Off-Pump Bilateral Versus Single Skeletonized Internal Thoracic Artery Grafting in Patients With Diabetes

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1 Off-Pum Bilateral Versus Single Skeletonized Internal Thoracic Artery Grafting in Patients With Diabetes Takeshi Kinoshita, MD, Tohru Asai, MD, PhD, Osamu Nishimura, MD, Tomoaki Suzuki, MD, PhD, Atsushi Kambara, MD, and Keiji Matsubayashi, MD, PhD Division of Cardiovascular Surgery, Shiga University of Medical Science, Setatsukinowa, Otsu, Jaan Background. We comared the outcomes in roensity score-matched atients with diabetes undergoing off-um coronary artery byass grafting using skeletonized bilateral or single internal thoracic artery (ITA) and assessed any benefit of bilateral ITA grafting for outcomes. Methods. Among 770 consecutive atients undergoing isolated coronary artery byass graft surgery (99.2% by off-um technique without conversion to cardioulmonary byass), 423 atients had diabetes mellitus. After excluding atients who were older than 85 years of age (n 10) or had only one target vessel at the left coronary area (n 9), 170 airs were matched using roensity scores created on the basis of 12 reoerative factors. Results. Excet for 1 atient, bilateral ITA was anastomosed to the left coronary system. Postoerative serum glucose was well controlled in both grous. The rate of dee sternal infection was similar between the grous. The mean observation eriod was 3.2 years. The 5-year survival free from overall death in bilateral versus single ITA grafting was 87.5% versus 70.8% (log-rank test 0.01). For freedom from cardiac death, the resective rate was 92.1% versus 78.7% ( 0.01). For freedom from cardiac event, the resective rate was 91.0% versus 72.6% ( 0.01). In multivariate Cox models, bilateral ITA grafting was significantly associated with a lower risk for overall death (hazard ratio, 0.45; 95% confidence interval, 0.22 to 0.89; 0.02), cardiac death (hazard ratio, 0.43; 95% confidence interval, 0.21 to 0.87; 0.02), and cardiac event (hazard ratio, 0.42; 95% confidence interval, 0.20 to 0.85; 0.02). Conclusions. Off-um skeletonized left-sided bilateral ITA grafting is associated with better mid-term outcomes than single ITA grafting, without increasing the risk of dee sternal infection. (Ann Thorac Surg 2010;90:1173 9) 2010 by The Society of Thoracic Surgeons Diabetes mellitus is an indeendent risk factor of oor rognosis after coronary artery byass grafting [1 3]. Otimal oerative strategy to imrove outcome of this subset has not been determined. Bilateral internal thoracic artery () grafting has been reorted to rovide better long-term results than single internal thoracic artery () grafting [4 10]. Several investigators assessed the survival benefit of grafting in atients with diabetes with conflicting results [11 15]. The urose of our study was to comare mid-term outcomes in roensity score-matched cohort of diabetic atients undergoing off-um coronary artery byass grafting using skeletonized or and to quantify any benefit of grafting for mid-term outcomes. Patients and Methods Acceted for ublication May 19, Address corresondence to Dr Kinoshita, Shiga University of Medical Science, Setatsukinowa, Otsu, , Jaan; kinotake@ belle.shiga-med.ac.j. All atients had reviously granted ermission for use of their medical records for research uroses. This study was aroved by the institutional review board. Between January 2002 and December 2009, 770 consecutive atients underwent isolated coronary artery byass grafting by a single surgeon (T.A.) at our institution. Excet for 1 reoerative case and 5 salvage cases in which ercutaneous cardioulmonary suort was reoeratively introduced, all atients underwent myocardial revascularization using the off-um technique