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Ann Thorac Surg 1999;67:989-993
© 1999 The Society of Thoracic Surgeons
a Cardiothoracic Unit, Hammersmith Hospital, Imperial College School of Medicine, London, England, United Kingdom
Accepted for publication September 12, 1998.
Address reprint requests to Mr Ratnatunga, Cardiothoracic Unit, Hammersmith Hospital, Imperial College School of Medicine, Du Cane Rd, London W12 0NN, England
| Abstract |
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Methods. Data from the 56 patients, who underwent coronary endarterectomy in our institution between January 1993 and August 1996, were reviewed retrospectively and compared with a control group of 56 patients matched for age, sex, LV function, and angina class. In the endarterectomy group, there were 47 men and nine women, with a mean age of 59.6 years. The mean follow-up time was 21 months. Indications for operation were angina in 45 (80.3%), angina with signs or symptoms of cardiac failure in 3 (5.4%), and prognosis in 8 (14.3%) asymptomatic patients.
Results. Fifty (89%) patients had one, four (7.2%) had two, and 2 (3.6%) patients had three coronary arteries endarterectomized. Of these 64 endarterectomies, 33 (51.5%) involved the right coronary artery, 20 (31.3%) the left anterior descending artery, and 11 (17.2%) branches of the circumflex artery. There were three (5.4%) nonfatal myocardial infarctions in the endarterectomy group, but none in the control group (p > 0.05). Two patients (3.6%) in the endarterectomy group, but none in the control group, died within the first 30 days (p > 0.05). Actuarial survival and incidence of recurrent angina were similar in the two groups.
Conclusions. In current cardiac surgical practice, coronary endarterectomy displays satisfactory rates of postoperative morbidity and medium term results in selected groups of patients.
| Introduction |
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The aim of the present study is to evaluate the outcome of coronary endarterectomy, in our institution, performed in association with primary CABG in the mid 1990s.
| Patients and methods |
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Data concerning the hospital stay of the endarterectomized patients were extracted from our prospective computerized clinical database. In addition, the clinical notes of these patients were reviewed retrospectively. When the information provided by the clinical notes was not adequate, the patients general practitioner was contacted by telephone or mail.
Table 1 summarizes the preoperative clinical features of the study patients. The mean follow-up time was 21 months (range 248 months), amounting to a total of 100.5 patient years. Indications for operation were angina in 45 (80.3%) patients, angina with signs or symptoms of cardiac failure in 3 (5.4%), and prognosis in 8 (14.3%) asymptomatic patients.
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For comparison, preoperative clinical information concerning the total group of 1366 patients who underwent isolated primary CABG during the study period is also shown in Table 1.
Surgical technique
Cardiopulmonary bypass was sustained for all operations using a hollow fiber membrane oxygenator (Bard William Harvey, Haverhill, MA). In the endarterectomy group, myocardial management was achieved with intermittent ischemia and ventricular fibrillation in 29 (51.8%), antegrade warm (32°C) blood cardioplegia in 14 (25%), antegrade crystalloid cardioplegia (St Thomas) in 8 (14.3%), and antegrade cold (6°C) blood cardioplegia in 5 (8.9%) patients. The frequency of the different myocardial management techniques was comparable in the control group (Table 2 ). Core temperature during cardiopulmonary bypass was maintained at moderate hypothermia between 30° and 32°C. None of the patients received aprotinin or amicar during the operation.
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Peri- or postoperative myocardial infarction was defined by persistent electrocardiographic changes such as new Q waves, loss of R wave progression, new intraventricular conduction defect or by new echocardiographic evidence of wall kinetic abnormality. All patients received a routine evaluation with electrocardiogram immediately postoperatively and on days two and five. In the presence of suspected or proved myocardial infarction, patients received several electrocardiograms and echocardiography. Serial postoperative creatine kinase levels were not routinely obtained.
