Impact of coronary artery bypass grafting on survival after aortic valve replacement
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《血管的通路杂志》
a Division of Cardiac, Vascular and Thoracic Surgery, Royal Victoria Hospital, Grosvenor Road, Belfast, BT12 6BA, UK
b Department of Epidemiology and Public Health, Queen's University Belfast, UK
Abstract
Treatment of coronary artery disease by coronary artery bypass grafting (CABG) concurrently with aortic valve replacement (AVR) improves outcome but survival compared to isolated AVR remains uncertain, as does the role of the left internal mammary artery (LIMA) graft to the left anterior descending (LAD) artery. All 799 patients undergoing elective primary AVR, using the St. Jude Medical mechanical prosthesis, with or without CABG, between March 1986 and May 2000, were reviewed with 100% follow-up. Operative mortality was 1.6% in 574 patients undergoing isolated AVR, 2.6% in 78 patients undergoing combined AVR and CABG with LIMA to LAD grafting (LIMA-AVR), 6.25% in 64 patients receiving vein grafts only to circumflex or right coronary artery territories (Non-LAD VG-AVR) and 2.4% in 83 patients receiving vein grafts to vessels including the LAD (LAD VG-AVR). Cox regression analysis showed improved survival after AVR compared to LAD VG-AVR (P=0.008), but with no significant difference to survival after LIMA-AVR (P=0.18) and Non-LAD VG-AVR (P=0.08). Multivariable regression analysis identified advanced age (P<0.001), male sex (P<0.001), absence of diabetes (P=0.02), number of grafts performed during surgery (P=0.04), non-congenital valvular pathology (P=0.001) and regurgitant valve disease (P=0.008) as independent predictors of reduced survival. LIMA-LAD grafting was not a significant variable in the multivariable model.
Key Words: Aortic valve replacement; CABG surgery; Heart valve replacement; Survival analysis
1. Introduction
Coronary artery disease has a detrimental effect on long-term survival in patients undergoing aortic valve replacement [1]. Treatment of coronary artery disease by coronary artery bypass grafting (CABG) at the time of aortic valve replacement (AVR) improves long-term survival with acceptable morbidity and mortality [2,3].
Survival following CABG and AVR (CABG-AVR) is often assumed to be lower than following isolated AVR, but this remains controversial [4]. Use of the left internal mammary artery (LIMA) to left anterior descending artery (LAD) graft is beneficial in isolated coronary artery disease and improves long term survival [5]. It is unclear if use of the LIMA to LAD graft in combined AVR and CABG affects operative mortality or long-term survival. There is a theoretical risk that low flow syndrome in the early post-operative period would contribute to higher operative mortality, particularly in the setting of left ventricular hypertrophy, but this was not demonstrated in a retrospective study [6]. Moreover, this study suggested an improved long term survival in patients who received a LIMA to LAD graft, compared to those who received vein grafts only, during combined AVR and CABG.
Given the paucity of reports on these issues, we reviewed our experience to assess the overall influence of performing combined AVR and CABG compared to isolated AVR. In addition, we reviewed the influence of the LIMA to LAD graft on operative mortality and late survival following combined CABG and AVR.
2. Patients and methods
Seven hundred and ninety-nine patients (509 male, 290 female) undergoing elective primary AVR, using the St. Jude Medical mechanical prosthesis, with or without CABG between March 1986, when LIMA was first used in CABG-AVR, and May 2000 were retrospectively reviewed. Of 225 patients undergoing combined CABG-AVR, LIMA to LAD grafting was used in 78 patients (LIMA-AVR), while saphenous vein grafts only were used in 145 patients. Of these patients 64 underwent saphenous vein grafting to circumflex or right coronary artery territories (Non-LAD VG-AVR), while 83 patients had saphenous vein grafts to territories including the LAD (LAD VG-AVR). Any additional grafts in both groups were of saphenous vein. Cold hyperkalaemic cardioplegic arrest was used routinely for myocardial protection. Any patient who died within 30 days of operation, or in the hospital prior to discharge, was considered to have had an operative mortality. All patients were anticoagulated with warfarin, with a target international normalised ratio (INR) of 2.0–3.0, or 2.0–2.5 from 1992 onwards, in response to published data suggesting a reduction in haemorrhagic events without an increase in thromboembolic complications for isolated aortic mechanical prostheses [7].