without conversion to cardioulmonary byass during oeration. Of this cohort, 423 atients affected by diabetes mellitus underwent off-um coronary artery byass grafting using (n 203) or (n 220) with comlementary sahenous vein or gastroeiloic artery. We excluded atients who would not be otential candidates for grafting; that is, atients older than 85 years of age (n 10), and those whose coronary anatomy resented only one target vessel in the left coronary artery system (n 9). The remaining 404 atients who were otentially suitable for grafting were included in the resent study. Proensity scores were created to quantify the likelihood that a given atient would receive grafting. Univariate analyses were erformed to examine differences in baseline characteristics between atients who received grafting and those who received grafting (Table 1). Proensity scores were then calculated using a multivariate logistic regression model based on 2010 by The Society of Thoracic Surgeons /$36.00 Published by Elsevier Inc doi: /j.athoracsur

2 1174 KINOSHITA ET AL Ann Thorac Surg SKELETONIZED BILATERAL ITA IN DIABETICS 2010;90: Table 1. Baseline Characteristics in Original Cohort a (n 203) (n 220) Logistic EuroSCORE 7 (6 9) 7 (5 11) 0.29 Age (y) Female 54 (26.7) 49 (22.3) 0.15 Body mass index (kg/m 2 ) Diabetes mellitus 203 (100) 220 (100) 0.99 HgbA1C (%) Tyes of treatment 0.63 Diet 36 (17.7) 42 (19.1) Oral 64 (31.5) 75 (34.1) Insulin 103 (50.7) 103 (46.8) Chronic kidney disease Nondialysis-deendent 35 (17.2) 35 (15.9) 0.45 Dialysis-deendent 25 (12.3) 27 (12.3) 0.64 Duration (y) Smoking 100 (49.3) 114 (51.8) 0.29 Periheral arterial disease 39 (19.2) 30 (13.6) 0.08 Chronic obstructive ulmonary 44 (21.7) 39 (17.7) 0.21 disease Hyerliidemia 100 (49.3) 116 (52.7) 0.37 Hyertension 150 (73.9) 165 (75.0) 0.76 Previous myocardial infarction 100 (49.3) 92 (41.8) 0.09 History of ercutaneous coronary 60 (29.6) 66 (30.0) 0.84 intervention Emergent oeration 15 (7.4) 10 (4.5) 0.21 Coronary anatomy No. target vessels Left main trunk stenosis 50% 56 (30.4) 75 (40.9) 0.04 Left anterior descending artery 202 (100) 220 (100) % Diagonal branch 75% 86 (42.4) 103 (46.8) 0.18 Circumflex artery 75% 142 (70.0) 174 (79.1) 0.04 Right coronary artery 75% 146 (71.9) 157 (71.4) 0.78 Echocardiograhic findings Ejection fraction (%) Ejection fraction 40% 47 (23.2) 50 (22.7) 0.68 LV diastolic dimension (mm) LV systolic dimension (mm) Left atrial dimension (mm) a Data are number (%) or mean standard deviation, or median (interquartile range). bilateral internal thoracic artery; EuroSCORE Euroean System for Cardiac Oerative Risk Evaluation; HgbA1C main fraction of glycosylated hemoglobin; LV left ventricle; single internal thoracic artery. the following 12 reoerative characteristics with a significance level of less than 0.25 in univariate analyses: age, female sex, body mass index, main fraction of glycosylated hemoglobin (HgbA1C), eriheral arterial disease, chronic obstructive ulmonary disease, revious myocardial infarction, emergent oeration, number of target vessels, left main trunk having greater than 50% stenosis, diagonal branch having greater than 75% stenosis, and circumflex artery having greater than 75% stenosis [16, 17]. The area under the receiver oerating characteristic curve was 0.70 (95% confidence interval, 0.65 to 0.75; 0.01). The Hosmer-Lemeshow goodness of fit 2 for this model was 4.28 ( 0.83). Patients who received grafting had a significantly higher mean roensity score than those who received grafting ( versus ; 0.01). There was considerable overla in the roensity scores of atients who received grafting. Each atient who received grafting was matched with a atient who received grafting with the closest roensity score (within 0.03 on a scale of 