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J Thorac Cardiovasc Surg 2008;135:300-307
© 2008 The American Association for Thoracic Surgery
Surgery for Acquired Cardiovascular Disease |
a Department of Thoracic and Cardiovascular Surgery, Seoul National University Hospital, Seoul, Korea
b Department of Thoracic and Cardiovascular Surgery, Halla General Hospital, Jeju-City, Jeju-Do, Korea
Received for publication May 2, 2007; revisions received August 30, 2007; accepted for publication September 11, 2007. * Address for reprints: Ki-Bong Kim, MD, PhD, Department of Thoracic and Cardiovascular Surgery, Seoul National University Hospital, 28, Yeongeon-dong, Jongno-gu, Seoul 110-744, Korea. (Email: kimkb{at}snu.ac.kr).
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Abstract |
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 Top Abstract IntroductionPatients and MethodsStatistical AnalysisResultsDiscussionReferences |
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Methods: Of the 402 patients who underwent off-pump coronary artery bypass surgery between January 1998 and December 2001, 240 patients who received the early, 1-year, and 5-year follow-up coronary angiograms regardless of the patient's anginal symptoms were studied. Morphologic changes of grafts were traced by the FitzGibbon grading system.
Results: Overall graft patency rates (FitzGibbon grade A+B) at early, 1-year, and 5-year angiography were 98.6%, 91.9%, and 88.3%, respectively. Graft patency rates in the left anterior descending artery, left circumflex artery, and right coronary artery territories were similar at early angiograms (P = .162). However, graft patency rate in the left anterior descending artery territory was higher than that in the left circumflex artery and right coronary artery territories at both the 1-year (P < .001) and 5-year (P < .001) angiograms. Of the 31 FitzGibbon grade B arterial grafts (internal thoracic artery and right gastroepiploic artery) at early angiography, 10 became occluded and 19 became grade A at 5-year angiography. In the saphenous vein grafts, grade B lesions gradually increased during the 5 postoperative years (2.6% vs 6.5% vs 13.3%).
Conclusions: Midterm angiographic follow-up demonstrated acceptable patency rates of grafts after off-pump coronary artery bypass surgery. Approximately half of the FitzGibbon grade B arterial grafts in the early angiograms became grade A at 5 years after surgery, but the proportion of grade B saphenous vein grafts gradually increased over the 5 postoperative years.
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Introduction |
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TopAbstractIntroductionPatients and MethodsStatistical AnalysisResultsDiscussionReferences |
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With resurgent interest in off-pump coronary artery bypass grafting (OPCAB) since the mid-1990s, there have been concerns about accuracy and patency of the grafts and the long-term outcome. Some meta-analyses demonstrated that patients undergoing OPCAB demonstrated a lower graft patency than patients undergoing conventional CABG.3,4 Another meta-analysis5 demonstrated a statistically insignificant benefit of conventional CABG over OPCAB for arterial graft patency. However, most of these studies were cross-sectional investigations performed at a defined point in time after surgery. The aims of this study included (1) serial comparison of the graft patency rates in patients who had undergone angiography early postoperatively and 1 and 5 years after OPCAB, (2) evaluation of the graft patency rates based on target territories and revascularization strategies during the 5 postoperative years, and (3) assessment of the serial changes of FitzGibbon B stenotic grafts during the 5 postoperative years.
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Patients and Methods |
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TopAbstractIntroductionPatients and MethodsStatistical AnalysisResultsDiscussionReferences |
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30 days) of the OPCAB patients was 1.24% (5/402). There were 8 late in-hospital deaths (>30 days) and 16 additional deaths during the 5-year follow-up. The early, 1-year, and 5-year follow-up coronary angiograms were performed regardless of the patients' anginal symptoms in 384, 349, and 262 patients, respectively. Of the 402 OPCAB patients, 240 (59.7%) patients who received all the early (postoperative day 1.6 ± 1.6), 1-year (postoperative month 13.2 ± 5.2), and 5-year (postoperative month 59.9 ± 5.7) follow-up angiograms were studied for evaluation of the anastomotic sites and patency of the grafts (
Table 1). Patients who died, refused angiographic evaluation, or had renal function impairment were excluded from the angiographic follow-up. However, patients with renal replacement therapy were included in the angiographic follow-up. Follow-up coronary angiography included 4-plane selective coronary and bypass graft angiography. One physician initially reviewed all the coronary angiograms and consensus was reached after review.
