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© 2003 European Association of Cardio-Thoracic Surgery
Early and 1 year angiographic evaluation of graft patency in off-pump coronary bypass surgery via sternotomy
a Department of Cardio-thoracic Surgery, Laennec Hospital, University of Nantes, Nantes 44000, France
* Corresponding author. Tel.: +33-2-40-16-51-33; fax: +33-2-40-16-54-02 Received September 20, 2002; received in revised form December 27, 2002; accepted January 7, 2003
The goal of this study was to evaluate the early and 1 year postoperative angiographic results in patients who underwent coronary revascularisation for multivessel disease on beating heart via sternotomy. One hundred eleven consecutive patients receiving 272 grafts, operated by the same surgeon were studied (2.5 grafts/patient). The quality of the graft and the anastomoses was systematically evaluated by coronary angiography between 1 and 15 days after surgery. Eighty-seven patients (209 grafts) of the initial cohort (78.3%) were repeatedly controlled by angiography between 5 and 24 months. Angiographic findings were studied and classified according to Fitzgibbon classification. Overall early graft patency was 96.4%. Arterial graft patency was 96.4% and vein graft patency was 96.3%  . Of the grafts (88.7%) were Grade A, 21 grafts (7.7%) Grade B and 10 grafts (3.6%) were occluded (Grade O). The second angiographic control revealed a patency rate of 94.8%, arterial graft patency was 95.4% and vein graft patency was 93.8%  : 91.5% of patent grafts were graded (A), 3.3% graded (B) and 5.2% graded (O). A comparison between early and late angiograms revealed: two-stenosis de novo, three-occlusion de novo and decrease or disappearance of the stenosis in 13/21 graft, 11 arterial and two vein grafts (61.9%). In this study, the early and 1 year postoperative patency rate seems to be equivalent to coronary bypass with pump, however, a randomised study is needed to compare both approaches. Most of the stenosis detected at the early coronary angiography could decrease or disappear, especially in arterial grafts.
Key Words: Off-pump coronary artery bypass; Angiography
Despite the technological improvements of cardiopulmonary bypass (CPB) during the past 30 years, CPB is still reported to evoke inflammatory reactions involving multiple organ systems, which may lead to postoperative morbidity [1]. Last few years have seen a surge of interest in off-pump coronary artery bypass grafting (OPCAB) in an attempt to avoid the deleterious effects of CPB. On comparing coronary revascularisation with pump, this is a more challenging technique, (especially grafting of the Circumflex system) [2]. Whether this technique affects the graft patency is yet to be determined. Few data are available concerning early and midterm graft patency in off-pump multivessel coronary artery revascularisation via sternotomy [3–6]. The goal of this study was to evaluate the early and 1 year postoperative angiographic results in patients who underwent coronary artery grafting for multivessel disease on the beating heart via sternotomy.
From January 1998 to July 2000, 134 consecutive patients underwent coronary artery revascularisation without CPB by the same surgeon, 111 patients had postoperative angiographic control, and they represent the cohort patients presented in this study. 2.1. Patients In the beginning of our experience the first 40 patients were selected according to certain anatomic criteria, such as the presence of single or double-vessel disease in the left anterior descending artery (LAD) or right territory, but patients with myocardial hypertrophy or requiring bypass on the Circumflex artery were rejected, later on, all patients were considered as potential candidates for OPCAB.The preoperative cardiac findings and risk factors of the 111 patients (93 males and 18 females, 65.3±9.9 years,range 40–82 years) are listed in Table 1.
2.2. Surgical procedure All operations were carried out through a sternotomy incision, at least one internal mammary artery (IMA) was taken down for all patients but one, with or without saphenous vein (SV). The heart was lifted towards the right by the surgeon and two tapes were stitched to the posterior pericardium. One tape was used to lift the posterior pericardium as much as possible, and the other tape to present the coronary artery, to further assist in providing good presentation of the target arteries on the lateral and inferior aspect of the heart, patients were placed in gentle right decubitus Trendelenburg position. To gain a bloodless field during the performance of the anastomoses, temporary occlusion of the target artery was achieved by silastic bands, a stabiliser was then used to immobilise the site of anastomoses, we started our experience with CTS stabiliser (Cardio thoracic Systems Inc. Cupertino.CA), and then with Angelini stabiliser (Abbey Surgical Limited, Mitcham, Surrey, UK), distal anastomoses was performed before proximal anastomoses using 8/0 polypropylene running suture. When SVG was used, proximal anastomoses was completed immediately after the distal anastomoses using 7/0 polypropylene running suture after lateral aortic clamping., intraluminal shunt (Medtronic clearview) was always used to prevent coronary ischemia during anastomoses. Heparin was administrated before starting the procedure to keep activated clotting time between 250 and 300s. To prevent platelet-aggregation, patients received ASA 160mg daily, 3h after surgery and low molecular weight heparin was continued until the fifth postoperative day. 2.3. Operative data One hundred eleven patients receiving 272 grafts (165 arterial 60.6% and 107 vein grafts 39.3%) were studied (2.5 grafts/patient), operative data are shown in Table 2.