Complete 100% follow-up was achieved (closing interval 224 days). Data for deceased patients were obtained from hospital and family physicians' records as well as from death certificates obtained from the Statistics and Research Agency of Northern Ireland.
Statistical analysis was performed with SPSS 12 (SPSS Inc, Chicago, IL). Chi-squared and Mann–Whitney U-tests, and ANOVA were used, as appropriate, to compare variables between groups. Kaplan–Meier log rank survival and Cox proportional hazard analyses were performed.
3. Results
Demographic and preoperative variables in the three groups (AVR only, n=574; LIMA-AVR, n=78; Non-LAD VG-AVR, n=64; LAD VG-AVR, n=83) are shown in Table 1. As expected, the mean age of patients who underwent AVR only was lower than for CABG-AVR, but among the latter, mean age of patients in the VG-AVR group was older than the LIMA-AVR group. There was a higher proportion of diabetics in the LIMA-AVR group compared to the other groups. The distribution of coronary artery bypass grafts differed among the groups, with obviously no grafts being performed in the isolated AVR group and fewer grafts being performed in patient who did not receive a graft to the LAD territory. There was also variation among the groups with respect to the haemodynamic nature of the valve lesion with stenoses being more common in the CABG-AVR groups compared to the isolated AVR only. Non-congenital valvular pathology occurred with higher incidence in the CABG-AVR groups compared to the isolated AVR group. In order to yield interpretable results all patients had received bileaflet mechanical valves, thus eliminating any effect which bioprostheses, and their associated degenerative failure with time, could have on long-term survival.
Operative mortality was 1.6% (9/574) in AVR, 2.6% (2/78) in LIMA-AVR, 6.25% (4/64) in Non-LAD VG-AVR and 2.4% (2/83) in LAD VG-AVR. Cox regression analysis showed that survival after AVR was better than after LAD VG-AVR (P=0.008), but was not significantly different to survival after LIMA-AVR (P=0.18) and Non-LAD VG-AVR (P=0.08) (Fig. 1).
The numbers 471 and 160 indicate the number of patients at risk at 5 years and 10 years, respectively. Long-term survival after AVR was better than after LAD VG-AVR (P=0.008), but it was not significantly different to survival after LIMA-AVR (P=0.18) or Non-LAD VG-AVR (P=0.08).
However, as indicated above, there were differences among the patient populations in each group. Multivariable regression analysis showed that advanced age (P<0.001), male sex (P<0.001), absence of diabetes (P=0.02), number of grafts performed during surgery (P=0.04), non-congenital valvular pathology (P=0.001) and regurgitant valve disease (P=0.008) were independent predictors of reduced survival (Table 2). LIMA-LAD grafting was not a significant explanatory variable in the multivariable model.
4. Comment
Survival of patients who underwent isolated AVR was better than for patients who underwent vein grafting of the LAD at the time of AVR. However, this was not found for patients who underwent LIMA to LAD grafting at the time of AVR, or for patients who had circumflex or right coronary artery grafting but not LAD grafting during CABG at the time of AVR. This possibility of improved long term survival associated with use of the LIMA to LAD graft, compared to the vein grafting, in combined AVR-CABG has been suggested previously, in studies with a shorter long term follow-up than the current report [6,8]. The study by Gall and co-workers did not consider patients who underwent isolated AVR without CABG, and thus could only compare patients who underwent concomitant CABG and AVR, with or without the use of the LIMA [6]. The study by Tribouilloy and co-workers showed that use of the LIMA to LAD graft was not an independent predictor of long-term survival, although overall survival in that cohort of patients was better than for patients who received vein grafts only, which bears similarity to the current report [8]. Therefore, it seems that while there may be good logic in utilising the LIMA to LAD graft, from experience gained in patients undergoing isolated CABG, there is no proof as yet of clinical benefit in terms of enhanced long-term survival with this policy in patients who undergo combined AVR and CABG [5].
Operative mortality was similar among the groups and, in particular, was exceptionally low at 2.6% and 2.4% in patients who received a LIMA graft or vein graft to the LAD, respectively. Thus, concern over the ability of a LIMA graft to deliver sufficient blood to the myocardium in patients undergoing AVR, is not borne out in this study.