Statistical analysis
Nominal data were analyzed using
2 test and interval data using t test. Actuarial survival rates were calculated by Kaplan-Meier survival analysis and actuarial survival curves were compared by log-rank test. Statistical significance was determined by p < 0.05.
| Results |
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Early morbidity
The hospital complications observed are presented in Table 3. There were three (5.3%) nonfatal myocardial infarctions in the endarterectomy group, but none in the control group (p > 0.05).
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Early mortality
There were no early deaths in the control group, but two patients (3.6%) died within the first 30 postoperative days in the endarterectomy group (p > 0.05). One of these patients was a 64-year-old woman with poor LV function (EF < 0.3). The insertion of an intra aortic balloon pump was required preoperatively due to low cardiac output. After completion of the operation, she developed ventricular fibrillation that responded to internal cardiac massage and cardioversion. The patient was transferred to the intensive care unit (ICU) on a high dose of inotropic support, but never regained consciousness and died on the 11th postoperative day.
The other early death occurred in a 77-year-old man, also with poor LV function (EF < 0.3), who underwent urgent simultaneous CABG with repair of an abdominal aortic aneurysm. He required abdominal reexploration for bleeding from the proximal anastomosis of the aortic graft, subsequently developed low cardiac output syndrome and renal failure, and died 48 hours postoperatively.
The endarterectomy group displayed similar early mortality (3.6%) to the total CABG population in our hospital (3.2%).
Actuarial survival and follow-up
There was no significant difference in the actuarial survival between the two groups (Fig.1 ). Three of the patients who underwent coronary endarterectomy died after discharge from hospital. One of these patients was a 45-year-old woman from overseas, suffering from renal failure requiring hemodialysis, who died twelve months postoperatively, after she returned to her home country. Sepsis was reported as the cause of death. A 79-year-old woman died of large bowel perforation 14 months after cardiac surgery. The only late death that was due to cardiac reasons occurred in a 65-year-old male patient with known preoperative poor left ventricular function, who died of cardiac failure three months postoperatively.
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In the endarterectomy group, three patients underwent recatheterization postoperatively. A 40-year-old female developed recurrent angina 18 months after revascularization of the obtuse marginal and right coronary arteries with endarterectomy of the right coronary artery. Coronary catheterization revealed complete occlusion of the right coronary artery venous graft. A 50-year-old male was recatheterized, for recurrent angina, one year after CABG. However, all grafts and native coronary arteries were patent. A 46-year-old male underwent recatheterization for recurrent angina, 18 months after CABG with endarterectomy of the right coronary artery. This patent but progressive disease was demonstrated in the left anterior descending artery. There were no reoperations during the study period.
| Comment |
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Preoperative characteristics (Table 1)
The patients who underwent coronary endarterectomy in this study were not different in preoperative terms to the control group or the total CABG group. The higher incidence of preoperative myocardial infarctions among the endarterectomized patients might reflect the fact that coronary artery disease is more diffuse in this group, even though this did not result in poorer LV function.
Early mortality and morbidity
The incidence of early (most commonly 30 day) mortality reported in previous studies has been consistently between 2%8%, throughout the last fifteen years [6, 7, 9, 11, 1319]. These figures were higher than in patients undergoing CABG without coronary endarterectomy in the same institutions but, nevertheless, demonstrate a significant reduction in mortality in comparison to the early years of endarterectomy. Recently, Djalilian and Shumway [7] reported two (3.1%) early deaths in 64 patients who underwent coronary endarterectomy, between 1988 and 1992. Our operative mortality of 3.6% in the endarterectomized group is higher when compared to the control group, but the difference is not statistically significant. This could reflect improved operative outcomes with contemporary management strategies. Early mortality was also reported to be higher after endarterectomy of the LAD artery [9] and in patients undergoing endarterectomy in more than one coronary artery [6]. Although only 31.3% of our patients had LAD artery endarterectomies, and although the number of multiple endarterectomies was low (11%), both our early deaths followed endarterectomy in more than one vessel and both included endarterectomy of the LAD artery. In line with previous experience, our strategy is to avoid endarterectomy of the LAD artery except in those situations where it is essential for technical reasons. Although it was not a significant predictor of mortality in our series, the fact that both our deaths were in LAD artery endarterectomized patients means that we shall continue to attempt to avoid this particular procedure.
