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a Thoraxcenter, Department of Cardiothoracic Surgery, University Medical Center Groningen, University of Groningen, the Netherlands
b Thoraxcenter, Department of Epidemiology, University Medical Center Groningen, University of Groningen, the Netherlands
c Thoraxcenter, Department of Cardiology, University Medical Center Groningen, University of Groningen, the Netherlands
d Thoraxcenter, Department of Hematology, Division of Hemostasis, Thrombosis and Rheology, University Medical Center Groningen, University of Groningen, the Netherlands
Accepted for publication September 25, 2007.
* Address correspondence to Dr Boonstra, Thoraxcenter, University Medical Center Groningen, University of Groningen, Hanzeplein 1, PO Box 30,001, Groningen, 9700 RB, the Netherlands (Email: p.w.boonstra{at}thorax.umcg.nl).
| Abstract |
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Methods: We studied 344 patients who underwent complete arterial revascularization using the internal thoracic arteries and the right gastroepiploic artery. Freedom from major adverse cardiac events (MACE) was evaluated by the Kaplan-Meier method, and homogeneity of outcome in strata of patients was assessed using Cox proportional hazards modeling.
Results: Median follow-up of survivors was 9.3 years (range, 0.01 to 12.8 years). The 12-year freedom from MACE was 75.5%. For the composite of MACE, this was 86.9% for cardiovascular death, 93.3% for myocardial infarction, and 89.4% for reintervention. In patients aged older than 65 years, MACE occurred significantly more frequent, with a freedom from MACE of 65.8% compared with 82.6% in younger patients (hazard ratio, 3.4; 95% confidence interval, 2.1 to 5.6, p < 0.001).
Conclusions: Complete arterial revascularization using both pedicled internal thoracic arteries and the gastroepiploic artery in patients with three-vessel disease resulted in an excellent long-term clinical outcome, especially in patients aged younger than 65 years.
| Introduction |
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There are two possibilities for additional arterial grafting material. First, the radial artery provides enough material, it can be used safely, and its reported short- and mid-term clinical results are satisfactory [7]. Second, we and others demonstrated that the right gastroepiploic artery also can be used for complete arterial revascularization in three-vessel disease [8]. Our mid-term follow-up results of CABG using both internal mammary arteries combined with the right gastroepiploic artery appeared to be promising [9, 10]; however, the follow-up was too short to draw definite conclusions. In the present study, we therefore evaluated the long-term clinical outcome of patients with three-vessel disease who underwent CABG with both internal thoracic arteries and the right gastroepiploic artery.
| Patients and Methods |
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For this retrospective study approval from the local Ethics Committee was obtained. Individual patient data were collected without patient identification information. Owing to the retrospective nature of the study, the need for written informed consent was waived.
Surgical Techniques
The surgical techniques are extensively described elsewhere [9, 10]. In brief, all patients were operated on with the use of extracorporeal circulation, using mild hypothermia (28° to 32°C nasopharyngeal temperature) and crystalloid-induced cardioplegic arrest. The right internal thoracic artery (ITA) was routed through the transverse sinus in 75% of the patients to reach the circumflex coronary artery; in 25%, it was routed directly to the left anterior descending coronary artery. The left ITA was routed under the mediastinal fat deep along the parietal left pleura to the left anterior descending coronary artery in 75% of patients and to the circumflex area in 25%. The right gastroepiploic artery was always routed anterior to the liver and through a hole in the diaphragm.
All patients received anticoagulant or antiplatelet drug therapy (mostly aspirin) for at least 1 year after CABG. In most patients, this was continued afterwards to maintain graft patency.
Clinical End Points
Major adverse cardiac events (MACE) were defined as cardiac mortality, myocardial infarction, and coronary revascularization. Cardiac mortality was defined as death due to acute myocardial infarction, acute cardiac arrest, sudden death, or progressive congestive heart failure. Unknown causes of death were classified as cardiac death. For myocardial infarction, pathologic Q-waves had to be present on the electrocardiogram (ECG) in combination with creatine phosphokinase (CPK) and CPK-MB serum levels that exceeded the upper limits of normal ranges. Revascularization was defined as percutaneous coronary intervention (PCI) or redo-CABG during follow-up.
Statistical Analysis
The objective of this study was to evaluate long-term clinical outcome in patients who underwent complete arterial revascularization using three arterial grafts. The primary composite end point was MACE. Event-free survival was graphically depicted using the Kaplan-Meier method. To evaluate the homogeneity of outcome in different categories of patients, Cox proportional hazards regression analysis was performed. Predefined risk factors for MACE included in univariate analyses were baseline data for age, sex, body mass index, left ventricle ejection fraction (LVEF) of 0.30 or less, hypertension, diabetes mellitus, smoking, hypercholesterolemia, history of myocardial infarction, PCI, and concomitant cardiovascular medication. Other factors included the number of distal anastomoses, perfusion duration, and year of surgery.
