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Ann Thorac Surg 1999;68:1272-1277
© 1999 The Society of Thoracic Surgeons
a Division of Cardiothoracic Surgery, Department of Surgery, Washington University School of Medicine, St. Louis, Missouri, USA
Address reprint requests to Dr Sundt, Division of Cardiothoracic Surgery, Department of Surgery, Washington University School of Medicine, 3106 Queeny Tower, St. Louis, MO 63110
e-mail: sundtt{at}msnotes.wustl.edu
| Abstract |
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Methods. A search of our computerized database identified 7,096 patients undergoing myocardial revascularization between January 1, 1986 and March 30, 1997, of whom 177 (2.3%) underwent endarterectomy of at least one coronary artery. Perioperative events were derived from the database. Follow-up information was obtained from patients at 3 months to 11.5 years (mean = 55.7 ± 38.8 months) after surgery.
Results. Endarterectomy was performed on the right coronary artery (RCA) system in 100 patients, the left anterior descending (LAD) system in 52, the circumflex system in 18, and in multiple distributions in 7. The 30-day mortality was 7% for RCA, 0% for LAD, 17% for circumflex, and 14% for multi-system endarterectomy (p = 0.20). There were no statistically significant differences in perioperative myocardial infarction or ventricular dysrhythmia between these groups. Actuarial survival at 5 years was 76% for patients undergoing RCA endarterectomy and 75% for left sided (LAD or circumflex) endarterectomy (p = 0.91). At late follow-up, 74% (86/117) of survivors were angina-free, 6% (7/117) had undergone subsequent angioplasty, and 3% (4/117) had undergone subsequent surgery.
Conclusions. Coronary endarterectomy can be accomplished with acceptable operative risk and good long-term results, even when applied in a highly selective manner. The results of novel therapies for diffuse coronary artery disease should be considered in the context of those achievable with more traditional approaches.
| Introduction |
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Coronary endarterectomy was introduced for the treatment of atherosclerotic coronary artery disease over 4 decades ago [3, 4]; however, the success of coronary artery bypass grafting relegated it to a position of secondary importance. Although liberal use of endarterectomy is still advocated by a cadre of loyal enthusiasts [58], this approach is generally held to carry higher perioperative risk and yield poorer long-term results than bypass grafting alone [911]. Furthermore, there is some evidence that endarterectomy of the left anterior descending (LAD) is associated with a particularly high operative risk [9]. Endarterectomy, especially of the LAD, is therefore performed by most surgeons in a highly selective manner, and only when no alternatives exist.
The development of alternative therapies for otherwise unreconstructable coronary disease renews discussion of the risks and benefits of coronary endarterectomy, because surgeons now have options from which to choose. The literature on this subject is relatively sparse, particularly in the current decade [7, 8, 1113], and it is dominated by reports from centers in which endarterectomy is performed in a relatively high percentage (20%50%) of cases [57, 13]. In contrast, it is our practice to apply this technique in a highly selective manner to only those vessels that could not otherwise be bypassed. As subtleties of patient selection may have significant impact on results, we chose to examine our own experience with these high-risk patients in order to re-evaluate this technique as an alternative or supplement to novel therapies. Additionally, evidence of differences in risks and outcomes according to the coronary distribution endarterectomized were sought.
| Material and methods |
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Operative characteristics of patients undergoing endarterectomy are presented in Table 2. Although saphenous vein was most often used to reconstruct the endarterectomized vessel, the internal thoracic artery was used in half the cases involving the LAD. In the majority of these cases the LAD was reconstructed with a saphenous vein hood, to which the internal thoracic artery was then sewn. Associated procedures were carried out in 31 patients (18%), most of which were repair of a left ventricular aneurysm.
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All continuous data were expressed as the mean ± the standard deviation. Two-group comparisons for continuous data were made using the Students t test. Categorical data were tabulated, and two-group comparisons were made using the
2 test for 2 x n tables. When 2 x 2 tables were analyzed, Fishers exact test was used. The survival analysis was done using the Kaplan-Meier estimator. Comparisons were made using the Mantel log-rank test. The Cox proportional hazards model was used to examine the effect of age (continuous variable) on the survivor function. For all statistical calculations, a p value of less than 0.05 was considered significant. The SYSTAT system for statistics was used for all data analysis (V. 6.0 for Windows; SPSS, Chicago, IL).
| Results |
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The mortality rate among patients undergoing endarterectomy was not significantly higher than the mortality rate for patients undergoing CABG without endarterectomy during the same time interval (6% vs 4.5%, p = 0.27). The difference in incidence of myocardial infarction (6% vs 3%, p = 0.069) approached statistical significance, while that of ventricular arrhythmias (22% vs 5.7%, p < 0.001), and reoperation for bleeding (12% vs 4.5%, p < 0.001) were highly significant. Intra-aortic balloon pumps were more commonly inserted preoperatively (22% vs 0.6%, p < 0.001) or intraoperatively (17% vs 2.6%, p < 0.001), but not postoperatively (3% vs 1.6%, p = 0.07), in the study group.
