Ann Thorac Surg 2005;80:144-148
© 2005 The Society of Thoracic Surgeons
Original article: Cardiovascular
Off-Pump Coronary Artery Bypass Grafting Using Only Arterial Grafts in Elderly Patients
Kaoru Matsuura, MD,
Junjiro Kobayashi, MD*,
Osamu Tagusari, MD,
Ko Bando, MD,
Kazuo Niwaya, MD,
Hiroyuki Nakajima, MD,
Toshikatsu Yagihara, MD,
Soichiro Kitamura, MD
Department of Cardiovascular Surgery, National Cardiovascular Center, Osaka, Japan
Accepted for publication January 17, 2005.
* Address reprint requests to Dr Kobayashi, Department of Cardiovascular Surgery, National Cardiovascular Center, 5-7-1 Fujishirodai, Suita, Osaka, Japan 565-8565 (Email: jkobayas{at}hsp.ncvc.go.jp).
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Abstract
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BACKGROUND: This study aimed to elucidate the safety and feasibility of off-pump coronary artery bypass grafting with only arterial grafts for elderly patients.
METHODS: Of 653 patients who underwent off-pump coronary artery bypass grafting from April 2000 to December 2003, 581 patients did so with only arterial grafts. The average age was 66.9 ± 9.3 years. The patients were divided into the elder group E (75 years old or more: 111 cases) or the younger group Y (younger than 75 years old: 470 cases). The mean follow-up term was 21 ± 12 months.
RESULTS: Additive and logistic EuroSCOREs of group E were significantly higher than those of group Y (p < 0.0001). The number of bypass grafts was 3.3 ± 0.9 in group E and 3.3 ± 1.1 in group Y (p = 0.43). The proportion of total revascularization was 74% (82 of 111) in group E and 80% (377 of 470) in group Y (p = 0.15). The number of bilateral implementations of internal thoracic artery was 10 (9.0%) in group E and 196 (42%) in group Y (p < 0.0001). The graft patency rate was 98.7% in group E and 97.8% in group Y (p = 0.96). Hospital mortality was 2.7% (3 of 111) in group E and 0.2% (1 of 470) in group Y (p = 0.095). The causes of death were unrelated to cardiac events. Major adverse cardiac events occurred in 5 patients (5.1%) in group E and in 24 patients (5.6%) in group Y (p > 0.99).
CONCLUSIONS: Off-pump coronary artery bypass grafting using only arterial grafts in elderly patients is as safe and feasible as in young patients.
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Introduction
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Off-pump coronary artery bypass grafting (OPCAB) has been widely adopted in response to the suspected hazards of cardiopulmonary bypass and, possibly, because it offers an attractive alternative to percutaneous catheter intervention in coronary artery disease. Recently, OPCAB has become a standard surgical option for coronary artery disease owing to the development of such equipment as the stabilizer and associated techniques. Furthermore, the less invasive nature and the provision of satisfactory outcome of OPCAB have expanded the operative indications to high-risk cases such as elderly patients [1–11]. On the other hand, the selection of graft material, with or without cardiopulmonary bypass, has been a controversial topic for many years. Although it is common knowledge that the internal thoracic artery (ITA) yields the most reliable graft, not a few papers have suggested that other arterial grafts are advantageous, with respect to venous grafts, in terms of long-term graft patency [12–19]. Therefore, we have adopted OPCAB using only arterial grafts (ie, "total arterial OPCAB") in elderly patients, with positive results so far. The objective of this study is to elucidate the safety and feasibility of total arterial OPCAB in elderly patients.
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Material and Methods
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Between April 2000 and December 2003, 653 consecutive patients underwent isolated OPCAB (98% of all isolated coronary artery bypass grafting cases in this period). Of these, total arterial OPCAB was performed in 581 patients. The mean age was 66.9 ± 9.3 years, and 80.2% (n = 466) were male. The mean follow-up term was 21 ± 12 months. The patients were divided into the elderly group (group E; n = 111), in which age was 75 years or more, and the young group (group Y; n = 470), in which age was less than 75 years, at the time of operation. These different age groups did not differ in operative indications. Operative indication was determined by the angiographic findings whether the patients were symptomatic or not. Advanced age was not a contraindication to the operation, and no patients were excluded from the operation because of comorbid diseases. The number of patients who had stents placed during the same period was 2,545. Details of our basic strategy and surgical procedure of OPCAB were reported previously [20, 21]. All patients underwent OPCAB except those patients who required conversion to cardiopulmonary bypass because of hemodynamic instability. Arterial grafts were used in all patients except when arterial grafts were not available. We prefer multiple and complete coronary revascularization with composite or sequential grafting using all available arterial grafts, especially in situ arterial grafts. Aortic no-touch technique is part of the basic philosophy. The flow volume and pattern were measured after the accomplishment of the anastomosis intraoperatively. To prevent arterial spasm, continuous intravenous infusion of diltiazem (0.5 to 1.0 µg/kg) or nicardipine (0.1 to 0.2 µg) was used intraoperatively and during the first 16 hours after the operation. Diltiazem (100 to 200 mg/day) or amlodipine (2.5 to 5.0 mg/day) was then prescribed for oral administration in conjunction with aspirin (162 mg/day), beginning the next morning. Coronary and graft angiography was performed at 10 to 21 days (mean, 14 days) after OPCAB. Graft patency was independently assessed by the interventional cardiologists.