Thirty-four patients had bilateral mammary artery, sequential grafting was performed on 58 coronary arteries (21%), (50 with arterial grafts 18.3%). 2.4. Angiographic follow-up Angiographic control was proposed for all patients during the period of this study, only 111 patients accepted or were able to have angiographic control, we were able to evaluate 272 grafts between 1 and 14 days after surgery. A second angiographic control was proposed for all patients who had a first coronary angiography. Only 87 patients (78.3%)accepted and had a second angiography between 5 and 24 months (mean 12.8±4.3 months). We were able to re-evaluate 209 anastomoses, we reviewed all stenosis which were detected for the first time. All anastomoses in the first and second angiography were classified as described by Fitzgibbon et al. [7].
One patient died of respiratory insufficiency on day 14 (0.9%), two patients had perioperative myocardial infarction (1.8%), two patients had aortic countrepulsation support before surgery because of low ejection fraction. Only 18 patients (16.2%) required blood transfusion, two patients were re-operated for bleed and one patient had postoperative renal failure. We did not encounter any deep wound infection, stroke or TIA Troponin I (cTnI) mean level was 0.55±1.59 (BECKMAN. Coulter, Inc. California). 3.1. Early graft patency Overall early graft patency rate was 96.4%, arterial graft patency rate was 96.4% and vein graft patency rate was 96.3%, there was no significant difference. According to Fitzgibbon et al. classification: 88.7%of the grafts had unimpaired run-off (Grade A), 21 grafts (7.7%)had stenosis reducing graft's calibre <50% of the grafted coronary artery (Grade B) and 10 grafts (3.6%) were occluded. (Table 3)
Sixteen patients had postoperative PTCA, most of them in the beginning of our experience: eight PTCA were performed in accomplishment of surgery for arteries which we were not be able to graft (hybrid revascularisation): five on the lateral territory, two on the right coronary artery and one on PDA. Another two PTCA were performed for severe stenosis at the anastomotic site on the LAD, two PTCA on the native arteries because of occluded grafts on the OM and the RC arteries, one for severe stenosis on a vein valvule for the OM, one for a steal syndrome by a large first collateral of the LIMA, one for kinking in a sequential anastomoses by the LIMA, and one stenosis on the LIMA by a clip. 3.2. Midterm graft patency The second angiographic control revealed a patency rate of 94.8%, arterial graft patency rate was 95.4% and vein graft patency rate was 93.8%, again there was no significant difference in patency rate between arterial and vein grafts. According to Fitzgibbon et al. classification: 91.9%of the grafts were Grade A, 3.3% of the grafts Grade B and 5.2% were occluded. All stenosis Grade B were re-evaluated by the second angiography. A comparison between the first and the second angiograms revealed: two new stenosis which were not stenotic at the time of the first angiography (one arterial graft and one vein graft) and three occlusion de novo (three vein grafts). Thirteen out of the 21 stenosis detected in the first angiograms were decreased or disappeared (61.9%), especially in arterial grafts (11/13), it also revealed, disappearance of one stenosis in the native coronary artery, the graft was occluded. 3.3. Late clinical follow-up We reported three midterm deaths (>30 days), one patient died 6 months after surgery because of chronic heart failure, one patient died after 9 months because of hepatic cancer and one patient died after 11 months because of stroke. Ninety-nine patients (89.1%) were free of angina at the time of second angiography, PTCA was performed successfully for three patients at the anastomotic sites. Ninety-eight patients were in New York Heart Association functional class I, five patients class II, three patients class III and one patient class IV.
Since the first Beating heart revascularisation launched by Kolsov in the 1960s [8], many authors have developed clinical experience with OPCAB during last decade, to avoid deleterious effects of CPB, especially in high risk patients [9–12]. In the other hand, this technique is more challenging especially for the Circumflex artery grafting [2], but whether this affects graft patency remains to be determined. Coronary angiography still considered the method of choice for evaluating coronary graft patency, but it is an invasive test, therefore, a few data, of early and midterm patency in off-pump coronary artery bypass by sternotomy is available. Early patency rate reported by Fitzgibbon et al. for arterial grafts (AG) was 95 and 88% for vein grafts (VG) [7], Ivert et al., Berger et al. fond 94 and 98.8%, respectively for AG. The midterm (>1 year) patency rate for AG was reported as 80 to 93% and 75% for SVG [7,13,14]. In off-pump CABG, arterial patency rate was reported as 93.7–98% [15,3,8]. Patency rate for AG were almost reported higher than SVG patency rate, but in our study, early AG patency rate was 96.4%, and SVG patency rate was 96.3% and the difference was not significant. Even in 1 year angiographic control, patency rate for AG was 95.4% and 93.8% for SVG and the difference was also not significant. Although, intraluminal coronary shunts have been reported to injure the vascular endothelium, we did not find any stenosis caused by the shunts in this study. We think that shunts may play a role to avoid anastomotic stenosis, and running suture (8/0) around the shunt allows a fine anastomoses and avoid narrowing, especially in coronary arteries with small diameter. In early follow-up, stenosis rate (Grade B) in AG was 8.4% and 6.5% in SVG and the difference was not significant. Most of these stenosis decreased or disappeared in the second control (Table 4). We remarked that most of the stenosis were on the anterior territory when the LIMA was used as a sequential graft (13/21). This, could be explained by the small diameter at the end of the LIMA when it is used as sequential graft, with edema and spasm especially in arterial grafts more easily provoked in the early postoperative period. We also used to do criss-cross anastomoses on the diagonal arteries in sequential graft which could be stenotic, we do now side to side anastomoses.