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(grade A = excellent; grade B = fair; grade A+B = patent). Competitive graft flow was defined as distal graft as well as distal native grafted coronary artery flow not clearly opacified as seen by graft angiography, but well-visualized graft flow retrogradely as seen by native coronary angiography; it was classified as a grade B anastomosis.
The basic surgical procedures and principles of OPCAB have been previously described.7 All patients halted aspirin therapy (300 mg/day) the day before the operation and resumed it 1 day postoperatively. The average number of distal anastomoses per patient was 3.1 ± 1.0. The grafts used for distal anastomoses were left internal thoracic artery (ITA) (n = 234), right ITA (n = 164), right gastroepiploic artery (RGEA) (n = 79), radial artery (n = 6), and saphenous vein (n = 57). Almost all of the left ITA grafts (232/234), half of the right ITA grafts (94/164), and the majority of RGEA grafts (74/79) were used as an in situ graft. The majority of ITA grafts (93.4%, 492/527) were used to revascularize the left coronary artery territory, and the majority of RGEA grafts (92.5%, 74/80) were used to revascularize the right coronary artery (RCA) territory. Saphenous vein grafts were used to revascularize the left anterior descending artery (LAD) territory (24.8%, 30/121), left circumflex artery (LCX) territory (40.5%, 49/121), and RCA territory (34.7%, 42/121) without any preference (
Table 2). During the study period, we changed revascularization strategies on the basis of our early patency study after OPCAB.8 Forty-nine (86.0%) of the 57 patients who received vein grafts underwent OPCAB before 2000, and 77.6% (142/183) of the patients who received total arterial grafts underwent OPCAB after 2000.
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The study protocol was reviewed by the institutional review board and approved as a minimal risk retrospective study (Approval No. H-0701-051-196) that did not require individual consent according to the institutional guidelines for waiving consent.
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Statistical Analysis |
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TopAbstractIntroductionPatients and MethodsStatistical AnalysisResultsDiscussionReferences |
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2 test (Pearson 2 and Fisher exact tests). In the analysis of the serial changes over the 5 years' duration, nonparametric 2 test with McNemar examination was used. All results were expressed as mean ± standard deviation or as proportions. |
Results |
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TopAbstractIntroductionPatients and MethodsStatistical AnalysisResultsDiscussionReferences |
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Table 3).
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Table 4, A).
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In the LCX territory, patency rates of ITA grafts decreased significantly between early and 1 year postoperatively, and between 1 year and 5 years postoperatively, and they may be affected by the left ITA graft patency rate. The left ITA graft patency rate decreased significantly between early and 1 year postoperatively (P = .004), and between 1 year and 5 years postoperatively (P = .031). The patency rate of saphenous vein grafts decreased significantly during the first postoperative year (from 91.8% to 71.4%; P = .002), whereas it remained stable between 1 and 5 years (Table 4, C).
In the RCA territory, ITA grafts demonstrated stable patency rates during the 5 postoperative years. RGEA graft patency rates decreased significantly between 1 year and 5 years postoperatively (90.5% vs 81.1%; P =.048). Saphenous vein grafts showed a significantly decreased patency rate during the first postoperative year (from 97.6% to 76.2%; P = .001), but remained stable between 1 and 5 years (Table 4, D).