Myocardial infarction is the main perioperative complication in patients undergoing coronary endarterectomy with a reported incidence from 1.5%19% [6, 7, 9, 1315, 18], probably depending on the diagnostic criteria. In our study, three (5.6%) of the 56 endarterectomized patients, but none in the control group, suffered a non-fatal perioperative myocardial infarction. These low mortality and morbidity rates and small patient numbers preclude any reliable univariate analysis of the risk factors associated with postoperative early mortality and myocardial infarction. Patients suffering other causes of early morbidity, such as sternal wound infection and stroke, had a prolonged hospital stay, but eventually enjoyed full recovery. Overall, the two groups displayed similar rates of early morbidity, with the exception of pleural effusions requiring drainage, which were more common among endarterectomized patients (p = 0.027). This difference is not related to the duration of CPB (p > 0.05) or any other clinical parameters and is probably due to statistical error Type II, because endarterectomy is unlikely to be the cause of increased intrapleural hemorrhage. The incidence of sternal wound infection requiring treatment remained low and did not reach a statistically significant difference between the two groups.
Actuarial survival
Previous reports displayed actuarial survival rates of 96.7% at one year [15] and 71%92% at five years after coronary endarterectomy [6, 7, 9, 11, 15, 18]. Multiple endarterectomies have been shown to be associated with shorter long-term survival [6]. The 90% 4-year survival rate in this study is in agreement with these earlier findings. Our control group did slightly, but not significantly, better.
Follow-up
The 74.5% postoperative freedom from angina at 21 months mean follow-up time is comparable to previous reports [6, 9, 18], although Sommerhaug and colleagues. [13] showed 99% of their patients remaining in angina class I at a mean time of 20 months, after long coronary arteriotomy, endarterectomy, and reconstruction of the vessel. According to previous reports employing postoperative recatheterization, early (within 12 months following operation) patency rates of endarterectomized coronary arteries vary from 66% to 90% [7, 8, 11, 14]. Late (after 12 months following operation) patency rates are reported between 56% and 75%, depending on the time span between CABG and recatheterization [7, 18, 11, 1416]. Recatheterization following endarterectomy is not routine in our institution and the small number of patients who underwent repeat catheterization after endarterectomy does not allow us to comment on our patency rates. It is encouraging, however, that only three patients had recurrent angina severe enough to justify repeat catheterization, although freedom from angina does not necessarily imply patency of grafts and native vessels.
The anticoagulation protocol after coronary endarterectomy has evolved in our institution from exclusive use of warfarin (to achieve an international normal ratio of 2.5 3.5), to exclusive early (300 mg daily starting within eight hours following operation) use of aspirin, to currently employing both warfarin (INR at 2.0 mg) and early low dose aspirin (75150 mg daily) for a period of three months. The strategy of inhibiting both arms of thrombus formation may produce further improvement in the outcome following endarterectomy and result in lower medium-term mortality in these high-risk patients. After the first three postoperative months, the administration of warfarin is discontinued, whereas aspirin, in doses of 150300 mg daily is given indefinitely.
In summary, the present study demonstrates that coronary endarterectomy remains a procedure performed in a small percentage of patients undergoing primary CABG with the right coronary artery as the most commonly endarterectomized vessel. The procedure has a low rate of postoperative mortality and morbidity, and relief from angina is obtained in the majority of patients. As the long-term outcome of coronary endarterectomy is known to be moderate [6, 9], these satisfactory medium- term results do not support the universal use of coronary endarterectomy, but suggest that there is potential benefit associated with this procedure in an increasing number of patients with advanced complex coronary artery disease.
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