We believe that only patients with clinical signs of myocardial ischemia are candidates for re-intervention, based on this experience we recommend a PTCA first. In conclusion, off-pump multivessel coronary artery bypass via sternotomy is safe and effective, sternotomy can offer a good access to all coronary arteries. Early and midterm postoperatively patency rate in off-pump coronary grafting seems to be, in this study, equivalent to coronary bypass grafting with pump, however, a randomised study is needed to confirm this results. In this study most of stenosis detected in the early angiograms were decreases or disappeared especially in arterial grafts, only patients with evidence of myocardial ischemia signs must be proposed for re-intervention.
Conference discussion Dr R. Dion (Leiden, The Netherlands): There were only 111 controls out of 131 patients for the first restudy? What were the criteria for the selection? Dr Alhabash: We tried to control all patients systematically. Dr R. Dion: Why did you not get a control for all patients? Dr Alhabash: Because two patients had postoperative renal failure, one patient died, and the others refused this control. Dr A. Boening (Kiel, Germany): You have shown that some stenoses in the arterial grafts have decreased. Can you tell in advance which kind of stenosis will decrease and which will not? Dr Alhabash: depending on the diameter of the artery for example? Dr Boening: Something like that, yes. Dr Alhabash: No we can't precise which stenosis will decrease or not, but most of the stenoses were on the LDA. And for sequential grafts, I think there was certainly a technical problem that we modified later on. In the beginning we did a very small incision in the sequential grafts, and we used to do crisscross anastomosis, later on we changed for a longitudinal and side-to-side anastomosis with a little bit wider incision. I think, especially for the arterial grafts, stenoses is also due to edema and inflammatory reaction which disappeared later. Dr R. Dion (Leiden, The Netherlands): In the case of high risk revascularization, what was the reason you started with surgery and performed PTCA after? Dr Alhabash: Because in the beginning of this experience, we were not able to do circumflex or all branches on off-pump. So with patients with high-risk factors, we decided to do one or two vessels, the easier, and then to perform PTCA for the others. Dr Dion: And at which interval after the operation did you perform PTCA? Dr Alhabash: Immediately after surgery.
ICVTS on-line discussion Author: Dr. Hitoshi Hirose, MD, FICS, Cleveland Clinic Foundation, Thoracic and Cardiovascular Surgery, 2600 Overlook Rd. #312, Cleveland, Ohio 40019, USA Date: 22-Mar-2003 08:21 Message: The finding was significant that most of the stenosis detected at the early angiography may decrease in the internal mammary artery grafts (IMA). I further speculate your finding that percutaneous transluminal angiography (PTCA) should not be done based on the early angiographical findings but based on the symptoms. The stenosis found in the early angiogram should be repeated within one year after initial angiogram to see whether or not the stenosis has regressed. These stenosis regression phenomena can be observed not only the IMAs, which the authors mostly evaluated in this paper, but also in the gastroepiploic artery. We speculate that the factors influencing graft stenosis regression are not only the technique of the anastomosis but also the flow of the native coronary artery. I have some questions for you. Graft stenoses we have observed are usually at the anastomosis on the arterial grafts and at the middle segment where the valves are located on the venous grafts. In addition to the anastomosis stenosis, arterial graft may become diffuse stenosis, so called string signs. Where were the stenoses you have encountered located? Have you seen string sign? If you saw string sign, did you observe that any string signs improved during your study period? At last, your experience was limited to the IMA and saphenous vein grafting. It would be difficult to conclude, "most of the stenosis at the early coronary angiography could decrease or disappear, especially in arterial grafts."
Presented at the 16th Annual Meeting of the European Association for Cardio-thoracic Surgery, Monte Carlo, Monaco, September 22–25, 2002. doi:10.1016/S1569-9293(03)00004-5
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Abstract
1. Introduction