Ann Thorac Surg 2003;75:1161-1164
© 2003 The Society of Thoracic Surgeons
Original article: cardiovascular
Patency rates of three arterial grafting patterns to the left anterior descending and diagonal coronary arteries in symptomatic patients
Martin Brueck, MDa*,
Wilfried Kramer, MDa,
Paul R. Vogt, MDb,
Werner G. Daniel, MDc,
Harald Tillmanns, MDa,
Josef Ludwig, MDc
a Department of Cardiology, University of Giessen, Giessen, Germany
b Department of Cardiothoracic Surgery, University of Giessen, Giessen, Germany
c Department of Cardiology, University of Erlangen, Erlangen, Germany
Accepted for publication November 1, 2002.
* Address reprint requests to Dr Brueck, Department of Cardiology, Clinic of Wetzlar-Braunfels, Forsthausstrasse 1, D-35578 Wetzlar, Germany
e-mail: martinbrueck{at}t-online.de
 |
Abstract
|
|---|
BACKGROUND: The use of internal thoracic arteries is an established method for treating coronary artery disease because of their excellent long-term patency rates. However, these results mainly referred to the left internal thoracic artery (LITA) grafted to the left anterior descending coronary artery (LAD). The aim of this study was to compare the patency rate of the LITA after its placement to the diagonal branch.
METHODS: A total of 302 patients (median age 65 years) with previous arterial revascularization were retrospectively enrolled in the study. We compared LITA grafts to the LAD with those to the diagonal branch and with sequential LITA grafts to both vessels with respect to the patency rate over a median follow-up of 39 months after prior operation. Angiography was performed for recurrent angina.
RESULTS: The average occlusion/stenosis rate of saphenous vein and LITA grafts were 43.1% and 14.1%, respectively (p < 0.0001). Of the 302 patients, 248 had received a single LITA graft to the LAD; 21 patients, a single LITA graft to the diagonal branch; and 33 patients, a sequential LITA graft to both vessels. Thirty-three LITA grafts to the LAD (13.3%), three LITA grafts to the diagonal branch (14.3%), and six sequential LITA grafts to the LAD and the diagonal branch (18.2%) were occluded or stenosed more than 50%, respectively (p = 0.68). Seventy-nine percent of LITA graft stenoses were located at the peripheral anastomosis.
CONCLUSIONS: Patency of single LITA grafts to the diagonal branch or sequential LITA grafts to the LAD and diagonal branch were comparable to single LITA grafts to the LAD. Most stenoses of LITA grafts were located at peripheral anastomoses.
|
Introduction
|
|---|
Coronary artery bypass grafting (CABG) is an established method for treating coronary artery disease (CAD), resulting in decreased angina pectoris and prolonged life, at least in a selected group of patients [1, 2]. The use of arterial grafts, such as the internal thoracic artery (ITA), is a basic element of modern bypass operations because of their superior long-term patency rate compared with saphenous vein grafts (SVGs). Thus, angiographic studies revealed that only 10% of the ITA used as arterial conduits were stenosed or occluded 10 years postoperatively compared with 50% to 60% of SVGs [3, 4]. This excellent long-term patency rate is due to the properties of vasoregulation and resistance to thrombosis and arteriosclerosis of the ITA.
However, these results referred to revascularization of the left anterior descending coronary artery (LAD). Sometimes, for anatomic or functional reasons, such as smallness or severe arteriosclerosis of the LAD or lack of vitality of the anterior myocardial wall, arterial revascularization of the diagonal branch is necessary. However, coronary arteries are characterized by different risks of developing stenoses, and data on patency rates of ITA grafts to the diagonal branch are not available. Therefore, the aim of this study was to compare retrospectively the long-term patency rate of the left ITA (LITA) after single revascularization of the LAD with single LITA grafts to the diagonal branch with sequential LITA grafts to both vessels.
|
Patients and methods
|
|---|
Patient population
We retrospectively examined 302 patients (65.1 ± 7.8 years, 242 males) with prior CABG procedures and arterial revascularization of the left coronary artery by means of the LITA, who had undergone cardiac recatheterization due to symptomatic CAD between January 1995 and September 2001. For the years in which these patients had their CABG, 700 to 800 patients were operated on each year. More than 91% of them received an ITA graft. The median time between operation and angiography was 39 months (range, 1 to 237 months). These patients were distributed into the following three groups: in group I, LITA was used for revascularization of the LAD; in group II, LITA was used for revascularization of the diagonal branch; and in group III, patients had received a sequential arterial conduit of the LITA to the LAD and the diagonal branch.