The presence of coronary artery disease has been shown to result in reduced long-term survival following AVR compared to patients who do not have coronary artery disease [1]. Many reports suggest that concomitant CABG negates the effect of coronary artery disease on long-term survival [10,11]. However, in the current retrospective analysis of patients undergoing primary elective AVR with or without CABG, the number of grafts performed, which was obviously none in the group of isolated AVR patients, had predictive power in the multivariable analysis of long-term survival. This was similar to the findings of Tribouilloy and co-workers, who also found that concomitant CABG during AVR was an independent predictor of impaired long-term survival compared to isolated AVR [8]. It would thus seem that there is still debate over the extent to which treated coronary artery disease influences survival following AVR.
There were a number of factors that were independent predictors of long-term survival following AVR with or without concomitant CABG. Advanced age was, not unsurprisingly, associated with worse long-term survival [10,11]. Male sex was also associated with worse long-term survival which contrasts with the findings of other reports which showed that females had a worse outcome [10,11]. The finding that absence of diabetes was associated with a worse prognosis was an unexpected finding, which may be related to a high incidence of diabetics in the LIMA-AVR group compared to the isolated AVR group. Non-congenital versus congenital valvular pathology was related to a worse long-term outcome, which again may be related to a higher proportion of congenital valvular disease in the isolated AVR group compared to the combined AVR and CABG groups. The presence of aortic stenosis was associated with a better long-term survival compared to regurgitation or mixed disease. Aortic stenosis occurred with greater frequency in the CABG-AVR groups, especially in the LIMA-AVR group, which are a heterogenous group of patients. There are those patients with severe aortic stenosis who require concomitant CABG, but there is another group of patients with predominant CAD who have mild aortic stenosis which may benefit from AVR [12]. Ventricular function and the severity of the aortic valve lesion could not be ascertained accurately from the retrospective records. It is thus unclear if this improved outcome is actually related to patients with mild aortic valve disease and predominantly coronary artery disease, rather than the effect of either stenosis or regurgitation on ventricular function, and therefore, on survival. The haemodynamic nature of the valvular lesion was not found to be significant by other investigators [9,10,13].
In conclusion, patients who underwent isolated AVR had a better prognosis than patients in whom a vein graft was anastomosed to the LAD but survival was not significantly different to patients who had a LIMA graft to the LAD or who did not require grafting of the LAD. However, use of the LIMA versus vein graft to the LAD was not an explanatory variable in multivariable analysis of 14-year survival following AVR and CABG. Operative mortality of patients who received a LIMA graft to the LAD was similar to that of patients who received a vein graft to the LAD during AVR. Independent predictors of impaired survival were advanced age, male sex, absence of diabetes, non-congenital valvular pathology and regurgitant or mixed valve disease. Interestingly the number of grafts performed was an independent predictor of survival showing that patients with treated coronary artery disease at the time of AVR have a worse prognosis than patients requiring isolated AVR.
The findings from this institutional retrospective review are interesting and show that the need for performing CABG at the time of AVR results in a poorer long-term survival. The role of the LIMA to LAD graft in enhancing survival in the setting of isolated CABG is secure [5]. In the cohort of patients who require combined AVR and CABG, the LIMA to LAD graft was suggested to be beneficial by Gall and co-workers [6], but this was not confirmed by Tribouilloy and co-workers [8] nor in the current study by multivariable analysis. In clinical practice, it seems justified to use a LIMA when grafting the LAD graft, but any survival advantage is likely to be small especially in the setting of single or double vessel coronary artery disease.
Acknowledgements
We thank St. Jude Medical for providing a partial salary for Deidre Lovell, who undertook the telephone questionnaires and patient follow-up.
References
Copeland JG, Griepp RB, Stinson EB, Shumway NE. Long term follow-up after isolated aortic valve replacement. J Thorac Cardiovasc Surg 1977; 74:875–889.
Kouchoukous NT, Lell WA, Rogers WJ. Combined aortic valve replacement and myocardial revascularisation. Ann Thorac Surg 1983; 197:721–727.
Lund O, Nielsen TT, Pilegaard HK, Magnussen K, Knudsen MA. The influence of coronary artery disease and bypass grafting on early and late survival after valve replacement for aortic stenosis. J Thorac Cardiovasc Surg 1990; 100:327–337.
Mullany CJ, Elveback LR, Frye RL, Pluth JR, Edwards WD, Orszulak TA, Nassef LA Jr, Riner RE, Danielson GK. Coronary artery disease and its management: influence on survival in patients undergoing aortic valve replacement. J Am Coll Cardiol 1987; 10:66–72.