0 to 1). By matching roensity scores, 170 airs were successfully matched in a 1:1 manner ( grou, n 170; grou, n 170). End Points and Definition The end oints were overall death, cardiac death, and cardiac event. Cardiac death included deaths caused by myocardial infarction, heart failure, or sudden death. Sudden death was defined as a sudden unexected ulseless condition. If unwitnessed, sudden deaths were those in which atients were found dead within 24 hours of having last been seen alive and in a normal state of health. Although sudden death did not always result from cardiac causes, we categorized sudden death into cardiac death because one of the most common underlying reasons for atients to die suddenly from cardiac arrest was coronary artery disease. Documentation of the cause of death was based on information obtained from witnesses, family members, death certificates, hosital records, and autosy records. Cardiac event included myocardial infarction, heart failure, and reeat revascularization. A diabetic atient was defined as one who was diagnosed with diabetes and received diet theray, oral agent, or insulin treatment. Dee sternal infection was defined as any chest wound infection involving the sternum or mediastinal tissues during the follow-u eriod. This definition included infections with exosure of the dee fascia or sternum. Surgical Technique After a median sternotomy, the internal thoracic artery (ITA) and gastroeiloic artery were harvested with the skeletonization technique using an ultrasonic scalel (Harmonic Scalel; Ethicon Endo-Surgery, Cincinnati, OH) in all cases [18 21]. During anastomosis, a suctiontye mechanical stabilizer (Octous 4.3; Medtronic, Minneaolis, MN) was used to immobilize the target site of the coronary artery. Distal myocardial erfusion was maintained using an intracoronary shunt tube (Anastaflo; Edwards Lifescience, Irvine, CA). Vein-to-aorta roximal anastomosis was erformed using a artial claming or an anastomotic device. To revent comlications related to maniulation of the ascending aorta, we routinely erformed comuted tomograhic scan and eiaortic ultrasonograhy and assessed the severity and location of atherosclerosis of the aorta. When the surgeon judged that artial cluming of the ascending aorta increased the risk of embolism, a roximal anastomotic device including the Novare Enclose device (Novare Surgical Systems, Cuertino, CA), the HEARTSTRING Proximal

3 Ann Thorac Surg KINOSHITA ET AL 2010;90: SKELETONIZED BILATERAL ITA IN DIABETICS 1175 Seal System (Guidant Cororation, Santa Clara, CA), or the Symmetry Aortic Connector System (St. Jude Medical, St. Paul, MN) was used. Graft Arrangement The basic strategy for myocardial revascularization was in situ grafting of an ITA to the left anterior descending coronary artery. The second ITA or a sahenous vein was grafted to circumflex branches or diagonal branches. The inferior wall was revascularized using a sahenous vein or in situ gastroeiloic artery. Use of the gastroeiloic artery required stenosis of greater than 90% of the target vessels. In the majority of atients who received grafting, the in situ right ITA was tunneled through a right ericardial incision and routed anterior to the aorta across the midline for grafting to the left anterior descending coronary artery and the in situ left ITA was used for the diagonal or circumflex branches. To revent comlications related to resternotomy, at the end of the rocedures the right ITA was covered with loosely aroximated mediastinal tissue before the sternum was aroximated with wires. On rare occasions, when the in situ right ITA was too short for grafting to the left anterior descending coronary artery, the in situ right ITA was grafted to the circumflex branches through