Angiography procedure
Coronary angiography was performed according to current standard techniques. Vascular access was obtained using the femoral approach with the Seldinger technique and a 6F or 7F catheter. All native coronary arteries and coronary artery bypass grafts were injected with dye, and we obtained at least four views of the left, two views of the right system, and two views of the bypass grafts. Stenosis of bypass grafts was defined as lumen reduction of more than 50% assessed visually. The analysis of coronary angiographies was done by three experienced cardiologists. The location of stenosis was differentiated into ostium or proximal anastomosis; proximal, middle, and distal portion of the graft; and distal anastomosis.
Statistical analysis
Baseline characteristics were summarized for categorical variables with frequencies and percentages and for continuous factors with medians and interquartile ranges. Frequency data were analyzed using the 
2 test, and median values were compared using analysis of variance. Differences were considered statistically significant at a p level less than 0.05. Statistical tests were performed using commercially available software (SPSS version 8.0; SPSS Inc, Chicago, IL).
|
Results
|
|---|
Baseline characteristics
We treated 302 patients by 901 grafts with 1005 peripheral anastomoses (3.3 per patient), including 599 SVGs with 670 peripheral anatomoses (2.2 per patient) and 302 LITA grafts with 335 peripheral anastomoses (1.1 per patient). Two hundred eighteen SVGs (32.5%) were occluded, and 71 were stenosed more than 50% (10.6%) resulting in an incidence of compromised SVGs of 43.1%. However, occlusion (6.9%) and stenosis (7.2%) rates of LITA grafts were significantly lower (p < 0.0001) compared with SVGs (Fig 1).
View larger version (12K):
[in this window]
[in a new window]
|
Fig 1. Incidence of compromised saphenous vein grafts (SVG) and left internal thoracic artery (LITA) grafts
|
|
Of the 302 patients who had arterial coronary revascularization, LITA was grafted to the LAD in 248 patients, to the diagonal branch in 21 patients, and sequentially to both vessels in 33 patients. The median and mean interval between operation and angiography of patients with a single LITA graft to the LAD were 39 and 51 ± 43 months, respectively, with a single LITA graft to the diagonal branch 39 and 45 ± 34 months, respectively, and with a sequential LITA graft to the LAD and the diagonal branch 38 and 43 ± 39 months, respectively. Patients treated with LITA grafts to the diagonal branch were significantly younger than those in the other two groups (p = 0.02). Of the other baseline demographics, angina class and risk factors were similar in the groups. They are listed in Table 1.
Forty patients (13.2%) had a left ventricular ejection fraction less than 30%. All the patients were on antianginal therapy.
Location of graft stenosis
One third of SVG stenoses >50% occluded were at the distal anastomosis. The proximal anastomosis and distal, middle, and proximal portion of SVGs were involved in 16%, 14%, 15%, and 21% of the cases, respectively. In contrast, most stenoses (79%) of LITA grafts were located at the distal anastomosis (Table 2).
At the time of the angiography 33 (13.3%) single LITA grafts to the LAD, three (14.3%) single LITA grafts to the diagonal branch, and six (18.2%) sequential LITA grafts to the LAD and the diagonal branch were compromised (occluded or stenosed > 50%) (p = 0.68; Fig 2).
In the four cases of sequential LITA graft occlusion, both peripheral anastomoses were included. Of the two stenosed sequential LITA grafts, both peripheral anastomoses were implicated in only one case.
View larger version (46K):
[in this window]
[in a new window]
|
Fig 2. Incidence of compromised left internal thoracic artery (LITA) grafts. (LAD = left anterior descending coronary artery; RD = diagonal branch.)
|
|
Contrary to recommendations of the cardiologists, two different vessels have been bypassed (LITA to the diagonal branch instead of the LAD). Angiographically, there were no abnormalities concerning the coronary artery anatomy in these cases except that the lumen diameter of the LAD and the diagonal branch were similar.
