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Ann Thorac Surg 2007;83:496-501
© 2007 The Society of Thoracic Surgeons
Cardiovascular Surgery Clinic, Goztepe Safak Hospital, Istanbul, Turkey
Accepted for publication September 20, 2006.
* Address correspondence to Dr Ogus, Caferaga Mh. Bahariye C. 54/1, Kadikoy, Istanbul, Turkey (Email: togus{at}superonline.com).
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Abstract |
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METHODS: Between April 1997 and February 2006, 3736 coronary artery bypass grafting (CABG) operations were performed by our team. Of these cases, 524 patients (14%) with the diffusely diseased LAD underwent a long-segmental reconstruction procedure with a LITA graft.
RESULTS: The cohort consisted of 372 men (71%) and 152 women (29%), and the mean age was 56.5 ± 8.2 years. The mean length of the arteriotomy incision was 4.5 ± 1.2 cm (range, 2 to 10 cm). Postoperative mortality was 1.9%, and the myocardial infarction rate was 6.9%. At 3, 5, and 7 years, overall survival was 93.8% ± 0.5%, 89.6% ± 1.5%, and 85.5% ± 2.6%, and actuarial freedom from angina recurrence was 94.5% ± 1%, 88.5% ± 2%, and 82.9% ± 3%, respectively. Among survivors, interim angiographic evaluation was performed in 128 patients at a mean follow-up of 52.4 ± 13.5 months, and the patency rate of the LITA–LAD anastomosis was 91.4%.
CONCLUSIONS: Patients with diffuse LAD disease present a major challenge for cardiovascular surgeons. The long-term results of long-segmental LAD reconstruction are very encouraging, and this approach may be used safely in this subgroup of patients.
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Introduction |
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TopAbstractIntroductionMaterial and MethodsResultsCommentReferences |
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Although coronary endarterectomy has been tried as an alternative adjunct [4–10], most surgeons are still reluctant to use this approach because of the controversial results reported in the literature. Thus, cardiac surgeons are now focused on new techniques that avoid an endarterectomy procedure or at least limit the length of the endarterectomized arterial segment.
Recently, different means of LAD reconstruction using long-segmental anastomosis techniques have been introduced in this special subgroup of patients to afford complete myocardial revascularization [11–18]. The early results suggest that these approaches are comparable with conventional bypass techniques, but only a limited number of studies have reported the clinical outcomes, patency rates, and the incidence of cardiac-related events at long-term follow-up. Furthermore, the heterogenous nature of the patient populations in different studies renders more difficult the interpretation of the results and confuses the data analysis. This retrospective study was conducted to review the long-term results obtained with extended LAD reconstruction with the left internal thoracic artery (LITA) combined with conventional CABG to other territories for diffuse coronary artery disease.
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Material and Methods |
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TopAbstractIntroductionMaterial and MethodsResultsCommentReferences |
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The presence of severely limited distal run-off (<1 mm) determined at the preoperative angiogram or intraoperatively usually precludes the use of an extended anastomosis technique, and these patients underwent a coronary endarterectomy procedure. The endarterectomy procedure may lead to intimal disruption and proliferation, which may influence the long-term patency rates. Therefore, the patients who required an endarterectomy were not included in the analysis to overcome any statistical bias. Redo cases and patients who had concomitant cardiac procedures were also excluded from the study protocol. This retrospective study was approved by the Ethics Committee of the institution, and informed consent was obtained from each patient.