the transverse sinus and the in situ left ITA was grafted to the left anterior descending coronary artery. When the right ITA was injured at its roximal ortion or was too short for grafting to the left anterior descending coronary artery and circumflex branches, a comosite graft was constructed. In those cases, the in situ left ITA was anastomosed to the left anterior descending coronary artery, the free graft of the right ITA was anastomosed to the in situ left ITA in end-to-side fashion, and its distal end was connected to the circumflex branches. Comlete revascularization was accomlished when at least one byass graft was laced distal to a 75% or greater narrowing in each vessel of diseased territory. Left main trunk stenosis would require byass grafting to both the left anterior descending coronary artery and the circumflex territory to be considered comlete. Statistical Analysis Baseline characteristics, oerative data, ostoerative comlications, and rates of outcomes were comared using Pearson 2 test (categorical variables), Student s t test (continuous variables), and Mann-Whitney U test (continuous, skewed data). The Kalan-Meier method was used for describing 7-year survival, and the log rank test was alied for the comarison. The Cox roortional hazard model was used for estimating hazard ratios and 95% confidence intervals. To identify otential redictors of overall death, cardiac death, and cardiac event, each variable of baseline characteristics and oerative data was entered into univariate analysis. Those redictors were then included in the multivariate Cox model with backward elimination ( 0.05 for retention). The significance level of the robability value was set at less than Statistical analyses were erformed with the SPSS 11.0 (SPSS Inc, Chicago, IL). Results In the original cohort, atients who received grafting had significantly greater number of target vessels and more often had critical stenoses in the left main trunk and circumflex artery (Table 1). After roensity score matching, a total of 31 baseline characteristics were similar for the two matched grous, including coronary anatomy (Table 2). In both grous, all atients underwent Table 2. Baseline Characteristics in Proensity-Matched Pairs a Logistic EuroSCORE 7 (6 9) 7 (5 10) 0.41 Age (y) Female 43 (25.0) 41 (23.9) 0.56 Body mass index (kg/m 2 ) Diabetes mellitus 170 (100) 170 (100) 0.99 HgbA1C (%) Tyes of treatment 0.68 Diet 30 (17.5) 31 (18.0) Oral 56 (32.7) 59 (34.6) Insulin 85 (49.8) 81 (47.4) Chronic kidney disease Nondialysis-deendent 27 (16.0) 25 (14.5) 0.46 Dialysis-deendent 21 (12.1) 21 (12.1) 0.93 Duration (y) Smoking 83 (49.1) 88 (52.0) 0.38 Periheral arterial disease 32 (18.6) 25 (14.8) 0.29 Chronic obstructive ulmonary 35 (20.3) 31 (18.1) 0.64 disease Hyerliidemia 79 (46.7) 84 (49.6) 0.32 Hyertension 126 (74.2) 128 (75.2) 0.76 Previous myocardial infarction 79 (46.7) 74 (43.3) 0.35 History of ercutaneous 48 (28.3) 49 (28.9) 0.87 coronary intervention Emergent oeration 12 (6.8) 8 (4.8) 0.40 Coronary anatomy No. target vessels Left main trunk stenosis 50% 58 (34.4) 64 (37.5) 0.28 Left anterior descending artery 170 (100) 170 (100) % Diagonal branch 75% 70 (41.2) 75 (44.1) 0.41 Circumflex artery 75% 127 (74.7) 128 (75.3) 0.66 Right coronary artery 75% 124 (72.9) 118 (69.4) 0.25 Echocardiograhic findings Ejection fraction (%) Ejection fraction 40% 41 (24.1) 39 (22.9) 0.69 LV diastolic dimension (mm) LV systolic dimension (mm) Left atrial dimension (mm) a Data are number (%) or mean standard deviation, or median (interquartile range). bilateral internal thoracic artery; EuroSCORE Euroean System for Cardiac Oerative Risk Evaluation; HgbA1C main fraction of glycosylated hemoglobin; LV left ventricle; single internal thoracic artery.