The European System for Cardiac Operative Risk Evaluation (EuroSCORE) was applied as a risk stratification model to score the risk value of our patient groups for mortality [22, 23]. Institutional approval of the study was obtained, and each patients within the study gave informed consent for serving as a subject.
All data were reviewed retrospectively. All continuous values are expressed as mean ± standard deviation. A comparative analysis was performed between the different patient groups. Differences were analyzed with univariate analysis (
2 test, two-tailed Student’s t test, and Mann-Whitney U test, as appropriate). A value of p less than 0.05 was used to indicate significance.
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Results
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The proportion of 75 years or more was not different between the patients who underwent OPCAB and catheter intervention. Preoperative variables are shown in Table 1. The proportion of female patients was significantly greater in group E (n = 39; 35.1%) than in group Y (n = 76; 16.2%; p < 0.0001). Preoperative hemoglobin level was less in group E (12.2 ± 1.5 g/dL) than in group Y (13.4 ± 1.7 g/dL; p < 0.0001). The body mass index was smaller in group E (23.0 ± 3.1 kg/m2) than in group Y (23.9 ± 3.1 kg/m2; p < 0.013). Preoperative cardiothoracic ratio was greater in group E (53.2% ± 5.6%) than in group Y (49.8% ± 5.4%).
Preoperative combined diseases are displayed in Table 2. The percentage with percutaneous catheter intervention history was not different between the two groups. Chronic obstructive pulmonary disease was present in 7.2% (n = 8) of group E and in 1.7% (n = 8) of group Y (p = 0.005). The proportion with acute myocardial infarction as a preoperative condition was significantly greater in group E (9.9%; n = 11) than in group Y (3.8%; n = 18; p = 0.014).
The perioperative variables are shown in Table 3. The operation time was shorter in group E (279 ± 71 minutes) than in group Y (320 ± 84 minutes; p = 0.0002). The number of anastomoses was 3.3 ± 0.9 in group E and 3.3 ± 1.0 in group Y (p = 0.43). The percentage with use of bilateral ITA was significantly less in group E (9.0%; 10 patients) than in group Y (41.7%; 196 patients; p < 0.0001). The complete revascularization rate was 73.9% (82 of 111 patients) in group E and 80.2% (377 of 470 patients) in group Y (p = 0.15). Blood transfusion was required by more patients in group E (46.9%; 46 patients) than in group Y (24%; 103 patients; p < 0.0001).
The EuroSCORE is displayed in Table 4. The additive EuroSCORE of group E was significantly greater than that of group Y. Age is recognized as one of the important risk factors in the EuroSCORE. Therefore, the EuroSCORE excluding the age-related score, which was calculated by subtracting the contribution of age from EuroSCORE, is shown simultaneously. The score of group E remained significantly higher than that of group Y (p < 0.0001). Logistic EuroSCORE, which shows the predictive mortality rate, is also shown in Table 4.
Overall hospital mortality was 0.68% (n = 4). Hospital death was 2.7% (n = 3) in group E and 0.2% (n = 1) in group Y (p = 0.095). None of the hospital deaths were related to cardiac disease; the causes were bowel ischemia, mediastinitis, cerebral hemorrhage, and interstitial pneumonia. As compared with logistic EuroSCORE, overall actuarial hospital mortality was significantly lower than predictive mortality rate. The operative outcome is shown in Table 5. The incidence of major adverse cardiac events, perioperative myocardial infarction, perioperative stroke, and wound dehiscence was not different in the two groups (p > 0.99). Atrial fibrillation occurred more often in group E (20.4%; n = 20) than in group Y (11.9%; n = 51; p = 0.03).
Postoperative angiography was performed in 525 patients (90.4%). The definition of patency was based on the grading by FitzGibbon and colleagues [24]. The early graft patency rate was 97.8% in group Y and 98.7% in group E. There was no significant difference between group E and group Y (p > 0.99).
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Comment
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The number of elderly patients is growing exponentially, and cardiovascular disease, such as coronary artery disease, is strongly associated with death in this population. Many studies have examined the feasibility and efficacy of surgical intervention for cardiac disease in this population, and several reports have indicated that coronary artery revascularization can be performed with an acceptable mortality in octogenarians [25–27]. Now, efforts are aimed at decreasing morbidity and mortality after coronary artery bypass grafting in this population. Peterson and associates [28] reported the largest study of the outcome of coronary artery bypass grafting in octogenarians. This revealed longer hospital stays, larger hospital costs, and worse short-term mortality in comparison with the younger population. However, the long-term mortality of the patients in this population was similar to that of the general octogenarian population.