Patient Demographics
The preoperative characteristics are listed in Table 1. The mean patient age was 56.5 ± 8.2 years (range, 41 to 82 years), and 372 (71%) were men. Mean preoperative ejection fraction was 0.55 ± 0.104 (range, 0.20 to 0.70), and 92 (17.5%) had an ejection fraction of less than 0.35. The mean preoperative Canadian Cardiovascular Society anginal class (CCSAC) was 2.7 ± 0.5. There were 236 patients (45%) with stable angina and 121 (23%) with unstable angina. Preoperative angiograms revealed single-vessel disease in 84 patients (16%), double-vessel disease in 121 (23%), triple -vessel disease in 246 (47%), and left main coronary artery stenosis in 73 (14%). The proximal LAD was totally occluded in 105 patients (20%). In the study cohort, 245 patients (46.7%) sustained a remote (>1 month) myocardial infarction (MI). All patients had been prescribed at least one antianginal medication, and the mean number was 2.5 ± 0.6 drugs per patient.
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In 385 patients (73.5%), the operations were performed using standard cardiopulmonary bypass (CPB) techniques under moderate hypothermia (28°C). Myocardial protection was achieved with either antegrade or retrograde blood or crystalloid cardioplegia. The bypass procedure was performed with hypothermic fibrillatory arrest in 85 patients (16%), and their aortas were not cross-clamped because of severe calcification of the ascending aorta. Because the technique may be time-consuming, some patients may not tolerate the selective blood flow interruption. If we foresee during the operation that the length of the arteriotomy will exceed 3 cm, we prefer to place the patient on CPB and perform the coronary anastomoses under hypothermic fibrillatory arrest. For the remaining 54 patients (10.5%), an off-pump CABG operation was performed.
A pedicled LITA graft was used to reconstruct the LAD in all patients. A long superficial arteriotomy was made along the diseased LAD, and the length of incision was decided at the operation. The tip of the arteriotomy incision was extended to the disease-free distal portion of the vessel. The LAD was also opened proximally until the healthy part of the vessel was reached. The LAD was not opened at the level of the first proximal lesion. The LITA was then opened longitudinally, adjusting its length to the length of the LAD arteriotomy. Long-segmental LAD reconstruction was performed by covering the arteriotomy with LITA as an onlay graft by using continuous, 7-0 polypropylene suture (Fig 1). In patients who required an extended anastomosis to other myocardial territories, this technique was applied by using saphenous vein as the onlay graft. All proximal anastomoses were done while the aortic cross-clamp on.
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Statistical Analysis
Hospital and follow-up records were retrospectively reviewed to determine the morbidity and mortality rates for each patient. Data for physical examinations, laboratory tests, and electrocardiography were obtained regularly. The clinical assessment also included the angina status of each patient and the antianginal drugs prescribed. Postoperative MI was defined as the occurrence of new Q wave in the electrocardiogram and a creatine kinase-MB fraction elevation 10 times above normal within 24 hours after surgery. Prolonged mechanical ventilation time was defined as the requirement of mechanical ventilatory support for more than 24 hours. Survival and any cardiac events, including angina recurrence, new MI, and reinterventions were assessed. Continuous variables are presented as means ± standard deviations. Categoric variables are presented as percentage. The Kaplan-Meier method was used to analyze survival and freedom from angina recurrence. Values of p < 0.05 were considered significant.
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Results |
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Early Outcomes
Reexploration was required for bleeding in 16 patients (3%). In-hospital new MI was observed in 36 patients (6.9%), which were localized to the LAD territory in 19 patients (3.6%) and to a different territory in 17 (3.2%). The remaining perioperative complications included transient neurologic event in 21 patients (4%), major stroke in 6 (1.1%), mediastinitis in 3 (0.5%), prolonged mechanical ventilatory support in 51 (9.7%), renal failure requiring transient dialysis in 16 (3%), and an increase of serum creatinine level (>2 mg/dL) in 48 (9%).
Ten patients died within the first 30 days for an early mortality rate of 1.9%. Six of these deaths were related to low cardiac output, and all of these patients had a preoperative ejection fraction of less than 0.40. Acute renal failure developed in 2 patients with preoperative renal dysfunction (serum creatinine levels were 2.2 and 2.7 mg/dL, respectively), and they died at the postoperative days 11 and 15. The remaining deaths were due to multiorgan failure and sepsis.