Changes of the Graft Patency Based on Proximal Techniques
Distal anastomoses constructed with in situ left ITA grafts showed progressively decreased patency rates during the 5 postoperative years, whereas distal anastomoses done with in situ right ITA grafts showed no significant differences in patency rates. Distal anastomoses with the composite right ITA connected to the side of the in situ left ITA showed a decreased patency rate during the first postoperative year (100% vs 95.1%; P = .029), whereas patency showed no significant difference between 1 and 5 years after OPCAB (95.1% vs 92.7%; P = .596). Although distal anastomoses made with in situ RGEA grafts showed no significant differences in patency rates during the first postoperative year, patency decreased significantly between 1 and 5 years after OPCAB. Distal anastomoses with saphenous vein grafts connected to the ascending aorta showed a significantly decreased patency rate during the first year, whereas patency remained stable between 1 and 5 years (
Figure 1).
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Figure 2).
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In the saphenous vein grafts, the proportion of grade B lesions out of patent grafts gradually increased during the 5 postoperative years (2.6% [3/116] vs 6.5% [6/92] vs 13.3% [12/90]; P (early vs 5-year) = .006). All 3 of the grade B saphenous vein grafts in the early angiograms demonstrated a stenosis of greater than 50% at the distal anastomosis site and they became grade A at 1 year after surgery. All 6 of the newly developed grade B saphenous vein grafts seen in 1-year angiograms demonstrated segmental narrowings in the graft trunk. Of the 6 grade B vein grafts in 1-year angiograms, 5 remained grade B and 1 became occluded by 5 years after surgery.
Recurrence of Angina
During the first postoperative year, 10 (4.2%) patients experienced the recurrence of angina. Stenosis or occlusion of a graft was associated with the recurrence of angina in 6 patients, and progression of the native coronary artery disease was the cause of angina in 4 patients whose grafts were all widely patent. During the study period between postoperative years 1 and 5, 31 (12.9%) additional patients experienced the recurrence of angina. Stenosis or occlusion of a graft was associated with the recurrence of angina in 18 patients, and progression of the native coronary artery disease was the cause of angina in 13 patients.
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Discussion |
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TopAbstractIntroductionPatients and MethodsStatistical AnalysisResultsDiscussionReferences |
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With resurgent interest in OPCAB since the mid-1990s, there have been concerns about accuracy and patency of the grafts and the long-term outcome. Two meta-analyses using randomized studies demonstrated that patients undergoing OPCAB demonstrated a lower graft patency than patients undergoing conventional CABG.3,4 Those differences were mainly attributable to the lower saphenous vein or radial artery graft patency rates. A significantly lowered patency for saphenous vein grafts than for ITA grafts was suggested to result from the type of graft, presence of hyperlipidemia, the exposure and quality of stabilization, and increased procoagulant activity in OPCAB patients.7,9,10 Another meta-analysis5 that included two more randomized trials11,12 found a statistically insignificant benefit of conventional CABG over OPCAB for arterial graft patency and a statistically significant 28% increase in venous graft occlusion with OPCAB relative to conventional CABG. One study,13 which reviewed the articles published from 1972 through 1998, examined outcomes of left ITA grafting to the LAD. The early (1 month postoperatively) and 1-year patency rates of left ITA grafts in conventional CABG have been reported to be between 94% and 99% and 88% and 93%, respectively. The present study showed that the early and 1-year patency rates of left ITA grafting to the LAD in OPCAB were 99.5% and 98.2%, respectively, both of which were not apparently inferior to those of conventional CABG.
