Diabetes mellitus is an established risk factor for the

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1 Influence of Diabetes on Mortality and Morbidity: Off-Pump Coronary Artery Bypass Grafting Versus Coronary Artery Bypass Grafting With Cardiopulmonary Bypass Mitchell J. Magee, MD, Todd M. Dewey, MD, Tea Acuff, MD, James R. Edgerton, MD, James F. Hebeler, MD, Syma L. Prince, RN, and Michael J. Mack, MD Cardiopulmonary Research Science and Technology Institute, Dallas, Texas Background. Myocardial revascularization in diabetic patients is challenging with no established optimum treatment strategy. We reviewed our coronary artery bypass grafting experience to determine the impact of eliminating cardiopulmonary bypass on outcomes in diabetic patients relative to nondiabetic patients. Methods. From January 1995 through December 1999, 9,965 patients, of whom 2,891 (29%) had diabetes, underwent isolated coronary artery bypass grafting. Diabetic and nondiabetic patients were further divided into groups on the basis of cardiopulmonary bypass use. Twelve percent (346 of 2,891) of diabetic patients and 12% (829 of 7,074) of nondiabetic patients underwent coronary artery bypass grafting without cardiopulmonary bypass; the remainder had coronary artery bypass grafting with cardiopulmonary bypass. Nineteen preoperative variables were compared among treatment groups by univariate analysis. Results. Patients undergoing coronary artery bypass grafting without cardiopulmonary bypass compared with those having coronary artery bypass grafting with cardiopulmonary bypass had higher mean predicted mortalities (diabetic, 3.96% versus 3.72%, p 0.83; nondiabetic, 3.03% versus 2.86%, p 0.79). In nondiabetic patients, coronary artery bypass grafting without cardiopulmonary bypass provides an actual and risk-adjusted survival advantage over coronary artery bypass grafting with cardiopulmonary bypass (1.81% versus 3.44%, p ; risk-adjusted mortality, 1.79% versus 3.61%, p 0.007). This survival benefit of coronary artery bypass grafting without cardiopulmonary bypass was not seen in diabetic patients (2.89% versus 3.69%, p 0.452; risk-adjusted mortality, 2.19% versus 2.98%, p 0.42). Diabetic patients undergoing coronary artery bypass grafting without cardiopulmonary bypass had fewer complications, including decreased blood product use (34.39% versus 58.4%, p 0.001), and reduced incidence of prolonged ventilation (6.94% versus 12.10%, p 0.005), atrial fibrillation (15.90% versus 23.26%, p 0.002), and renal failure requiring dialysis (0.87% versus 2.75%, p 0.036). Conclusions. The survival advantage in nondiabetic patients treated with coronary artery bypass grafting without cardiopulmonary bypass is not apparent in diabetic patients. Coronary artery bypass grafting without cardiopulmonary bypass in diabetic patients is nevertheless associated with a significant reduction in morbidity. (Ann Thorac Surg 2001;72:776 81) 2001 by The Society of Thoracic Surgeons Presented at the Forty-seventh Annual Meeting of the Southern Thoracic Surgical Association, Marco Island, FL, Nov 9 11, Address reprints requests to Dr Magee, 7777 Forest Lane, Suite A323, Dallas, TX 75230; mmagee@csant.com. Diabetes mellitus is an established risk factor for the development of coronary artery disease. Coronary artery disease is not only more prevalent in diabetic patients compared with nondiabetic patients, but also tends to be more extensive, involving multiple vessels, and rapidly progressive [1 6]. Accordingly, diabetic patients represent a large proportion of patients requiring myocardial revascularization. Unfortunately, diabetes is also a significant risk factor for adverse early and late outcomes after percutaneous and surgical revascularization [7 10]. Diabetes is associated with higher restenosis rates after angioplasty and stent placement [11 13]. Although diabetic patients typically do worse with any management approach than nondiabetic patients, studies comparing treatment options in diabetic patients have been conflicting. The Bypass Angioplasty Revascularization Investigation trial reported a survival benefit in diabetic patients treated with coronary artery bypass grafting (CABG) compared with percutaneous transluminal coronary angioplasty, whereas other studies failed to show a significant difference [6, 14 16]. The reported effects of eliminating cardiopulmonary bypass (CPB) on morbidity and mortality in patients undergoing CABG are mostly favorable, although some have been conflicting or inconclusive [17 20]. The greatest benefit derived from eliminating CPB in CABG most likely exists in a selected risk subset of patients [21 24]. With diabetic patients representing a particularly challenging group 2001 by The Society of Thoracic Surgeons /01/$20.00 Published by Elsevier Science Inc PII S (01)