Late Outcomes
Six patients were lost to follow-up; thus, follow-up included 508 (99%) of 514. The mean follow-up was 53.7 ± 22 months (range, 7 to 94 months), and 45 patients (8.8%) died during the follow-up period. Causes of late death were cardiac-related in 17 patients, consisting of congestive heart failure in 9, new MI in 6, and ventricular arrhythmia in 2; the remaining 28 deaths resulted from malignancy in 18 patients, chronic renal failure in 8, and other causes in 2. Overall survival, including all deaths, at 3, 5, and 7 years was 93.8% ± 0.5%, 89.6% ± 1.5%, and 85.5% ± 2.6%, respectively (Fig 2). Among survivors, 392 patients (84.6%) were symptom-free, 45 (9.7%) were in CCSAC I–II, and 26 (5.7%) were in CCSAC III to IV.
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Interim angiographic evaluation at a mean follow-up of 52.4 ± 13.5 months was possible in 128 patients, including 42 symptomatic patients (27.6% of 463 late survivors) from whom informed consent was obtained. Of the long segmental LITA–LAD anastomosis, 91.4% were completely patent (117 patients) (Fig 4). Eight patients (6.3%) had string sign, and 3 (2.3%) had complete occlusion. Among all symptomatic patients, 18 underwent a percutaneous intervention, and 3 required a redo operation at the end of 5 years of follow-up. Actuarial freedom from reintervention in the entire cohort at 3, 5, and 7 years was 96.5% ± 0.8%, 93.3% ± 1.5%, and 88.0% ± 3%, respectively. Only 5 symptomatic patients required a percutaneous intervention for the LITA–LAD anastomosis, but the small number of patients precluded statistical analysis.
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Comment |
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TopAbstractIntroductionMaterial and MethodsResultsCommentReferences |
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Coronary endarterectomy is usually the technique of choice in patients presenting with diffuse and extensive coronary artery disease. Although the benefits endarterectomy of the LAD have been published [5–10], many surgeons are still reluctant to use this technique because of its high perioperative and postoperative mortality rates [19, 20]. Another major concern with this technique is the development of myofibrointimal proliferation, which negatively affects the early and long-term clinical and angiographic results. Denuded endothelium with endarterectomy enhances myofibrocyte proliferation, and the endarterectomized arterial wall acts as a scaffold for the new thrombus formation. Rapid endothelial covering results because the endarterectomized area is reduced, and this may in turn decrease the long-term graft failure. The main goal at surgical intervention in patients with diffuse CAD should therefore be the achievement of complete myocardial revascularization with a limited endarterectomy.
The long-term benefits of the LITA–LAD bypass has been well established and previously reported by many authors [21, 22]. In addition, previous studies that used long-segmental reconstruction of the LAD with the LITA revealed acceptable early and mid-term results [1, 13]; however, the major limitations of these studies are the small number of patients and the short duration of the clinical follow-up. We have presented a study evaluating the long-term clinical and angiographic results of this technique in a large cohort. Since 1997, we have adopted the extended anastomosis technique and used it in all patients with diffuse coronary artery disease. In our series, the aortic cross-clamping and CPB times were comparable with those of conventional CABG operations. More liberal use of retrograde blood or crystalloid cardioplegia decreased significantly our rates of postoperative mortality and MI.
Our mortality rate is slightly lower than other series dealing with diffuse coronary artery disease. Barra and colleagues [1], using a similar reconstruction technique, reported a 3.7% perioperative mortality rate in their series of 108 patients. We believe that this difference may be due to the younger age of our patient cohort. In their series of 83 patients, Santini and colleagues [14] reported a very excellent mortality rate of 1.2% in this challenging patient population. Their mortality rate is slightly lower than what we reported; but the morbidity rate, including MI, is similar to ours. Overall survival and freedom from angina recurrence rates are also similar to previous reports. Fukui and colleagues [13] reported a survival rate of 93.5% at 45 months. The main advantage of our study is that our overall follow-up period is longer than previously reported series.