4 1176 KINOSHITA ET AL Ann Thorac Surg SKELETONIZED BILATERAL ITA IN DIABETICS 2010;90: myocardial revascularization using the off-um technique without conversion to cardioulmonary byass during oeration. All arterial conduits were harvested with the skeletonization technique. Oerative Data The number of grafts tended to be greater in the grou, but the number of distal anastomoses was similar in the two grous. Sequential grafting was more often used in the grou. The rate of comlete revascularization was similar between the grous (Table 3). Table 4 summarizes ITA arrangements and graft combinations. In both grous, the left anterior descending coronary artery was revascularized using an in situ ITA. In the grou, the second ITA was anastomosed to the circumflex artery or diagonal branch as an in situ graft in 162 atients (95.3%) and as a comosite graft in 8 atients (4.7%). The gastroeiloic artery was used as an in situ graft in 97 atients (57.1%) in the grou and 68 atients (40.0%) in the grou ( 0.01). The sahenous vein was used in 22 atients (12.9%) in the grou and 150 atients (88.2%) in the grou ( 0.01). Of these, artial claming was used in 17 atients (77.3%; 17 of 22) in the grou and 115 atients (76.7%; 115 of 150) in the grou ( 0.57); an anastomotic device was used in 5 atients (22.7%; 5 of 22) in the grou (3 atients used the Enclose, 1 the HEARTSTRING, and 1 the Aortic Connector) and 35 atients (23.3%, 35 of 150) in the grou (18 atients used the Enclose, 8 the HEARTSTRING, and 9 the Aortic Connector). Postoerative Data There was no significant difference between the two grous in the occurrence of ostoerative comlications (Table 5). Blood glucose levels of the versus grou on ostoerative day 0, 1, and 2 were versus mg/dl ( 0.35), versus mg/dl ( 0.33), and versus mg/dl ( 0.26), resectively. Midterm Outcomes and Cox Analysis The collection of long-term outcomes was comlete in 99.3% of atients. Patients were followed u for a mean of 3.2 years (maximum, 7.8 years) after surgery. During this eriod, atients in the grou had fewer rates of overall death, cardiac death, and cardiac event than Table 3. Details of Oerative Procedures a No. grafts No. distal anastomoses Sequential grafting 130 (76.5) 106 (62.4) 0.01 Comlete revascularization 168 (98.8) 170 (100) 0.28 a Data are number (%) or mean standard deviation. Table 4. Internal Thoracic Artery (ITA) Arrangements and Graft Combinations ITA Arrangement Number grou n 170 In situ RITA-LAD, in situ LITA-CX, and/or 151 diagonal branch In situ LITA-LAD, in situ RITA-CX 11 In situ LITA-LAD, in situ LITA-comosite 7 RITA-CX In situ LITA-LAD, in situ LITA-comosite 1 RITA-PDA grou n 170 In situ LITA-LAD 167 In situ RITA-LAD 3 Graft combinations grou n 170 LITA RITA 52 LITA RITA GEA 96 LITA RITA GEA SV 1 LITA RITA SV 21 grou n 170 LITA GEA 18 LITA SV GEA 48 LITA SV 81 LITA SV SV 20 RITA SV 1 RITA GEA 2 bilateral internal thoracic artery; CX circumflex artery; GEA gastroeiloic artery; LAD left anterior descending artery; LITA left internal thoracic artery; PDA osterior descending artery; RITA right internal thoracic artery; single internal thoracic artery; SV sahenous vein. atients in the grou. However, there was no difference in noncardiac deaths between the two grous (Table 6). Survival data are resented in Figures 1, 2, and 3. The 1-, 3-, and 5-year versus grafting survival rates free from overall death were 98.2% versus 94.5 %, 