Concerning the therapeutic implications of the current study, 15 of 42 patients (35.7%) with compromised LITA grafts underwent percutaneous coronary intervention (PCI), with successful intervention in 91%; 18 patients (42.9%) were advised to have a second CABG. The remaining 9 patients (21.4%) were treated medically.
|
Comment
|
|---|
Arterial conduits have been introduced into CABG in an attempt to overcome the limitations of SVGs containing acute thrombosis, intimal hyperplasia, and progression of arteriosclerosis. The ITA in particular has gained widespread acceptance, because it usually does not develop late postoperative arteriosclerosis, and its patency rate after 10 years remains up to 90%, compared with 50% to 60% for SVGs [3–7].
Long-term survival in patients revascularized with one or both ITAs is enhanced because of decreased clinical events compared with patients who received only SVGs. For patients with single-vessel disease confined to the proximal LAD, the Medicine, Angioplasty, or Surgery Study [8] suggested that ITA bypass operations resulted in significant reduction in angina and ischemia compared with either PCI or medical therapy. The survival advantage increased with time, suggesting that the initial selection of the conduit is a more important factor for survival than problems occurring long after the operation, such as progression of CAD [9]. Accordingly, patients with diabetes or on long-term hemodialysis have better long-term survival after CABG than PCI, but the survival advantage occurs mostly with ITA grafting [10, 11].
The outstanding patency rates of the LITA were obtained only in the case of grafting to the LAD. However, the lack of long-term patency rates of the ITA grafted to the diagonal branch or sequentially to the LAD and the diagonal branch has limited the definite assessment of this kind of operative procedure so far. Other arterial conduits, such as the gastroepiploic artery, the radial artery, and the inferior epigastric artery, have also been proposed for CABG, but long-term patency rates are lacking, too.
The current retrospective study found that patency rates (stenosis < 50%) were comparable (p = 0.68) for a single LITA grafted to the LAD (86.7%), single LITA grafts to the diagonal branch (85.7%), and sequential LITA grafts to the LAD and the diagonal branch (81.8%). Technical aspects regarding the type of anastomosis seem to be the most important factor of graft patency and recurrence of symptoms. In a report of PCI of 32 ITA graft lesions, 12 (37.5%) were in the midportion of the artery and 20 (62.5%) were at the anastomosis [12]. In agreement with those results, we found that 79% of the LITA graft stenosis was located at distal anastomosis.
In the current study the rate of compromised LITA grafts was rather high compared with other rates in the literature [3–7]. This is likely a result of the negative selection of the study population. Only patients with recurrent angina pectoris after CABG were enrolled.
One of the most important questions surgeons face is whether sequential grafting of the LAD and the diagonal branch by the LITA is indicated. This sequential procedure requires high surgical skill, and by performing a side-to-side conjunction with the diagonal branch proximal to the LAD anastomosis, the sequential technique could even endanger the most important anastomosis to the LAD. It has been shown that nonsurgical treatment (ie, catheter-based intervention) of bifurcational coronary lesions is associated with a restenosis rate of 30% to 40% regardless of the technique used [13]. The rate of compromised sequential ITA grafts to the LAD and the diagonal branch was 18.2% in the current study. Therefore, sequential ITA grafting to the LAD and the diagonal branch in the case of bifurcational stenosis seems to be a rational option, especially if minimally invasive CABG and total arterial revascularization are the goals. In all other cases of conventional CABG for CAD, the best surgical treatment of stenoses of the LAD and the diagonal branch—single versus sequential grafting—remains unknown.