Loop FD, Lytle BW, Cosgrove DM, Stewart RW, Goormastic M, Williams GW, Golding LA, Gill CC, Taylor PC, Sheldon WC, Proudfit WL. Influence of the internal-mammary-artery graft on 10-year survival and other cardiac events. N Engl J Med 1986; 314:1–6.
Gall S, Lowe JE, Wolfe WG, Oldham HN, Van Trigt P III, Glower DD. Efficacy of the internal mammary artery in combined aortic valve replacement-coronary artery bypass grafting. Ann Thorac Surg 2000; 69:524–530.
Ibrahim M, O'Kane H, Cleland J, Gladstone D, Sarsam M, Patterson C. The St. Jude medical prosthesis: a 13 year experience. J Thorac Cardiovas Surg 1994; 108:221–230.
Tribouilloy CM, Enriquez-Sarano M, Schaff HV, Orszulak TA, Fett SL, Bailey KR, Tajik AJ, Frye RL. Excess mortality due to coronary artery disease after valve surgery. Secular trends in valvular regurgitation and effect of internal mammary artery bypass. Circulation 10 1998; 98:19 SupplII108–115.
Nunley DL, Grunkemeier GL, Starr A. Aortic valve replacement with coronary bypass grafting. Significant determinants of ten-year survival. J Thorac Cardiovasc Surg 1983; 85:705–711.
He GW, Grunkemeier GL, Starr A. Aortic valve replacement in elderly patients: influence of concomitant coronary grafting on late survival. Ann Thorac Surg 1996; 61:1746–1751.
Flameng WJ, Herijgers P, Szecsi J, Sergeant PT, Daenen WJ, Scheys I. Determinants of early and late results of combined valve operations and coronary artery bypass grafting. Ann Thorac Surg 1996; 61:621–628.
Ahmed AA, Graham AN, Lovell D, O'Kane HO. Management of mild to moderate aortic valve disease during coronary artery bypass grafting. Eur J Cardiothorac Surg 2003; 24:535–539.
Akins CW, Hilgenderg AD, Vlahakes GJ, MacGillivray TE, Torchiana DF, Madsen JC. Results of bioprosthetic versus mechanical aortic valve replacement performed with concomitant coronary artry bypass grafting. Ann Thorac Surg 2002; 74:1098–1106.(J. Mark Jones, Deidre Lov)
b Department of Epidemiology and Public Health, Queen's University Belfast, UK
Abstract
Treatment of coronary artery disease by coronary artery bypass grafting (CABG) concurrently with aortic valve replacement (AVR) improves outcome but survival compared to isolated AVR remains uncertain, as does the role of the left internal mammary artery (LIMA) graft to the left anterior descending (LAD) artery. All 799 patients undergoing elective primary AVR, using the St. Jude Medical mechanical prosthesis, with or without CABG, between March 1986 and May 2000, were reviewed with 100% follow-up. Operative mortality was 1.6% in 574 patients undergoing isolated AVR, 2.6% in 78 patients undergoing combined AVR and CABG with LIMA to LAD grafting (LIMA-AVR), 6.25% in 64 patients receiving vein grafts only to circumflex or right coronary artery territories (Non-LAD VG-AVR) and 2.4% in 83 patients receiving vein grafts to vessels including the LAD (LAD VG-AVR). Cox regression analysis showed improved survival after AVR compared to LAD VG-AVR (P=0.008), but with no significant difference to survival after LIMA-AVR (P=0.18) and Non-LAD VG-AVR (P=0.08). Multivariable regression analysis identified advanced age (P<0.001), male sex (P<0.001), absence of diabetes (P=0.02), number of grafts performed during surgery (P=0.04), non-congenital valvular pathology (P=0.001) and regurgitant valve disease (P=0.008) as independent predictors of reduced survival. LIMA-LAD grafting was not a significant variable in the multivariable model.
Key Words: Aortic valve replacement; CABG surgery; Heart valve replacement; Survival analysis
1. Introduction
Coronary artery disease has a detrimental effect on long-term survival in patients undergoing aortic valve replacement [1]. Treatment of coronary artery disease by coronary artery bypass grafting (CABG) at the time of aortic valve replacement (AVR) improves long-term survival with acceptable morbidity and mortality [2,3].
