Ann Thorac Surg 2005;79:1999-2003
© 2005 The Society of Thoracic Surgeons
Original article: Cardiovascular
Coronary Endarterectomy: Impact on Morbidity and Mortality When Combined With Coronary Artery Bypass Surgery
Ravindranath Tiruvoipati, FRCSa,*,
Mahmoud Loubani, MD, FRCSIa,
Mauro Lencioni, MRCPb,
Shilajit Ghosh, FRCS(CTh)a,
Peter W. Jones, PhDc,
Ramesh L. Patel, MD, FRCS(CTh)a
a Department of Cardiothoracic Surgery, University Hospitals of Coventry and Warwickshire NHS Trust, Walsgrave Hospital, Coventry
b Department of Cardiology, University Hospitals of Coventry and Warwickshire NHS Trust, Walsgrave Hospital, Coventry
c Department of Statistics, School of Computing and Mathematics, Keele University, Keele, United Kingdom
Accepted for publication December 28, 2004.
* Address reprint requests to Dr Tiruvoipati, Dept of ECMO, Glenfield Hospital, Groby Rd, Leicester, LE3 9QP, United Kingdom (E-mail: travindranath{at}hotmail.com).
 |
Abstract
|
|---|
BACKGROUND: The results of coronary endarterectomy (CE) performed in addition to coronary artery bypass grafting (CABG) have been controversial. We aimed to examine the impact of CE performed in addition to CABG when compared with CABG alone in our unit.
METHODS: Patients who had CABG between January 1995 and December 2001 were included. They were divided into two groups, the CABG-only group and CABG and CE group. The following outcomes were compared: perioperative myocardial infarction, postoperative ventricular arrhythmias, cerebrovascular accident, renal impairment, and early mortality.
RESULTS: Of 5,782 patients who underwent CABG, 461 patients (8.6%) required CE in addition to CABG. There was a higher mortality and incidence of postoperative renal impairment in the group of patients who had CABG and CE, with no significant difference in other outcomes. However, the patients in the CABG and CE group had a higher incidence of male sex, previous myocardial infarctions, preoperative renal impairment, and poor left ventricular function, with longer cross-clamp and cardiopulmonary bypass times than in the CABG-only patients. Although female sex, renal impairment, nonelective surgery, impaired left ventricular function, and peripheral vascular disease were associated with increased mortality in all the patients, and use of statins and aspirin was associated with a reduction in mortality, CE was not a predictor of mortality. Furthermore, on propensity scores analysis, CE was not associated with increased mortality.
CONCLUSIONS: Coronary endarterectomy when combined with CABG seemed to be associated with a higher mortality than isolated CABG in our study groups, but this is related to comorbidities of these patients rather than the CE.
|
Introduction
|
|---|
Coronary endarterectomy (CE) was introduced as a method of treating coronary artery disease in 1957 [1] and was performed without cardiopulmonary bypass or associated coronary artery bypass grafting (CABG) [2, 3]. The early results were inconsistent, and it was not until CE was combined with CABG that satisfactory results were obtained [4, 5]. Subsequently, CE as an adjunct to CABG was adopted by several institutions with varying results, and although the procedure was shown to produce relief from angina, early studies reflecting the experiences in 1960s and 1970s recorded an increase in postoperative morbidity and mortality [6].
In the last two decades there has been a resurgence of CE, and although there is a recognized increase in surgical risk [7], the early and late results were seen to support the selective use of CE in patients with diffuse distal disease and the fact that it can be accomplished with acceptable operative risk and good long-term results [8]. Coronary endarterectomy has also been shown to safely achieve complete coronary revascularization with acceptable results, even in patients with end-stage coronary artery disease [9].
The main indication for CE remains the presence of diffusely diseased coronary arteries that are not suitable for distal grafting [6]. Although it has been performed on all coronary arteries, there is some evidence suggesting endarterectomy of the left anterior descending coronary artery is associated with particularly high operative risk [7]. Most surgeons, therefore, perform endarterectomy, especially of the left anterior descending coronary artery, in a highly selective manner and only when no other alternatives exist [8]. Advanced age, previous interventions, coexisting diabetes mellitus, and lipid disorders increase the occurrence of diffusely diseased coronary arteries in patients presenting for CABG and therefore the need for CE [8].