Recently, OPCAB has undergone widespread acceptance because of its cost-effectiveness and the commercial availability of stabilizing devices, not to mention the development of the operative techniques. And, worthy of special mention is that the indication for OPCAB has been expanded to include elderly patients and higher-risk patients, because of its reduced invasiveness. Ricci and associates [29] retrospectively reviewed the results of myocardial revascularization with or without cardiopulmonary bypass in octogenarians. The risk of cerebrovascular disease was found to be diminished by the use of OPCAB. Yokoyama and colleagues [3] reported that OPCAB for elderly patients could obviate the incidence of postoperative complications, whereas Beauford and colleagues [4] also reported that OPCAB for octogenarians could decrease the incidence of postoperative complications other than atrial fibrillation, compared with younger patients.
Meanwhile, the influence of the selection of graft material on late outcome has been a matter of controversy for many years, aside from the issue of whether or not to use cardiopulmonary bypass [12–19]. Previous reports had found the ITA to have the most favorable late patency owing to a biochemical effect [26]. Furthermore, although the conclusion was not reached in this matter, a number of papers have suggested that other arterial grafts have advantages with respect to vein grafts [12–14]. Muneretto and colleagues [13, 17, 19] and Osswald and associates [30] recently reported the late outcome of off-pump total arterial revascularization in elderly patients. These reports claimed that off-pump total arterial revascularization in the elderly could provide better outcome than could coronary artery bypass grafting with vein grafts, and that vein graft use was a risk factor for recurrent angina or graft failure [13, 17, 19]. Therefore, we adopted the use of OPCAB with arterial grafts only (ie, total arterial OPCAB) for our elderly patients, with positive results so far. Furthermore, concerning the use of the radial artery, there is a discussion of whether the composite graft is superior. Maniar and colleagues [16] reported that the composite graft was superior from the viewpoint of length saving and the benefits of aorta no-touch techniques.
The characteristics of the elderly patients in our study population were as follows: female dominant, anemic, small body size, and cardiomegaly. The proportion of acute myocardial infarction was greater in the elderly population. The reason why the operation time was shorter in the elder group was that we commonly use the bilateral ITA for the younger group. The blood transfusion rate was greater in the elder group.
Predicted risk was measured by the EuroSCORE in each group. This score was devised to construct a stratification system for the assessment of the quality of cardiac surgical care in Europe [22, 23]. It is now regarded as one of the most reliable risk stratification scores for mortality prediction. In the present study, the EuroSCORE was significantly higher in the elder group. However, because the EuroSCORE includes age as one of the risk factors, we subtracted the contribution that pertained to age from the total EuroSCORE. The adjusted score was also significantly larger in the elderly group. This shows that, preoperatively, the older patients have a high-risk background that is independent of age.
Although the hospital mortality rate was higher in group E, none of the causes of deaths were related to cardiac events, and it was much lower than the predicted mortality. Also, the incidences of perioperative myocardial infarction and major adverse cardiac events in the follow-up period did not differ between the two groups. Nor were the incidences of perioperative stroke, postoperative renal failure, mediastinitis, or wound dehiscence different between the two groups. Atrial fibrillation, however, occurred more often in the elderly group. This finding reveals that total arterial OPCAB is as safe for elderly patients as for young patients, in terms of morbidity.
As Morris and colleagues [26] described, ITA is most reliable graft even for the elderly patients. We preferred the bilateral use of ITA. However, for the high-risk patients, to reduce the operation time and the amount of bleeding, we used unilateral ITA and radial artery. This is because bilateral ITA was used for fewer patients in the elderly group. Arteries other than ITA or radial artery were not generally used. As the left anterior descending coronary artery is the most important target, we used the ITA for this lesion. Another matter of concern is the quality of the bypass graft. The number of anastomoses and the complete revascularization rate were not different between the two groups. Meanwhile, the graft patency rate was not different between the two age groups. Furthermore, total revascularization rate is more important. Osswald and colleagues [30] reported that incomplete revascularization is a risk factor for early death, in a retrospective study. In the present study, the total revascularization rate was not different between the two groups.
This study has several limitations, including its small sample size and its retrospective nature. Although arterial grafting is thought to be superior to venous grafting in terms of long-term patency, the follow-up period of this study was too short to make a conclusive determination. We could only confirm that elderly patients can undergo total arterial OPCAB as safely as can younger patients; the superiority of total arterial OPCAB will remain unknown until long-term results are available.
The results of this study demonstrate that total arterial OPCAB for elderly patients provides excellent early outcomes. Although extended follow-up is mandatory to confirm the superiority of arterial grafts to vein grafts, we preferentially approach all patients as potential candidates for total arterial OPCAB.
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Abstract
Introduction