Survival following CABG and AVR (CABG-AVR) is often assumed to be lower than following isolated AVR, but this remains controversial [4]. Use of the left internal mammary artery (LIMA) to left anterior descending artery (LAD) graft is beneficial in isolated coronary artery disease and improves long term survival [5]. It is unclear if use of the LIMA to LAD graft in combined AVR and CABG affects operative mortality or long-term survival. There is a theoretical risk that low flow syndrome in the early post-operative period would contribute to higher operative mortality, particularly in the setting of left ventricular hypertrophy, but this was not demonstrated in a retrospective study [6]. Moreover, this study suggested an improved long term survival in patients who received a LIMA to LAD graft, compared to those who received vein grafts only, during combined AVR and CABG.
Given the paucity of reports on these issues, we reviewed our experience to assess the overall influence of performing combined AVR and CABG compared to isolated AVR. In addition, we reviewed the influence of the LIMA to LAD graft on operative mortality and late survival following combined CABG and AVR.
2. Patients and methods
Seven hundred and ninety-nine patients (509 male, 290 female) undergoing elective primary AVR, using the St. Jude Medical mechanical prosthesis, with or without CABG between March 1986, when LIMA was first used in CABG-AVR, and May 2000 were retrospectively reviewed. Of 225 patients undergoing combined CABG-AVR, LIMA to LAD grafting was used in 78 patients (LIMA-AVR), while saphenous vein grafts only were used in 145 patients. Of these patients 64 underwent saphenous vein grafting to circumflex or right coronary artery territories (Non-LAD VG-AVR), while 83 patients had saphenous vein grafts to territories including the LAD (LAD VG-AVR). Any additional grafts in both groups were of saphenous vein. Cold hyperkalaemic cardioplegic arrest was used routinely for myocardial protection. Any patient who died within 30 days of operation, or in the hospital prior to discharge, was considered to have had an operative mortality. All patients were anticoagulated with warfarin, with a target international normalised ratio (INR) of 2.0–3.0, or 2.0–2.5 from 1992 onwards, in response to published data suggesting a reduction in haemorrhagic events without an increase in thromboembolic complications for isolated aortic mechanical prostheses [7].
Complete 100% follow-up was achieved (closing interval 224 days). Data for deceased patients were obtained from hospital and family physicians' records as well as from death certificates obtained from the Statistics and Research Agency of Northern Ireland.
Statistical analysis was performed with SPSS 12 (SPSS Inc, Chicago, IL). Chi-squared and Mann–Whitney U-tests, and ANOVA were used, as appropriate, to compare variables between groups. Kaplan–Meier log rank survival and Cox proportional hazard analyses were performed.
3. Results
Demographic and preoperative variables in the three groups (AVR only, n=574; LIMA-AVR, n=78; Non-LAD VG-AVR, n=64; LAD VG-AVR, n=83) are shown in Table 1. As expected, the mean age of patients who underwent AVR only was lower than for CABG-AVR, but among the latter, mean age of patients in the VG-AVR group was older than the LIMA-AVR group. There was a higher proportion of diabetics in the LIMA-AVR group compared to the other groups. The distribution of coronary artery bypass grafts differed among the groups, with obviously no grafts being performed in the isolated AVR group and fewer grafts being performed in patient who did not receive a graft to the LAD territory. There was also variation among the groups with respect to the haemodynamic nature of the valve lesion with stenoses being more common in the CABG-AVR groups compared to the isolated AVR only. Non-congenital valvular pathology occurred with higher incidence in the CABG-AVR groups compared to the isolated AVR group. In order to yield interpretable results all patients had received bileaflet mechanical valves, thus eliminating any effect which bioprostheses, and their associated degenerative failure with time, could have on long-term survival.
Operative mortality was 1.6% (9/574) in AVR, 2.6% (2/78) in LIMA-AVR, 6.25% (4/64) in Non-LAD VG-AVR and 2.4% (2/83) in LAD VG-AVR. Cox regression analysis showed that survival after AVR was better than after LAD VG-AVR (P=0.008), but was not significantly different to survival after LIMA-AVR (P=0.18) and Non-LAD VG-AVR (P=0.08) (Fig. 1).
The numbers 471 and 160 indicate the number of patients at risk at 5 years and 10 years, respectively. Long-term survival after AVR was better than after LAD VG-AVR (P=0.008), but it was not significantly different to survival after LIMA-AVR (P=0.18) or Non-LAD VG-AVR (P=0.08).