The development of alternative therapies like transmyocardial laser revascularization [10] and angiogenic growth factor therapy [11] for nongraftable coronary disease renews the discussion of the risks and benefits of CE, especially with the modernization of cardiopulmonary bypass, improved handling of the ischemic myocardium, and better postoperative intensive care management. The aim of this study is to compare the results of CE performed in addition to CABG with isolated CABG in our unit and to identify factors associated with mortality.
|
Material and Methods
|
|---|
Patient Selection
Data were collected from our local database called the Patient Analysis and Tracking System. All the patients who had CABG between January 1995 and December 2001 were selected for analysis. Any patient who had other procedures in addition to CABG such as valve repair or replacement or left ventricular aneurysm resection was excluded. The patients were divided into two groups for the purpose of this study, the CABG-only group and the CABG and CE group. Peripheral vascular disease was defined by the presence of symptoms of intermittent claudication, absence of peripheral pulses, or history of previous surgery. Preoperative renal impairment was defined as serum creatinine level of greater than 120 mmol/L.
Coronary endarterectomy was performed in patients with diffuse coronary artery disease when distal anastomosis to an adequately sized vessel supplying a visibly viable myocardium was not possible. All patients received aspirin after the surgery commenced on the first postoperative day and continued for life.
Clinical Outcomes
The following outcomes were measured: (1) early mortality, defined as patients who died within 30 days of the procedure; (2) intraoperative or perioperative myocardial infarction, defined by persistent electrocardiographic changes compatible with myocardial infarction, such as new Q waves, loss of R wave progression, or new atrioventricular conduction defects, associated with elevated cardiac enzymes; all patients had an electrocardiogram in the immediate postoperative period and daily for 5 days; (3) postoperative ventricular arrhythmias; (4) postoperative cerebrovascular accident defined as a persistent neurologic deficit in keeping with a cerebral vascular territory infraction; and (5) postoperative renal impairment, defined as an increase of serum creatinine above 200 mmol/L.
Statistical Analysis
Statistical analysis was done using the statistical package NCSS (2001, J.L. Hintze, Kaysville, UT). Chi-square analysis was performed on categorical variables, and Student’s t test was used for comparison of continuous variables; a p value of less than 0.05 was deemed to have statistical significance. To determine whether variables were independently associated with mortality, a multiple logistic regression analysis was performed. Propensity scores were calculated by using logistic regression with the indicator of procedure as the dependent variable and the variables, which are associated with mortality (from Table 4), as predictors. These scores were then used to split the individuals into quintiles as suggested by Rosenbaum and Rubin [12]. Cross-tabulations of mortality against procedure within quintiles were tested for homogeneity, and a combined estimate of the odds ratio measuring risk of mortality between procedures was calculated. Logistic regression was carried out using NCSS and the homogeneity test, and combination of odds ratios were carried out using StatXact 4 (1999, Cytel Corp, Cambridge, MA).
View this table:
[in this window]
[in a new window]
|
Table 4. Individually Analyzed Risk Factors Associated With Early Mortality in Patients Undergoing Coronary Artery Bypass Grafting and Coronary Endarterectomy
|
|
|
Results
|
|---|
Between January 1995 and December 2001, 5,782 patients underwent CABG in our unit. Of these patients, 461 patients (8.6%) required CE in addition to CABG. The preoperative demographic and clinical characteristics of the two groups of patients are shown in Table 1. Coronary endarterectomy of the right coronary artery was performed in 302 patients (65.5%) and left anterior descending coronary artery in 111 patients (24.1%). The remaining 48 patients (10.4%) had CE at other sites, including the circumflex system and branches of the left anterior descending coronary artery and right coronary artery. The saphenous vein was the most common conduit used after endarterectomy in 377 (81.7%) patients, and the left internal mammary artery was used in 65 (14%) patients.