In contrast to most of the previous studies investigating the patency of grafts by cross-sectional study at a specific time point, we performed coronary angiography in all of the 240 patients early postoperatively and 1 and 5 years after OPCAB to trace the changes of the anastomoses and grafts in the same patient population. In the present serial study, overall (grade A+B) graft patency rates early and 1 and 5 years postoperatively decreased significantly when analyzed by comparison between early and 1-year rates, and between 1-year and 5-year rates. We used the 2 test with McNemar examination, instead of the simple 2 test, because the present study analyzed the morphologic change of anastomotic sites in the same patient group. Although ITA grafts demonstrated a greater than 90% patency rate at 5 years postoperatively, the patency rate of ITA grafts also decreased significantly during the follow-up period. RGEA grafts showed a significantly decreased patency rate between 1 year and 5 years. Saphenous vein grafts showed a significantly decreased patency rate during the first postoperative year; however, their patency rate remained stable between 1 year and 5 years. The occlusion rate of saphenous vein grafts has been reported to be 2% to 2.5% per year between the first and fifth postoperative years.14 The present study demonstrated that the patency of vein grafts remained stable during the period (76.0%–74.4%; P = not significant), which was similar to another serial study for conventional CABG.15 This study supports the idea that very little change occurs between 1 and 5 years in the overall patency rate of saphenous vein grafts.16
Like others,17 we demonstrated that graft patency rates of the LAD territory were higher than those of the LCX or RCA territories at both 1-year and 5-year angiograms, even though graft patency rates in the three territories were similar at early postoperative angiography. In the LAD territory, there were no significant differences in graft patency rates between early and 1 year, or between 1 year and 5 years postoperatively. Although the number of saphenous veins grafted for the LAD territory was small, saphenous vein grafts also demonstrated stable patency during the 5 postoperative years. The RCA territory, where grafts other than the ITA graft were commonly used, showed a lower patency rate than other territories in some studies.18,19 Other studies20,21 demonstrated lower patency rates of right ITA grafts in the RCA territory; however, we did not observe that finding in the RCA territory. Right ITA grafts demonstrated stable patency rates during the 5 postoperative years. RGEA grafts that were preferentially used as in situ grafts for revascularization of the RCA territory showed significantly decreased patency rates between 1 year and 5 years postoperatively despite excellent early and 1-year patency rates. Saphenous vein grafts showed significantly decreased patency rates during the first postoperative year, in contrast to a previous study demonstrating a comparable patency of saphenous vein grafts to ITA grafts in the RCA territory.17
When the patency rates were analyzed on the basis of the proximal technique, in situ left ITA grafts showed significantly decreased patency rates during the 5 postoperative years. Because two thirds (71.9%, 218/303) of in situ left ITA grafts were used to revascularize the LAD territory and the remainder for the LCX territory, decreased patency rates of in situ left ITA grafts in the LCX territory might have affected the overall patency rate of in situ left ITA grafts. In the LCX territory, the majority of the left ITA grafts (98.8%, 85/86) were used as in situ grafts whereas the majority of the right ITA grafts (96.4%, 81/84) were used as composite grafts. In situ left ITA grafts may have to bend posteriorly and sometimes be pushed by the pericardial margin when grafting the posterior coronary artery, which may decrease the patency rate in the LCX territory. On the basis of our experience, we have changed our revascularization strategy in OPCAB by avoiding the use of vein grafts if possible and performing total arterial revascularization using composite graft rather than bilateral in situ ITA grafts.
The present study demonstrated that the proportion of grade B arterial grafts (ITA and RGEA) remained stable (5.1% vs 5.5% vs 6.0%) whereas the proportion of FitzGibbon grade B grafts increased in vein grafts (2.6% vs 6.5% vs 13.3%) during the 5 postoperative years. The decreased patency of arterial grafts in the present study seemed to be partly associated with the status of the native coronary artery, because most late occlusions (9/10) of grade B arterial grafts at early angiography were associated with moderate stenosis (<80%) of the native vessel; in contrast, 12 of the 13 newly developed grade B saphenous vein grafts after 1 year demonstrated segmental narrowings in the graft trunks, and 1 graft demonstrated stenosis at the distal anastomosis site. The decrease in vein graft patency was suggested to be associated with disease in the graft itself, demonstrated by segmental narrowing in the vein graft trunks. All 3 grade B saphenous vein grafts in the early angiograms demonstrated a stenosis of more than 50% at the distal anastomosis site. Some of the anastomotic site stenoses seen in the early angiograms might result from local tissue edema, because 9 of the 13 anastomotic grade B ITA grafts and all 3 grade B saphenous vein grafts became grade A at 1 year after surgery.
