per patient-year). The valve-related reoperation rate was for thromboembolic phenomena, 0.04% per patient-year (4); prosthetic valve endocarditis, 0.4% per patient-year (35); nonstructural dysfunction, 0.4% per patient-year (40) and structural valve deterioration, 3.3% per patient-year (327). Fatality for reoperation was 0.5% per patient-year (49 patients) or 12.1%. Of the 49 patients, the number having each complication was 33 for structural valve deterioration, 6 for prosthetic valve endocarditis, 8 for nonstructural dysfunction, and 2 for thromboembolism.
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. The overall linearized occurrence rate for major events was 0.9% per patient-year. The overall linearized occurrence rate for minor events was 0.7% per patient-year. The linearized occurrence rates for major and minor thromboembolism by valve position are shown in Table 4. Fatality overall was 0.4% per patient-year and by valve position as follows: AVR, 0.4% per patient-year; MVR, 0.5% per patient-year; and MR, 0.5% per patient-year. Of the patients who experienced thromboembolism, 9 of 76 patients receiving AVR (11.8%) and 7 of 75 patients having MVR (9.3%) were receiving anticoagulation at the final follow-up.
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The freedom from individual valve-related complications is shown in Figures 3 through 6 and 11 through 16, whereas composites of valve-related complications are shown in Figures 7 through 10. The linearized occurrence rates of each complication and composite, overall, by yearly hazard intervals are also illustrated for complications and composites. Freedom from each complication is depicted for the overall population and for AVR, MVR, and MR.
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). Freedom from structural valve deterioration overall at 15 years was 41.3% ± 2.8%. Freedom at the 15-year interval for AVR was 58.2% ± 4.0%; for MVR, 21.0% ± 3.9%; and for MR, 35.9% ± 7.9%. Freedom was significantly greater for AVR over MVR and MR (p < 0.05). Structural valve deterioration was identified at reoperation in the third year of observation, although most cases were managed between 11 and 17 years with intermediate numbers at 7 and 10 years. Most cases were due to fatigue lesions of tears and perforations with or without nonobstructing calcification, whereas the minority had obstructive calcification, primarily in the younger age groups.
The freedom from thromboembolism, overall, at 17 years was 75.6% ± 3.2% with no differentiation by valve position (p = not significant). The freedom from thromboembolism comparing major and fatal with overall is illustrated in Figure 4, with the hazard rates in Figure 5. The freedom from major thromboembolism at 17 years was 87.0% ± 2.4% for AVR, 86.8% ± 2.1% for MVR, and 91.7% ± 3.4% for MR (p < 0.05, AVR > MVR). The freedom from fatal thromboembolism at 17 years was 92.2% ± 2.2% for AVR, 94.4% ± 1.4% for MVR, and 94.2% ± 3.0% for MR (p = not significant). The freedom from antithromboembolic-related hemorrhage at 17 years was overall, 92.2% ± 1.9%; AVR, 97.8% ± 0.7%; MVR, 82.9% ± 5.9%; and MR, 85.5% ± 9.7% (p < 0.05, AVR > MVR).
The freedom from prosthetic valve endocarditis at 17 years was 91.8% ± 1.4% for the overall population, 93.3% ± 1.3% for AVR, and 93.4% ± 1.4% for MVR (p = not significant) (Fig 6). The hazard rates are minimal and cases occurred sporadically throughout the observation period. The freedom from nonstructural dysfunction at 17 years was overall, 98.4% ± 2.9%; AVR, 96.2% ± 1.1%; and MVR, 93.4% ± 1.8%. At 12 years the freedom from nonstructural dysfunction in the MR group was 72.6% ± 6.1% (p < 0.05, AVR > MVR > MR).
The multiple decrement analysis of valve-related complications is shown in Figures 7 through 10. Freedom from valve-related reoperation, illustrated in Figure 7, demonstrates that the freedom was greater for AVR over MVR and MR (p < 0.05). The overall freedom was 23.1% ± 4.2% at 17 years. The freedom from valve-related mortality at 17 years was 72.7% ± 3.3% overall (Fig 8). The freedom from mortality at 17 years was AVR, 80.1% ± 4.1%; MVR, 61.3% ± 6.2%; and MR, 66.9% ± 2.1% (p < 0.05, AVR > MVR, MR).