By using a long-segment anastomosis, we believe that the ostia of septal and diagonal branches can be directly visualized intraoperatively and a secure anastomosis can be reconstructed. In our technique, we opened the diseased vessel, and the arteriotomy was extended to the nondiseased proximal and distal portions of the LAD. Theoretically, the incorporation of healthy, disease-free parts of the LAD into the anastomosis decreases significantly the development of neointimal proliferation.
Our technique differs from that of Barra and colleagues [1], who exclude the atheromatous plaques from the lumen of the LAD. In their technique, the LITA has been settled inside the LAD to exclude the atheromatous plaques from the LAD lumen. At the end of the procedure, 75% of the newly formed LAD originates from the LITA and 25% originates from the native artery floor. The atheromatous plaques are left outside the lumen of the newly reconstructed LAD in this technique. These authors stated that the newly formed vessel has a greater diameter than the native artery.
According to our experience, however, the size and lateral extension of plaque formation are not homogenous along the arterial wall and it is not always possible to achieve the desired vessel diameter throughout the newly formed LAD. We therefore decided to open the diseased vessel until the healthy proximal and distal portions were reached and put the plaques inside the anastomosis to avoid the narrowing of the diameter of the new LAD.
We used both the LAD and LITA vessels to construct the new artery. Because the new vessel generally has a greater diameter than the native artery, the size of the LITA has no major significance. We agree with Barra and colleagues’ [1] statements that the presence of fragile plaques in the lumen may increase the incidence of plaque-related complications. In patients with fragile and ulcerated plaques, we did an endarterectomy procedure instead of long-segmental anastomosis. Indeed, by the exclusion of such cases, we did not observe any adverse plaque-related complications in patients undergoing a long-segmental anastomosis.
In their series of 83 patients, Santini and colleagues [14] reconstructed the LAD with saphenous vein and anastomosed the LITA onto the patch. The described procedure is acceptable, but more time consuming. Another concern with the technique is the degree of compliance of the three different components: the native artery, saphenous vein patch, and the LITA. As mentioned by the authors, the compliance of saphenous vein patch may cause energy loss. In addition, the larger diameter of saphenous vein may adversely influence the flow patterns, and subsequent turbulence may, in turn, decrease the flow velocity.
Vein graft atherosclerosis, which is a significant cause of recurrent angina, is another concern with a saphenous vein patch [23]. Indeed, although it is not possible to compare the two cohorts, the incidence of recurrent angina in our patients is less than reported by Santini and colleagues using saphenous vein as an onlay patch. This difference may originate from our more liberal use of the extended anastomosis technique because our patient group represents 14% of all patients, while this proportion was 1.4% in their series.
A major concern with percutaneous interventions, including both angioplasty and stenting, is the acceleration of the atherosclerotic disease process because of the superimposition of mechanical injury. Furthermore, some studies have stated that C-reactive protein may promote the inflammatory component of atherosclerosis by inducing the expression of intercellular adhesion molecule-1 [24]. Previous stenting of the proximal major lesion may therefore play a role in the development of future multisegmental stenosis throughout the distal LAD after a percutaneous intervention. In our series, 16 patients (3%) had previously undergone a percutaneous intervention for the treatment of the first major stenotic lesion. In-stent restenosis developed in only 3 of these 16 patients, and the remaining patients required a long-segment reconstruction because of the development of distal multisegmental LAD disease. The identification of the exact cause for this disease progression is out of the scope of this report and requires further clinical randomized studies.
The major limitations of our study are its retrospective design and the absence of a control group. Again, interim angiography was performed in only 27% of patients from whom informed consent could be obtained.
The long-term results of long segmental LAD reconstruction are very promising in patients with diffuse LAD disease. In this challenging patient population, our study revealed comparable results with those of patients with non-diffuse coronary artery disease.
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References |
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TopAbstractIntroductionMaterial and MethodsResultsCommentReferences |
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