92.0% versus 81.6%, and 87.5% versus 70.8%, resectively (log-rank test 0.01). For freedom from cardiac death, the resective rates were 98.8% versus 95.7%, 95.8% versus 86.6%, and 92.1% versus 78.7% ( 0.01). For freedom from cardiac event, the resective Table 5. Postoerative Comlications a Dee sternal infection 3 (1.8) 4 (2.4) 0.72 Atrial fibrillation 36 (21.2) 30 (17.6) 0.42 Reexloration for bleeding 2 (1.2) 3 (1.8) 0.61 Perioerative myocardial 1 (0.6) 1 (0.6) 0.92 infarction Stroke 3 (1.8) 1 (0.6) day mortality 3 (1.8) 2 (1.2) 0.61 a Data are number (%). bilateral internal thoracic artery; thoracic artery. single internal bilateral internal thoracic artery; thoracic artery. single internal

5 Ann Thorac Surg KINOSHITA ET AL 2010;90: SKELETONIZED BILATERAL ITA IN DIABETICS 1177 Table 6. Rates of Death and Cardiac Event a Overall death 32 (18.8) 14 (8.2) 0.01 Cardiac death 23 (13.5) 8 (4.7) 0.01 Myocardial infarction 9 (5.3) 1 (0.6) 0.02 Heart failure 4 (2.4) 2 (1.2) 0.69 Sudden death 10 (5.8) 5 (2.9) 0.29 Vascular death 3 (1.8) 0 (0) 0.25 Noncardiac death 6 (3.5) 4 (2.4) 0.52 Cardiac event 21 (12.4) 9 (5.3) 0.03 a Data are number (%). bilateral internal thoracic artery; thoracic artery. single internal rates were 100.0% versus 97.5%, 95.6% versus 89.4%, and 91.0% versus 72.6% ( 0.01). In a multivariate Cox model including all otential redictors, grafting was significantly associated with a lower risk for overall death, cardiac death, and cardiac event (Table 7). Comment The major findings of the resent study were that among 340 roensity score-matched atients with diabetes undergoing off-um coronary artery byass graft surgery using skeletonized ITA, the rates of overall death, cardiac death, and cardiac event in the grou were significantly lower than in the grou; grafting was significantly associated with a lower risk for overall death, cardiac death, and cardiac event after adjustment for otential confounders; the rates of noncardiac death and ostoerative comlications were similar between the two grous. Several investigators investigated the survival benefit of grafting in atients with diabetes [11 15]. Lev- Ran and associates [13] reorted sueriority of grafting in terms of survival, freedom from cardiac death, Fig 2. Freedom from cardiac death. ( bilateral internal thoracic artery; single internal thoracic artery.) and major adverse cardiac events in 285 diabetic atients. In this study, the second ITA was anastomosed to the circumflex artery in all atients (68.8% as a comosite graft and 31.2% as an in situ graft). Calafiore and colleagues [14] demonstrated the survival benefit of grafting in 200 roensity score-matched diabetic atients at a mean follow-u of 6.0 years. In this study, the second ITA was anastomosed to the circumflex artery in 86.5% of the grou (173 of 200), used as an in situ graft in 55.0% (110 of 200), and as a Y comosite graft in 45.0% (90 of 200). Toumoulis and colleagues [15] investigated outcomes in 980 roensity-score matched diabetic atients at a mean follow-u of 4.7 years. There was no significant effect of grafting comared with grafting on long-term survival. They reorted no information about ITA arrangement. In our study, the first Fig 1. Freedom from overall death. ( bilateral internal thoracic artery; single internal thoracic artery.) Fig 3. Freedom from cardiac event. ( bilateral internal thoracic artery; single internal thoracic artery.)