All tests performed to test the (null) hypothesis of no difference were two-sided. A value of p < 0.05 was considered statistically significant. For all analyses, SAS 9.1 software (SAS Institute, Cary, NC) was used.
| Results |
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30 days) was 1.5%. During follow-up, 3 patients had abdominal surgery: twice for aneurysm of the abdominal aorta and once for a tumor of the stomach. These operations were completed without damage to the gastroepiploic artery.
Clinical Outcome
Median follow-up was 9.3 years (range, 0.01 to 12.8 years). During follow-up, MACE events occurred in 69 patients (20.1%). MACE-free survival is presented in Figure 1, indicating a 12-year freedom from MACE of 75.5%. The 12-year event-free survival for the components of MACE was 86.9% for cardiovascular death, 93.3% for myocardial infarction, and 89.4% for revascularization (also see Fig 1).
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Predictors of Major Adverse Cardiac Events
Cox proportional hazards regression analysis showed differences in the risk for MACE between various strata of known risk factors. Especially in elderly patients (
65 years), the 12-year freedom from MACE was 65.8% compared with 82.6% for younger patients, resulting in a 3.4-fold (95% confidence interval [CI] 2.1 to 5.6, p < 0.001) higher risk (see Fig 2) in the elderly patients. In patients with a moderate to poor left ventricular function before operation, the risk was 1.9-fold higher (95% CI, 1.1 to 3.1; p = 0.02) compared with patients with a normal left ventricular function. A history of hypertension, myocardial infarction before CABG, the number of distal anastomoses, and diabetes mellitus was also associated with the occurrence of MACE. Multivariable analysis showed that myocardial infarction before CABG, the number of distal anastomoses, and diabetes mellitus were no longer independently associated with MACE, whereas age, a history of hypertension, and left ventricular function remained as important predictors for MACE (Fig 3).
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| Comment |
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The beneficial effects of arterial grafts were reported in 1986 [2, 3]. In a 15-year follow-up study of 748 CABG patients, the use of at least one ITA was associated with decreased death, risk of myocardial infarction, reoperations, and less recurrence of angina pectoris [3]. These findings were supported by those from a larger series of 5931 patients in whom the use of only vein grafts revealed a 1.6-fold increased death compared with the use of one ITA combined with vein grafts [2]. Using both left and right ITA resulted in an even better clinical outcome [5, 6]. A large retrospective study of 8123 patients who underwent CABG using both ITAs showed a small but significant reduction in the death rate compared with the use of one ITA [6]. In a 13-year follow-up study comparing bilateral with single ITA grafting, Berreklouw and colleagues [5] demonstrated a reduction of the combined end point of cardiac death, myocardial infarction, reintervention, or recurrent angina.
Despite these data, one arterial graft and a vein graft are still used in most patients. This can be explained by a lack of arterial graft material, especially in patients with three-vessel coronary artery disease. Another explanation might be that there is no evidence of superiority for three pedicled arterial grafts.
In combination with both left and right ITAs, there are several options to obtain additional arterial grafts. First, the radial artery is being used in an increasing number of CABG patients. Several authors reported beneficial angiographic and clinical short-term effects when this artery was used. Possati and colleagues [11] demonstrated a patency rate of 92% after a mean follow-up of 9 years compared with 98% for ITAs [11]; however, long-term angiographic graft patency varied widely.
Like other arterial grafts, the radial artery is very vulnerable to surgical trauma, hypotension, and early graft malfunction whenever
-adrenergic drugs are used. Recent improvements in surgical harvesting technique of the radial artery and in perioperative drug therapy have reduced these problems and consequently have increased the use of the radial artery [12–14].
Another option is the gastroepiploic artery. In contrast with the radial artery, this is a pedicled graft. Beneficial short-term effects, minimal operative risks, and good patency rates have been reported using the gastroepiploic artery [10, 15], and mid-term clinical outcome has also been promising [7, 16]. We previously reported the results of 7 years of follow-up in 256 patients with three-vessel disease who were grafted with the gastroepiploic artery together with both ITAs [7]. After 7 years, 85% were free from angina pectoris, a considerably better result than that reported from studies in patients in whom vein grafts, single ITA grafts, or double ITA grafts were used (59% to 77%) [7].
Other options for additional arterial grafts are the inferior epigastric artery [17] and, rarely used, bovine grafts [18]. However, their short-term patency rates do not warrant their use in routine CABG surgery [17, 18].
The benefit of complete arterial revascularization was less pronounced in elderly patients (
65 years, see Fig 2). Moreover, the gastroepiploic artery should be considered in case of a calcified ascending aorta to avoid side clamping of the aorta for performing the proximal anastomosis. Previous studies suggested that the use of arterial grafts should be particularly preferred in patients with diabetes mellitus [12, 19]. We can neither confirm nor reject this hypothesis. Although hazard ratios indicated a higher risk in our patients with diabetes mellitus, their small number led to wide confidence limits.
Data published on results of patients with coronary revascularization are difficult to compare owing to the wide differences in used types of grafts and inclusion and exclusion criteria. We did, nevertheless, compare our results with those obtained from recently published studies (Table 2) [1, 3, 20–23] and concluded that actuarial survival and actuarial probability of remaining free from myocardial infarction or reintervention, or both, 10 years after the primary operation is excellent.
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