Limitations
There are several important potential limitations inherent in any observational study. The study included a selected negative population, which consisted of patients with CAD who had angina pectoris after CABG. Therefore, our conclusions cannot be generalized to all patients with CAD and previous CABG. The study did not use a randomized design, but no study to date in this field has been randomized. A randomized trial would be unethical because of the prognostic relevance of the LAD. Our analysis is based on a retrospective study design, and it is possible that selection bias for a particular choice of coronary artery for LIMA grafting may have occurred. Another major limitation is the restricted number of patients with LITA grafts to the diagonal branch or the LAD and the diagonal branch, leading to a possible lack of difference in patency rates. Thus, our conclusions are tentative but suggest that the diagonal and sequential grafts are not dramatically worse. Furthermore, the results may be dependent on surgical skill and experience, but these factors cannot be eliminated. We did not perform quantitative assessment of the angiograms; however, for detecting an occluded LITA graft, quantitative assessment of the angiograms is not required, and significant LITA graft stenoses are generally assessable by direct viewing.
Single or sequential LITA grafting to the diagonal branch confers no increased risk of stenosis or occlusion compared with the LAD. Hence, single or sequential LITA grafts to the diagonal branch seem to be an alternative in cases of smallness or severe arteriosclerosis of LAD or lack of vitality of the anterior myocardial wall. Sequential grafting of the LAD and the diagonal branch by the LITA is a rational option, especially in cases of bifurcational stenosis if minimally invasive CABG and totally arterial revascularization are the goals.
|
Acknowledgments
|
|---|
We gratefully acknowledge Dr Papst of the Justus-Liebig-University Giessen for statistical support and Dr Pittermann for reading the manuscript.
|
References
|
|---|
- Coronary Artery Surgery Study principal investigators, and their associates. Coronary Artery Surgery Study. Circulation 1983;68:939–50
- Varnauskas E., European Coronary Surgery Study group. Twelve year follow-up of survival in the Randomized European Coronary Surgery Study. N Engl J Med 1988;319:332-337.[Abstract]
- Morgenstern D.A., Mills N.L. New conduits for coronary artery bypass. Coronary Artery Dis 1993;4:677-681.[Medline]
- Carrier M. The internal mammary artery: why is it the graft of choice? In: Carrier M, Pelletier LC, eds. Conduits for myocardial revascularization. Austin: RG Landes Co, 1993:34–58
- The VA Coronary Artery Bypass Surgery Cooperative Study Group. Eighteen-year follow-up in the Veterans Affairs Cooperative Study of coronary artery bypass surgery for stable angina. Circulation 1992;86:121-130.[Abstract/Free Full Text]
- Goldman S., Copeland J., Moritz T., et al. Starting aspirin therapy after operation: effects on early graft patency. Circulation 1991;84:520-525.[Abstract/Free Full Text]
- Fitzgibbon G.M., Leach A.J., Kafka H.P., Keon W.J. Coronary bypass graft fate: long-term angiographic study. J Am Coll Cardiol 1991;17:1075-1080.[Abstract]
- Hueb W.A., Bellotti G., de Oliveira S.A., et al. The Medicine, Angioplasty, or Surgery Study (MASS). A prospective, randomized trial of medical therapy, balloon angioplasty, or bypass surgery for single proximal left anterior descending artery stenoses. J Am Coll Cardiol 1995;26:1600-1605.[Abstract]
- Cameron A., Davis K.B., Green G., Schaff H.V. Coronary bypass surgery with internal-thoracic-artery-grafts–effects on survival over a 15-year period. N Engl J Med 1996;334:216-219.[Abstract/Free Full Text]
- Bypass Angioplasty Revascularization Investigation (BARI) investigators. Comparison of coronary bypass surgery with angioplasty in patients with multivessel disease. N Engl J Med 1996;335:217–25
- Herzog C.A., Ma J.Z., Collins A.J. Long term survival of dialysis patients in the US after coronary angioplasty, coronary artery stenting, and coronary artery bypass surgery. Circulation 2001;104(Suppl II):703.
- Shimshak T.M., Giorgi L.V., Johnson W.L., et al. Application of percutaneous transluminal coronary angioplasty to the internal mammary artery graft. J Am Coll Cardiol 1988;12:1205-1214.[Abstract]
- Brueck M., Scheinert D., Flachskampf F.A., Daniel W.G., Ludwig J. Sequential versus kissing balloon angioplasty for stenting of bifurcation coronary lesions. Cath Cardiov Interv 2002;55:461-466.
Top
Abstract
Introduction