There are limitations to the present study that must be recognized. First, the present study was a retrospective observational study of a single surgeon in a single institution and was not performed in a randomized manner with regard to the type of conduits and the target vessels; the majority of ITA grafts were used to revascularize the left coronary territory and the majority of RGEA grafts were used to revascularize the RCA territory. These might serve as confounding variables. Second, we changed the revascularization strategies during the study period. A majority of patients who received vein grafts underwent OPCAB in the early study period and most patients who received total arterial grafts underwent OPCAB in the latter part of the study period, which would affect the results. Third, we might have overestimated the patency rates by selecting the patients who survived and had angiograms performed 1 and 5 years after surgery. Fourth, inasmuch as we performed OPCAB in most patients (77.0%) during the study period, it was difficult to obtain an on-pump control group to determine the difference between OPCAB and on-pump CABG. However, when we compared the present data with our previous serial study for conventional CABG (n = 109),15 there were no differences in 1-year and 5-year graft patency rates between the OPCAB and conventional CABG groups (ITA, 95.6% vs 97.9% at 1 year, 92.4% vs 90.3% at 5 years; saphenous vein, 76.0% vs 82.4% at 1 year, 74.4% vs 80.2% at 5 years) (P = not significant).
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Footnotes |
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References |
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TopAbstractIntroductionPatients and MethodsStatistical AnalysisResultsDiscussionReferences |
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lu SN, K¹rali K, Güler M, Toker ME, 
pek G, I
¹k Ö, et al. Midterm angiographic assessment of coronary artery bypass grafting without cardiopulmonary bypass. Ann Thorac Surg 2000;70:844-849.This article has been cited by other articles:
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  R. D. Lopes, R. H. Mehta, G. E. Hafley, J. B. Williams, M. J. Mack, E. D. Peterson, K. B. Allen, R. A. Harrington, C. M. Gibson, R. M. Califf, et al. Relationship Between Vein Graft Failure and Subsequent Clinical Outcomes After Coronary Artery Bypass Surgery Circulation, February 14, 2012; 125(6): 749 - 756. [Abstract] [Full Text] [PDF]
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 H. Y. Hwang, J. S. Kim, K. R. Cho, and K.-B. Kim Bilateral Internal Thoracic Artery In Situ Versus Y-Composite Graftings: Five-Year Angiographic Patency and Long-Term Clinical Outcomes Ann. Thorac. Surg., August 1, 2011; 92(2): 579 - 586. [Abstract] [Full Text] [PDF]
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 T. Athanasiou, S. Saso, C. Rao, J. Vecht, J. Grapsa, J. Dunning, M. Lemma, and R. Casula Radial artery versus saphenous vein conduits for coronary artery bypass surgery: forty years of competition -- which conduit offers better patency? A systematic review and meta-analysis Eur J Cardiothorac Surg, July 1, 2011; 40(1): 208 - 220. [Abstract] [Full Text] [PDF]
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 S. Manabe, T. Fukui, M. Tabata, T. Shimokawa, S. Morita, and S. Takanashi Arterial graft deterioration one year after coronary artery bypass grafting J. Thorac. Cardiovasc. Surg., December 1, 2010; 140(6): 1306 - 1311. [Abstract] [Full Text] [PDF]
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K. R. Cho, H. Y. Hwang, J.-S. Kim, D. S. Jeong, and K.-B. Kim Comparison of Right Internal Thoracic Artery and Right Gastroepiploic Artery Y Grafts Anastomosed to the Left Internal Thoracic Artery Ann. Thorac. Surg., September 1, 2010; 90(3): 744 - 752. [Abstract] [Full Text] [PDF]
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K.-B. Kim, J. S. Kim, H.-J. Kang, B.-K. Koo, H.-S. Kim, B.-H. Oh, and Y.-B. Park Ten-year experience with off-pump coronary artery bypass grafting: lessons learned from early postoperative angiography. J. Thorac. Cardiovasc. Surg., February 1, 2010; 139(2): 256 - 262. [Abstract] [Full Text] [PDF]
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 J. G. Byrne, M. Leacche, D. E. Vaughan, and D. X. Zhao Hybrid Cardiovascular Procedures J. Am. Coll. Cardiol. Intv., October 1, 2008; 1(5): 459 - 468. [Abstract] [Full Text] [PDF]
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P < .001 between early and 1 year postoperatively; 