However, as indicated above, there were differences among the patient populations in each group. Multivariable regression analysis showed that advanced age (P<0.001), male sex (P<0.001), absence of diabetes (P=0.02), number of grafts performed during surgery (P=0.04), non-congenital valvular pathology (P=0.001) and regurgitant valve disease (P=0.008) were independent predictors of reduced survival (Table 2). LIMA-LAD grafting was not a significant explanatory variable in the multivariable model.
4. Comment
Survival of patients who underwent isolated AVR was better than for patients who underwent vein grafting of the LAD at the time of AVR. However, this was not found for patients who underwent LIMA to LAD grafting at the time of AVR, or for patients who had circumflex or right coronary artery grafting but not LAD grafting during CABG at the time of AVR. This possibility of improved long term survival associated with use of the LIMA to LAD graft, compared to the vein grafting, in combined AVR-CABG has been suggested previously, in studies with a shorter long term follow-up than the current report [6,8]. The study by Gall and co-workers did not consider patients who underwent isolated AVR without CABG, and thus could only compare patients who underwent concomitant CABG and AVR, with or without the use of the LIMA [6]. The study by Tribouilloy and co-workers showed that use of the LIMA to LAD graft was not an independent predictor of long-term survival, although overall survival in that cohort of patients was better than for patients who received vein grafts only, which bears similarity to the current report [8]. Therefore, it seems that while there may be good logic in utilising the LIMA to LAD graft, from experience gained in patients undergoing isolated CABG, there is no proof as yet of clinical benefit in terms of enhanced long-term survival with this policy in patients who undergo combined AVR and CABG [5].
Operative mortality was similar among the groups and, in particular, was exceptionally low at 2.6% and 2.4% in patients who received a LIMA graft or vein graft to the LAD, respectively. Thus, concern over the ability of a LIMA graft to deliver sufficient blood to the myocardium in patients undergoing AVR, is not borne out in this study.
The presence of coronary artery disease has been shown to result in reduced long-term survival following AVR compared to patients who do not have coronary artery disease [1]. Many reports suggest that concomitant CABG negates the effect of coronary artery disease on long-term survival [10,11]. However, in the current retrospective analysis of patients undergoing primary elective AVR with or without CABG, the number of grafts performed, which was obviously none in the group of isolated AVR patients, had predictive power in the multivariable analysis of long-term survival. This was similar to the findings of Tribouilloy and co-workers, who also found that concomitant CABG during AVR was an independent predictor of impaired long-term survival compared to isolated AVR [8]. It would thus seem that there is still debate over the extent to which treated coronary artery disease influences survival following AVR.
There were a number of factors that were independent predictors of long-term survival following AVR with or without concomitant CABG. Advanced age was, not unsurprisingly, associated with worse long-term survival [10,11]. Male sex was also associated with worse long-term survival which contrasts with the findings of other reports which showed that females had a worse outcome [10,11]. The finding that absence of diabetes was associated with a worse prognosis was an unexpected finding, which may be related to a high incidence of diabetics in the LIMA-AVR group compared to the isolated AVR group. Non-congenital versus congenital valvular pathology was related to a worse long-term outcome, which again may be related to a higher proportion of congenital valvular disease in the isolated AVR group compared to the combined AVR and CABG groups. The presence of aortic stenosis was associated with a better long-term survival compared to regurgitation or mixed disease. Aortic stenosis occurred with greater frequency in the CABG-AVR groups, especially in the LIMA-AVR group, which are a heterogenous group of patients. There are those patients with severe aortic stenosis who require concomitant CABG, but there is another group of patients with predominant CAD who have mild aortic stenosis which may benefit from AVR [12]. Ventricular function and the severity of the aortic valve lesion could not be ascertained accurately from the retrospective records. It is thus unclear if this improved outcome is actually related to patients with mild aortic valve disease and predominantly coronary artery disease, rather than the effect of either stenosis or regurgitation on ventricular function, and therefore, on survival. The haemodynamic nature of the valvular lesion was not found to be significant by other investigators [9,10,13].
In conclusion, patients who underwent isolated AVR had a better prognosis than patients in whom a vein graft was anastomosed to the LAD but survival was not significantly different to patients who had a LIMA graft to the LAD or who did not require grafting of the LAD. However, use of the LIMA versus vein graft to the LAD was not an explanatory variable in multivariable analysis of 14-year survival following AVR and CABG. Operative mortality of patients who received a LIMA graft to the LAD was similar to that of patients who received a vein graft to the LAD during AVR. Independent predictors of impaired survival were advanced age, male sex, absence of diabetes, non-congenital valvular pathology and regurgitant or mixed valve disease. Interestingly the number of grafts performed was an independent predictor of survival showing that patients with treated coronary artery disease at the time of AVR have a worse prognosis than patients requiring isolated AVR.