View this table:
[in this window]
[in a new window]
|
Table 1. Preoperative Demographic and Clinical Characteristics of Patients Undergoing Coronary Artery Bypass Grafting With and Without Coronary Endarterectomy
|
|
The measured outcomes of the patients in the two groups after surgery are shown in Table 2. This demonstrated that CE combined with CABG resulted in a significantly higher mortality than isolated CABG as well as an increase in the incidence of postoperative renal impairment. However, the two groups of patients differed in a number of preoperative clinical characteristics as seen in Table 1, including sex distribution, history of myocardial infarction, renal impairment, and left ventricular (LV) dysfunction, and also had longer cross-clamp and cardiopulmonary bypass times.
Multiple logistic regression analysis of risk factors demonstrated that female sex, renal impairment, nonelective surgery, impaired LV function (ejection fraction < 0.60), and peripheral vascular disease are associated with increased mortality in all patients (CABG-only as well as CABG and CE patients) included in the study (Table 3) and that the use of aspirin and statins was associated with a reduction in mortality. It is interesting to note that in this analysis CE was not associated with an increase in mortality. In the CE and CABG group, age greater than 70, female sex, nonelective procedures, preoperative renal impairment, diabetes mellitus, presence of peripheral vascular disease, and impaired LV function were all noted to be significantly associated with early mortality (Table 4).
View this table:
[in this window]
[in a new window]
|
Table 3. Multiple Logistic Regression Analysis of Preoperative Risk Factors Associated With Postoperative Mortality of All (Isolated Coronary Artery Bypass Grafting and Coronary Artery Bypass Grafting With Coronary Endarterectomy) Patients
|
|
Cross-tabulations of mortality against procedure within quintiles were tested for homogeneity with a resultant p value of 0.11, and hence the odds ratios from each quintile are not significantly heterogeneous. Therefore, they may be combined, and this resulted in an odds ratio of CABG and CE versus CABG alone of 1.40 (95% confidence interval, 0.93 to 2.11; p = 0.11). In other words there was not a significant increase in mortality comparing CE with CABG against CABG alone.
|
Comment
|
|---|
This study represents one of the largest published series of patients undergoing CABG and CE. It demonstrated no significant increase in the incidence of the ventricular arrhythmias, stroke, or myocardial infarction in patients requiring CE, although there was an increase in postoperative renal impairment. However, there was a significant increase in mortality in the CABG and CE group, but this was related to the fact that the patients in this group had higher incidence of comorbidities. Furthermore, CE was not identified as a risk factor for mortality. These findings warrant further discussion.
The reported frequency of performing CE in association with CABG in the literature varies between 3.7% [13] and 42% [14]. This variation is probably because of lack of uniformity in indications for performing CE and variable results [13]. This controversy has persisted since the introduction of CE by Bailey and colleagues [1] for diffuse coronary artery disease. It was largely abandoned initially because of fears of side branch obstruction by the so-called snowplow phenomenon [14]. However, the recent results of coronary endarterectomy are encouraging and are probably the result of better preoperative selection of patients, refinements of the operative techniques, advances in the management of cardiopulmonary bypass, better myocardial preservation methods, and improved postoperative management. In spite of these advances, the mortality and morbidity after CABG and CE is greater than with CABG alone, with some studies showing a statistically significant increase [7, 15–17] and others with an increasing trend in mortality and morbidity [6, 9]. The results of the current study are consistent with these findings [7, 15–17] in the sense that the CABG and CE patients had a higher mortality, but this was not a result of the CE. Furthermore, although some studies have shown an increase in mortality when the left anterior descending coronary artery was endarterectomized [7, 13], in our study this was not associated with increased mortality (data not shown).
The incidence of postoperative myocardial infarction reported in the literature ranges from 5% to 25% [18–21] but was only 1.5% in our patients undergoing CABG and CE. One of the possible explanations for the increased mortality in our study with no significant increase in the incidence of postoperative myocardial infarctions or arrhythmias might be the occurrence of subclinical myocardial infarctions as reported by Minale and associates [17]. This is thought to be caused by antegrade perfusion after CE. Minale and coworkers [17] showed that the results are better when collateral circulation is enhanced by performing isolated CABG to the vessels supplying the adjacent myocardium and avoiding endarterectomy on the blocked arteries supplying the myocardium that is seen to be contracting well. Djalilian and Shumway [22] reported an increased incidence of mortality in patients who had preoperative myocardial infarction. In our study, although there was a higher incidence of preoperative myocardial infarctions in patients who required CE (61.6% versus 52.9%; p = 0.0001), in the analysis for the predictors of mortality this was not found to be independently associated with mortality.