The freedom from valve-related residual morbidity (permanent impairment) was not different by valve positions (p = not significant) (Fig 9). The overall freedom was 93.8% ± 0.9% at 17 years. The freedom from all valve-related complications at 17 years was 15.2% ± 3.4%: AVR, 25.5% ± 6.3%; MVR, 4.2% ± 2.5%; and MR, 6.9% ± 4.9% (p < 0.05, AVR > MVR, MR) (Fig 10).
Figure 11 denotes the freedom from structural valve deterioration by age groups, inclusive of all valve positions. Greater freedom by advancing decades of life is observed. The freedom from structural valve deterioration for aortic valve replacement is illustrated in Figure 12. The freedom for the group 70 years of age or older was 95.6% ± 3.0% at 12 years, and for the group 65 to 69 years old, 93.6% ± 3.2% at 12 years and 81.5% ± 7.3% at 15 and 17 years (p < 0.05 70 years and older and 65 to 69 years > 51 to 64 years > 36 to 50 years and 35 years or less). The annual hazard rates are indicated in Figure 13.
The freedom from structural valve deterioration for mitral valve replacement by age groups is illustrated in Figure 14. The freedom for the age group 70 years and older was 91.5% ± 4.8% at 10 years and 84.8% ± 7.9% at 12 years. For the age groups 65 to 69 years and 51 to 64 years, the freedom at 12 years was 54.1% ± 8.3% and 55.1% ± 4.8%, respectively (p < 0.05 70 years and older > 36 to 69 years). The hazard rates are illustrated in Figure 15. The freedom from structural valve deterioration for multiple valve replacement is demonstrated in Figure 16.
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Comment |
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TopFootnotesAbstractIntroductionMaterial and MethodsResultsCommentReferences |
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Structural valve deterioration has become recognized as the predominant valve-related complication. In 1988 Jamieson and colleagues [1] documented that even though structural valve deterioration occurred at all ages, the freedom was greater with advancing decades of age. The failure modes have been identified as primary dystrophic calcifications or stress-related tears or perforations with or without the presence of calcification. Primary dystrophic calcification is a less common calcification in adults, occurring primarily in children and adolescents.
The long-term experience with the first-generation Hancock and Carpentier-Edwards porcine bioprostheses has been documented at various durations of evaluation [1–4, 6, 7, 10–16]. Comparison between reports, even at similar time intervals, is often not possible because of the different mean ages of the population groups. Bortolotti and co-authors [10] last reported on the University of Padova experience of the Hancock standard prosthesis in 1991, documenting a freedom at 18 years of 36% for aortic prostheses and 18% for mitral prostheses. This patient population is younger than other reported series, with a mean age of 47 years. The Stanford University experience with the Hancock standard and the University of British Columbia experience with the Carpentier-Edwards standard prostheses are more representative of valvular populations and comparable because of similar mean ages of 57 years. Burdon and associates [11] reported freedom at 10 and 15 years of 85% and 63%, respectively, for AVR and 78% and 45% for MVR. In 1990 Jamieson and colleagues [2] documented 10-year freedoms of 79% and 72% with Carpentier-Edwards aortic and mitral replacements, respectively, whereas in 1991 [4] 15-year freedoms of 71% and 41%, respectively, were seen for aortic and mitral replacements.
Other series have confirmed the clinical performance of standard porcine bioprostheses. In 1990 Jones and colleagues [12] reported 10-year freedom from structural failure with standard prostheses of 79% for AVR and 63% for MVR. Akins and co-authors [13], in 1990, reported better freedom from structural failure with the Carpentier-Edwards standard prostheses: 91% for aortic replacements and 75% for mitral replacements. Sarris and associates [14], in 1993, reported better freedom with the Carpentier-Edwards standard than the Hancock standard: 71% and 59%, respectively. Bernal and colleagues [15] also reported on the Hancock standard, in 1991, documenting structural failure freedom of 44% for aortic prostheses and 37% for mitral prostheses at 14 years.
The current report on the Carpentier-Edwards standard porcine bioprosthesis confirmed the previously documented 10-year performance of freedom from structural valve deterioration of 86% for aortic prostheses and 70% for mitral prostheses but reduced freedom at 15 years of 58% and 21%, respectively, and at 17 years of 39% and 14%, respectively [2, 4]. These freedoms are similar to the 18-year freedom from structural valve deterioration at a younger mean age reported for the Hancock prosthesis by Bortolotti and associates [10].