6 1178 KINOSHITA ET AL Ann Thorac Surg SKELETONIZED BILATERAL ITA IN DIABETICS 2010;90: Table 7. Multivariate Cox Model for Outcomes Hazard Ratio (95% Confidence Interval) Overall Death a grafting 0.45 ( ) 0.02 Age b 2.08 ( ) 0.01 Dialysis-deendent chronic 3.15 ( ) 0.01 kidney disease Periheral arterial disease 2.33 ( ) 0.02 Previous myocardial infarction 2.13 ( ) 0.01 Ejection fraction 40% 2.78 ( ) 0.01 Cardiac death c grafting 0.43 ( ) 0.02 Dialysis-deendent chronic 2.89 ( ) 0.02 kidney disease Previous myocardial infarction 3.45 ( ) 0.01 Ejection fraction 40% 3.22 ( ) 0.01 Cardiac event d grafting 0.42 ( ) 0.02 Dialysis-deendent chronic 3.02 ( ) 0.02 kidney disease Ejection fraction 40% 3.28 ( ) 0.01 a s included in the model but not found to be indeendent redictors were main fraction of glycosylated hemoglobin (HgbA1C), emergent oeration, chronic obstructive ulmonary disease, functional class III or IV, and left ventricular diastolic dimension. b Hazard ratio er 10-year increase. c s included in the model but not found to be indeendent redictors were age, eriheral arterial disease, and left ventricular diastolic dimension. d s included in the model but not found to be indeendent redictors were eriheral arterial disease, revious myocardial infarction, and left ventricular diastolic dimension. bilateral internal thoracic artery. ITA was anastomosed as an in situ graft to the left anterior descending coronary artery in all atients and the second ITA was anastomosed to the circumflex artery or the diagonal branch as an in situ graft in 162 atients (95.3%; 162 of 170) and as a comosite graft in 8 atients (4.7%; 8 of 170). We believe that grafting rovides better long-term survival in atients with diabetes than grafting when was anastomosed to the left coronary system. In comarison with other studies that demonstrated the survival benefit of grafting [4 10], the resent study had a smaller samle size and shorter duration of follow-u. However, in our study, all atients had diabetes with a mean age of 69 years and median logistic Euroean System for Cardiac Oerative Risk Evaluation of 7(Tables 1, 2). They are regarded as high-risk atients for whom what would be a nonfatal event for low-risk atients can easily cause fatal outcomes. We believe that this is the reason why the survival benefit of the grafting becomes clear during the relatively short follow-u in our study. The grou had more gastroeiloic artery and less sahenous vein used for anastomosis than the grou. The reasons for this can be given as follows. The grou needed at least one graft to revascularize the osterior descending artery in addition to because the was anastomosed to the left coronary system in most cases. The gastroeiloic artery was aggressively used as a third conduit in the grou when the osterior descending artery had greater than 90% stenosis. On the other hand, the gastroeiloic artery was not used in the grou as much as in the grou because a sahenous vein was mainly used as a sequential graft to revascularize both the circumflex branches and the osterior descending artery. Reduction of wound infections in atients with diabetes has been demonstrated in some reorts when was harvested in a skeletonization technique [22, 23]. According to these reorts, the rates of dee sternal infection were 1.8% [22] and 3.5% [23]. Moreover, tight glycemic control with insulin infusion reortedly decreases the incidence of wound comlications [24].Inour study, the ITA was harvested with the skeletonization technique in all atients, and ostoerative serum glucose was well controlled. Dee sternal infection occurred in 4 atients (2.4%) in the grou and 3 atients (1.8%) in the grou ( 0.72). We believe that diabetes is no contraindication to the use of if the skeletonization technique is roerly used and serum glucose is well managed. Selection bias is a major roblem inherent in a nonrandomized study. In the resent study, in an attemt to minimize selection bias, we excluded atients who could not be otential candidates for grafting. Moreover, we created roensity scores based on 12 reoerative factors and then matched 170 atients who underwent grafting to 170 atients who underwent grafting according to that score, resulting in all reoerative baseline characteristics being similar for the two study cohorts. Limitations There are several imortant limitations to this study. First, even with roensity score matching, we cannot truly evaluate the effect of grafting. Although the roensity score can adjust for confounding by indication and selection bias, we cannot eliminate residual confounding caused by unobserved factors. Second, the heterogeneous distribution of gastroeiloic artery and sahenous vein use between the grous also made a fair comarison difficult. Finally, the lack of available coronary angiograhic data did not allow us to evaluate graft atency. Conclusions Off-um skeletonized left-sided grafting is associated with better long-term survival than grafting, without increasing the risk of dee sternal infection in diabetic atients. References 1. Morris JJ, Smith LR, Jones RH, et al. Influence of diabetes and mammary artery grafting on survival after coronary byass. Circulation 1991;84(Sul 3):

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