In our study the use of preoperative statins was significantly lower in patients who required CE. In addition to the lowering of lipids, statins have been shown to have favorable effects on endothelial function [23], plaque stabilization, and inflammation [24, 25]. Statins may have a role in reducing the incidence of diffuse coronary disease requiring endarterectomy, although this has not been confirmed in any study so far. Dotani and colleagues [26] reported that preoperative therapy with statins reduced mortality after CABG. This is supported by the findings from our study, which show that statin use was associated with a reduction in mortality in patients requiring isolated CABG as well as in patients requiring CE in addition to CABG.
Atik and associates [13] found female sex, diabetes mellitus, left main disease, myocardial infarction, and an ejection fraction less than 0.35 to be associated with early mortality. Brenowitz and colleagues [15] have reported age older than 70 years, reoperation, insulin-dependent diabetes mellitus, female sex, and severe LV dysfunction as risk factors for patients requiring multiple endarterectomies [15]. The mortality in the CE group in this study was associated with increasing age, particularly older than 70 years, preoperative renal impairment, operations performed as nonelective procedure, diabetes mellitus, presence of peripheral vascular disease, and impaired LV function. Additionally, age greater than 70 years, nonelective operations, peripheral vascular disease, and impaired LV function are independent risk factors for mortality in this group of patients.
In conclusion, the present results of performing CE are increasingly better, and in this series CE was not found to significantly increase morbidity or mortality. Age older than 70 years, female sex, nonelective procedures, preoperative renal impairment, diabetes mellitus, peripheral vascular disease, and impaired LV function are independent risk factors associated with mortality in patients requiring CE. These factors should be considered when performing CE.
|
References
|
|---|
- Bailey CP, May A, Lemmon WM. Survival after coronary endarterectomy in man JAMA 1957;164:641-646.
- Effler DB, Groves LK, Sones Jr FM, Shirey EK. Endarterectomy in the treatment of coronary artery disease J Thorac Cardiovasc Surg 1964;47:98-108.
- Longmire Jr WP, Cannon JA, Kattus AA. Direct-vision coronary endarterectomy for angina pectoris N Engl J Med 1958;259:993-999.
- Groves LK, Loop FD, Silver GM. Endarterectomy as a supplement to coronary artery-saphenous vein bypass surgery J Thorac Cardiovasc Surg 1972;64:514-522.[Medline]
- Klie JH, Johnson L, Smulyan H, et al. Gas endarterectomy of right coronary artery; the importance of proximal bypass graft Circulation 1974;49:63-67.[Abstract/Free Full Text]
- Asimakopoulos G, Taylor KM, Ratnatunga CP. Outcome of coronary endarterectomya case-control study. Ann Thorac Surg 1999;67:989-993.[Abstract/Free Full Text]
- Livesay JJ, Cooley DA, Hallman GL, et al. Early and late results of coronary endarterectomy. Analysis of 3,369 patients J Thorac Cardiovasc Surg 1986;92:649-660.[Abstract]
- Sundt III TM, Camillo CJ, Mendeloff EN, Barner HB, Gay Jr WA. Reappraisal of coronary endarterectomy for the treatment of diffuse coronary artery disease Ann Thorac Surg 1999;68:1272-1277.[Abstract/Free Full Text]
- Marinelli G, Chiappini B, Di Eusanio M, et al. Bypass grafting with coronary endarterectomyimmediate and long-term results. J Thorac Cardiovasc Surg 2002;124:553-560.[Abstract/Free Full Text]
- Frazier OH, Cooley DA, Kadipasaoglu KA, et al. Myocardial revascularization with laser. Preliminary findings Circulation 1995;92(Suppl):II-58-II-65.