Since 1982 several second-generation porcine bioprostheses have been introduced. The first to be introduced was the Carpentier-Edwards supraannular porcine bioprosthesis with tissue fixation with glutaraldehyde at 2 mm Hg and antimineralization treatment with the surfactant agent polysorbate 80. The Hancock II prosthesis was subsequently introduced, fixed with glutaraldehyde at low pressure followed by high pressure and with the surfactant sodium dodecyl sulfate for calcium retardation. The newest prosthesis, the Medtronic Intact prosthesis, is an intraannular prosthesis, in comparison, with the tissue pressure-free fixed with glutaraldehyde and toluidine blue for calcium mitigation. The Biocor porcine bioprosthesis has tissue fixation with glutaraldehyde at a resting pressure of less than 1 mm Hg.
The question of major interest is whether these newer prostheses will contribute to reduction of structural valve deterioration. In 1991 the 8-year freedom from structural failure with the Carpentier-Edwards supraannular porcine bioprosthesis was documented as 86% for AVR and 73% for MVR [5]. In the same year, Jamieson and colleagues [6] reported a 7-year freedom comparison between the Carpentier-Edwards standard and supraannular porcine bioprostheses. The freedom from structural failure was not different between the prostheses: 96% for standard aortic and 98% for supraannular aortic and 89% for both standard and supraannular mitral. The standard population, as previously stated, had a mean age of 57 years, whereas the mean age for the supraannular population was 62.7 years. In 1994 Jamieson and co-authors [7] reported a 10-year comparison of the prostheses, which revealed a freedom from structural failure for AVR of 84% for standard prostheses and 87% for supraannular prostheses and for MVR, 69% and 75%, respectively. The overall freedom at 8 years from structural failure for the Hancock II valve was reported by David and colleagues [17] to be 93% for aortic prostheses and 83% for mitral prostheses. The age differences between the Hancock II and the Carpentier-Edwards supraannular porcine bioprosthesis populations does not provide the opportunity for clear differentiation between the prostheses. The Biocor porcine bioprostheses, as reported by Mykén and colleagues [18], had a 10-year freedom from reoperation for structural failure of 78%. The experience with the Medtronic Intact porcine bioprosthesis has had limited documentation. Barratt-Boyes and colleagues [19], in 1993, with a population with a mean age of 53 years, identified freedom of 100% for aortic prostheses and 80% for mitral prostheses. Munro and associates [8] revealed the freedom from structural failure with the Medtronic Intact prosthesis to be 97% for aortic prostheses at 8 years and 100% for mitral prostheses at 6 years in patients with a mean age of 67 years.
The greater freedom from structural failure for age groups of advancing years [1, 3] was again shown in the current documentation. The Carpentier-Edwards standard aortic prosthesis has provided a 96% freedom at 12 years for age group 70 years old and older, and at 12 years 94% and at 15 and 17 years 82% for the age group 65 to 69 years. The freedom for mitral replacements was 85% at 12 years for patients 70 years old and older, and 54% for those 65 to 69 years old. This experience confirms the previous recommendations for use of porcine bioprostheses. Pelletier and colleagues [16] demonstrated freedom of 93% and 92% for age groups between 65 and 80 years at 12 years.
The current study has revealed that thromboembolism was a more serious problem than structural failure. There were 92 major thromboembolic events with 41 fatalities. Structural valve deteriorations caused 44 fatalities, of which 33 occurred as a result of 327 reoperations.
The freedom from valve-related mortality was 75% at 15 years, 83% for AVR and 61% for MVR. The freedom from residual morbidity or permanent impairment was 94% at 15 years. This experience demonstrates satisfactory freedom from prosthesis-related mortality while contributing toward quality of life with minimal permanent impairment.
This experience can provide a standard for comparison of future bioprostheses with advanced technologies. The newer generation prostheses, with tissue preservation with glutaraldehyde, do not seem to provide a significant improvement in the occurrence of structural failure [6–8, 17, 19]. This study confirms that bioprostheses are recommended for patients more than 65 years of age for AVR and more than 70 years of age for MVR.
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Footnotes |
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TopFootnotesAbstractIntroductionMaterial and MethodsResultsCommentReferences |
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Address reprint requests to Dr Jamieson, Department of Surgery, University of British Columbia, 910 W 10th Ave, Rm 3100, Vancouver, BC, V5Z 4E3 Canada.
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