The findings from this institutional retrospective review are interesting and show that the need for performing CABG at the time of AVR results in a poorer long-term survival. The role of the LIMA to LAD graft in enhancing survival in the setting of isolated CABG is secure [5]. In the cohort of patients who require combined AVR and CABG, the LIMA to LAD graft was suggested to be beneficial by Gall and co-workers [6], but this was not confirmed by Tribouilloy and co-workers [8] nor in the current study by multivariable analysis. In clinical practice, it seems justified to use a LIMA when grafting the LAD graft, but any survival advantage is likely to be small especially in the setting of single or double vessel coronary artery disease.
Acknowledgements
We thank St. Jude Medical for providing a partial salary for Deidre Lovell, who undertook the telephone questionnaires and patient follow-up.
References
Copeland JG, Griepp RB, Stinson EB, Shumway NE. Long term follow-up after isolated aortic valve replacement. J Thorac Cardiovasc Surg 1977; 74:875–889.
Kouchoukous NT, Lell WA, Rogers WJ. Combined aortic valve replacement and myocardial revascularisation. Ann Thorac Surg 1983; 197:721–727.
Lund O, Nielsen TT, Pilegaard HK, Magnussen K, Knudsen MA. The influence of coronary artery disease and bypass grafting on early and late survival after valve replacement for aortic stenosis. J Thorac Cardiovasc Surg 1990; 100:327–337.
Mullany CJ, Elveback LR, Frye RL, Pluth JR, Edwards WD, Orszulak TA, Nassef LA Jr, Riner RE, Danielson GK. Coronary artery disease and its management: influence on survival in patients undergoing aortic valve replacement. J Am Coll Cardiol 1987; 10:66–72.
Loop FD, Lytle BW, Cosgrove DM, Stewart RW, Goormastic M, Williams GW, Golding LA, Gill CC, Taylor PC, Sheldon WC, Proudfit WL. Influence of the internal-mammary-artery graft on 10-year survival and other cardiac events. N Engl J Med 1986; 314:1–6.
Gall S, Lowe JE, Wolfe WG, Oldham HN, Van Trigt P III, Glower DD. Efficacy of the internal mammary artery in combined aortic valve replacement-coronary artery bypass grafting. Ann Thorac Surg 2000; 69:524–530.
Ibrahim M, O'Kane H, Cleland J, Gladstone D, Sarsam M, Patterson C. The St. Jude medical prosthesis: a 13 year experience. J Thorac Cardiovas Surg 1994; 108:221–230.
Tribouilloy CM, Enriquez-Sarano M, Schaff HV, Orszulak TA, Fett SL, Bailey KR, Tajik AJ, Frye RL. Excess mortality due to coronary artery disease after valve surgery. Secular trends in valvular regurgitation and effect of internal mammary artery bypass. Circulation 10 1998; 98:19 SupplII108–115.
Nunley DL, Grunkemeier GL, Starr A. Aortic valve replacement with coronary bypass grafting. Significant determinants of ten-year survival. J Thorac Cardiovasc Surg 1983; 85:705–711.
He GW, Grunkemeier GL, Starr A. Aortic valve replacement in elderly patients: influence of concomitant coronary grafting on late survival. Ann Thorac Surg 1996; 61:1746–1751.
Flameng WJ, Herijgers P, Szecsi J, Sergeant PT, Daenen WJ, Scheys I. Determinants of early and late results of combined valve operations and coronary artery bypass grafting. Ann Thorac Surg 1996; 61:621–628.
Ahmed AA, Graham AN, Lovell D, O'Kane HO. Management of mild to moderate aortic valve disease during coronary artery bypass grafting. Eur J Cardiothorac Surg 2003; 24:535–539.
Akins CW, Hilgenderg AD, Vlahakes GJ, MacGillivray TE, Torchiana DF, Madsen JC. Results of bioprosthetic versus mechanical aortic valve replacement performed with concomitant coronary artry bypass grafting. Ann Thorac Surg 2002; 74:1098–1106.(J. Mark Jones, Deidre Lov)