- Sellke FW, Laham RJ, Edelman ER, Pearlman JD, Simons M. Therapeutic angiogenesis with basic fibroblast growth factortechnique and early results. Ann Thorac Surg 1998;65:1540-1544.[Abstract/Free Full Text]
- Rosenbaum PR, Rubin DB. Reducing bias in observational studies using subclassification on the propensity score J Am Stat Assoc 1984;79:516-523.
- Atik FA, Dallan LA, de Oliveira SA, et al. Myocardial revascularization with coronary endarterectomy. Stratification of risk factors for early mortality Arq Bras Cardiol 2000;75:269-280.[Medline]
- Qureshi SA, Halim MA, Pillai R, Smith P, Yacoub MH. Endarterectomy of the left coronary system. Analysis of a 10 year experience J Thorac Cardiovasc Surg 1985;89:852-859.[Abstract]
- Brenowitz JB, Kayser KL, Johnson WD. Results of coronary artery endarterectomy and reconstruction J Thorac Cardiovasc Surg 1988;95:1-10.[Abstract]
- Goldstein J, Cooper E, Saltups A, Boxall J. Angiographic assessment of graft patency after coronary endarterectomy J Thorac Cardiovasc Surg 1991;102:539-544.[Abstract]
- Minale C, Nikol S, Zander M, Uebis R, Effert S, Messmer BJ. Controversial aspects of coronary endarterectomy Ann Thorac Surg 1989;48:235-241.[Abstract]
- Bell MR, Gersh BJ, Schaff HV, et al. Effect of completeness of revascularization on long-term outcome of patients with three-vessel disease undergoing coronary artery bypass surgery. A report from the Coronary Artery Surgery Study (CASS) Registry Circulation 1992;86:446-457.[Abstract/Free Full Text]
- Cukingnan RA, Carey JS, Wittig JH, Brown BG. Influence of complete coronary revascularization on relief of angina J Thorac Cardiovasc Surg 1980;79:188-193.[Medline]
- Jones EL, Craver JM, Guyton RA, Bone DK, Hatcher Jr CR, Riechwald N. Importance of complete revascularization in performance of the coronary bypass operation Am J Cardiol 1983;51:7-12.[Medline]
- Jones EL, Weintraub WS. The importance of completeness of revascularization during long-term follow-up after coronary artery operations J Thorac Cardiovasc Surg 1996;112:227-237.[Abstract/Free Full Text]
- Djalilian AR, Shumway SJ. Adjunctive coronary endarterectomyimproved safety in modern cardiac surgery. Ann Thorac Surg 1995;60:1749-1754.[Abstract/Free Full Text]
- Dupuis J, Tardif JC, Cernacek P, Theroux P. Cholesterol reduction rapidly improves endothelial function after acute coronary syndromes. The RECIFE (reduction of cholesterol in ischemia and function of the endothelium) trial Circulation 1999;99:3227-3233.[Abstract/Free Full Text]
- Jialal I, Stein D, Balis D, Grundy SM, Adams-Huet B, Devaraj S. Effect of hydroxymethyl glutaryl coenzyme a reductase inhibitor therapy on high sensitive C-reactive protein levels Circulation 2001;103:1933-1935.[Abstract/Free Full Text]
- Strandberg TE, Vanhanen H, Tikkanen MJ. Effect of statins on C-reactive protein in patients with coronary artery disease Lancet 1999;353:118-119.[Medline]
- Dotani MI, Elnicki DM, Jain AC, Gibson CM. Effect of preoperative statin therapy and cardiac outcomes after coronary artery bypass grafting Am J Cardiol 2000;86:1128-1130.[Medline]
This article has been cited by other articles:
|
|
|
|
 
A. R Abid, A. Farogh, M. S Naqshband, R. P Akhtar, and J. S Khan
Hospital Outcome of Coronary Artery Bypass Grafting and Coronary Endarterectomy
Asian Cardiovasc Thorac Ann,
January 1, 2009;
17(1):
59 - 63.
[Abstract]
[Full Text]
[PDF]
|
|
|
Top
Abstract
Introduction