Long-term follow-up information was obtained for all 166 hospital survivors. No differences were seen in actuarial survival curves when compared for patients grouped according to the coronary distribution endarterectomized (data not shown). The actuarial survival curve for the endarterectomy group as a whole is shown in Figure 2. At late follow-up, information regarding recurrent angina pectoris, myocardial infarction known to the patient, repeat catheterization, and reintervention was obtained from 117 survivors of right (mean 60.4 ± 37.9 months) or left-sided (mean 48.8 ± 39.6 months) endarterectomy. As shown in Table 4 , 73% of patients were free of recurrent angina pectoris. Only 5 (4%) knew of an interval myocardial infarction. Among the more objective measures of success, 15% had undergone repeat cardiac catheterization, 6% subsequent angioplasty, and 3% repeat coronary artery bypass surgery. There were no statistically significant differences between endarterectomy groups.
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| Comment |
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These results do not argue for expansion of the use of coronary endarterectomy beyond the specific circumstance for which it was performed in this series. We made no attempt to compare the long-term results with patients undergoing endarterectomy to those obtained in patients undergoing primary coronary bypass grafting, because these populations are inherently dissimilar by virtue of the very nature of their coronary disease. The clinical issue we attempted to address is decision-making in the management of the otherwise ungraftable vessel between endarterectomy prior to grafting, leaving the target ungrafted, or applying new technologies such as TMR or growth factor therapy to the vessel distribution.
Endarterectomy was employed for revascularization an order of magnitude less commonly in our experience than the 20% to 50% frequency reported in many published series [513]. As such, our results may be more representative of common practice [14]. Despite this apparent difference in patient selection, our operative mortality was remarkably similar to the 2% to 6% reported by those performing endarterectomy much more frequently [511]. The incidence of myocardial infarction in the current series compares favorably to the 2% to 12% reported by others [513]. In contrast to the results reported by Livesay and associates [9] and Djalilian and Shumway [8], the risks associated with endarterectomy of the LAD did not exceed those for endarterectomy of the RCA in our series. This finding is consonant with those reported by Brenowitz and associates [6], Christakis and coworkers [7], and Minale and associates [10].
The literature suggests that the late results of coronary endarterectomy are acceptable with 5-year actuarial survival ranging from 71% [8] to 90% [7]. Series differ significantly in the frequency with which the technique is employed as noted above, and may, therefore, differ in subtle ways with respect to co-morbidities and expected survival. In addition, the mode of reconstruction may impact on survival. Beretta and associates [12] have argued in favor of the use of the internal thoracic artery for reconstruction of the LAD with a reduction in perioperative myocardial infarction from 10% to 2%, an improvement in early patency from 85% to 93%, and improvement in 5-year survival from 70% to 87%. Our late results are compatible with these reports.
The rate of recurrent angina of 27% which we observed is well in excess of the 18% recurrent angina rate reported by Sergeant and associates [15] in their analysis of 9,600 patients undergoing primary CABG. It is, however, similar to that reported by other authors after coronary endarterectomy. Gill and associates [13] observed recurrent angina in 15% of their patients at a mean follow-up of 36 ± 16 months, while Djalilian and Shumway [8] reported the same in only 9% of their patients at 46 ± 19 months. Christakis [7], however, reported a disappointing 65% freedom from angina at 5 years. The difference in recurrence of symptoms between patients undergoing endarterectomy and those undergoing primary grafting may be due to the diffuse and particularly severe nature of the coronary disease present among the population requiring endarterectomy. Alternatively this difference may reflect the suboptimal revascularization achievable with this technique. In either case, we agree that primary CABG without endarterectomy is preferable whenever possible.
The study suffers from the weakness inherent in any retrospective study, including potential inconsistency of data captured over time, dependence on patient interview for the acquisition of late events, and the absence of a control group. Accordingly our conclusions emphasize the hard end-point of death, particularly in the perioperative period. The difficulty in identifying an appropriate control group has been discussed previously. Additionally, information regarding graft patency is lacking either by cardiac catheterization or by surrogates such as noninvasive perfusion imaging or wall motion studies. Such analyses were not performed consistently in our study group but have been adequately addressed previously in the literature. Beretta and associates [12] demonstrated an early graft patency of the internal thoracic artery to the endarterectomized LAD of approximately 90% falling to approximately 80% between 30 and 36 months postoperatively in their study of 46 patients. Similarly, Gill and coworkers [13] reported a 74% patency at 36 ± 16 months for LAD endarterectomies reconstructed with the internal thoracic artery. In a study of 68 endarterectomized vessels predominated by RCA interventions, Goldstein and associates [11] observed a similar early patency which fell to 65% at a mean of 19 months. Interestingly, these investigators observed little correlation between symptoms and patency of the endarterectomized vessel.
Analyses of changes in wall motion have produced mixed results. In the study by Gill and associates previously cited [13], wall motion assessed by ventriculography demonstrated a statistically insignificant trend toward improvement. In contrast, Minale and associates [10] studied 635 patients undergoing endarterectomy of any vessel, with roughly equal numbers of patients demonstrating improvement or deterioration in function.
Despite the limitations of this study, the data presented here are sufficient to support endarterectomy as a legitimate option in suitable patients for whom a vascular territory would otherwise not be revascularized. Coronary endarterectomy can be undertaken, even in centers in which it is performed only sparingly, with acceptable perioperative risk. It should therefore be considered as an alternative or supplement to the use of novel technologies such as TMR or growth factor therapy. The results of studies of these new approaches to diffuse coronary artery disease, particularly when used in combination with coronary bypass grafting, should be considered in the context of the results achievable with this more traditional approach.
| Acknowledgments |
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| Footnotes |
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| References |
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