2 Ann Thorac Surg MAGEE ET AL 2001;72: DIABETES AND OFF-PUMP CABG 777 Table 1. Preoperative Risk Factors (346, 12%) Diabetic (2,891, 29%) Nondiabetic (7,074, 71%) (2,545, 88%) p Value (829, 12%) (6,245, 88%) p Value Age (y) a Female 36.42% 30.49% % 21.54% COPD 17.63% 19.72% % 21.75% HTN 73.12% 73.24% % 62.91% RF 9.54% 6.05% % 2.07% RF-Dialysis 4.05% 2.08% % 0.48% Obesity 13.01% 24.4% % 10.41% Arrhythmia 12.14% 13.05% % 14.30% Left main 15.32% 22.04% % 23.75% MI 7 days 14.45% 21.93% % 23.17% USA 32.08% 55.76% % 57.34% a Data are presented as mean standard deviation. coronary artery bypass grafting with cardiopulmonary bypass; COPD chronic obstructive pulmonary disease; HTN hypertension; MI myocardial infarction; coronary artery bypass grafting without cardiopulmonary bypass; RF renal failure; RF-Dialysis renal failure requiring dialysis; USA unstable angina. with no optimum treatment strategy established, the opportunity to improve outcomes with a contemporary therapeutic approach is evident. Therefore, we reviewed our CABG experience to determine the impact of CPB on outcomes in diabetic patients relative to nondiabetic patients. Patients and Methods Patients A retrospective review of prospective data collected in our customized Society of Thoracic Surgeons (STS) computerized cardiac surgery group practice database identified 9,965 patients who underwent isolated CABG from January 1995 through December 1999, of whom 2,891 (29%) were diabetic and 7,074 (73%) were nondiabetic. Twelve percent (346 of 2,891) of diabetic patients and 12% (829 of 7,074) of nondiabetic patients underwent CABG without CPB (off-pump CABG; ). The remaining 88% in each group had conventional CABG using CPB (). Among the total diabetic population, 35.51% were being treated with insulin. Insulin-requiring diabetic patients constituted 39.83% of the diabetic group and 34.93% of the diabetic group. Procedure selection was at the discretion of the operating surgeon and varied accordingly. No specified selection criteria were used in determining which CABG procedure, with or without CPB, individual patients would receive, although medical comorbidities considered to increase the risks of CPB were generally used to select patients for. The and patients were contemporaneous and not sequential cohorts. Patient data were collected and analyzed according to the STS National Cardiac Surgery Database guidelines and definitions ( Preoperative patient data were obtained relative to cerebrovascular disease, chronic obstructive pulmonary disease, cerebrovascular accident, hypertension, morbid obesity, peripheral vascular disease, renal failure, renal failure on dialysis, sex, current smoking, unstable angina, recent myocardial infarction (MI), arrhythmias, congestive heart failure, left main coronary artery disease, New York Heart Association class IV classification, age, and left ventricular ejection fraction. Postoperative data collected and compared between groups included length of hospital stay from operation to discharge, operative mortality, blood product use, reoperation for bleeding, MI, adult respiratory distress syndrome, prolonged ventilation, renal failure, renal failure requiring dialysis, transient and permanent neurologic dysfunction, infection, and atrial fibrillation. Statistical Analysis Patients were grouped and compared according to preoperative disease status, diabetic versus nondiabetic, and according to surgical treatment, versus CABG- CPB. Preoperative patient characteristics, intraoperative course, and operative outcomes were collected and compared among groups using either the 2 test or two-tailed Student s t test as appropriate. Probability values less than or equal to 0.05 were considered significant. The predicted risk of operative mortality was calculated for each patient using the STS algorithm, and mean predicted risk scores were calculated for each group for comparison. Results Preoperative characteristics that were collected and compared among treatment groups and found to be statistically significant for either diabetic patients or nondiabetic patients are shown in Table 1. The diabetic OPCAB patients as a group were older, more often female, and more likely to have renal failure and renal failure requir-

3 778 MAGEE ET AL Ann Thorac Surg DIABETES AND OFF-PUMP CABG 2001;72: Table 2. Additional Preoperative Risk Factors (346, 12%) Diabetic (2,891, 29%) Nondiabetic (7,074, 71%) (2,545, 88%) p Value (829, 12%) (6,245, 88%) p Value LVEF a CVD 12.72% 13.91% % 9.96% Prior CVA 9.25% 8.61% % 4.26% PVD 16.18% 17.29% % 11.48% Current smoker 21.68% 18.78% % 25.96% CHF 20.23% 19.41% % 10.57% NYHA IV 80.92% 82.67% % 80.98% a Data are presented as mean standard deviation. coronary artery bypass grafting with cardiopulmonary bypass; CHF congestive heart failure; CVA cerebrovascular accident; CVD cerebrovascular disease; LVEF left ventricular ejection fraction; NYHA New York Heart Association; coronary artery bypass grafting without cardiopulmonary bypass; PVD peripheral vascular disease. ing dialysis when compared with diabetic patients. Likewise, the nondiabetic OPCAB patients were older, more often female, and more likely to have renal failure and renal failure requiring dialysis when compared with nondiabetic patients. In contrast, obesity, left main coronary artery disease, recent MI, and unstable angina were more prevalent in the diabetic group compared with their OPCAB cohort. Likewise, obesity, left main coronary artery disease, recent MI, and unstable angina as well as hypertension, lung disease, and arrhythmias were more prevalent in the nondiabetic group compared with their OPCAB cohort. Additional risk factors examined and found to be similar among treatment groups are shown in Table 2. Most notable were the similarities in ventricular function, heart failure, and cerebrovascular disease. In an effort to clarify and better define differences in risk between the two obviously disparate versus treatment groups, the STS-predicted risk of mortality was calculated for each patient, and the means were compared for both diabetic patients and nondiabetic patients. The group had a higher predicted risk for mortality than the group in both diabetic and nondiabetic patients, albeit not statistically significant as determined by the STS algorithm. The unadjusted and risk-adjusted mean operative mortality was less in the group compared with the group. This survival benefit of was highly significant in the nondiabetic patients (Table 3). The groups demonstrated fewer complications. The incidences of prolonged ventilation and blood product use were significantly less in both diabetic and nondiabetic patients compared with CABG- CPB patients. The incidences of postoperative adult respiratory distress syndrome and perioperative MI were significantly decreased in the nondiabetic patients. A favorable impact of on postoperative length of hospital stay was seen in diabetic and nondiabetic patients, although this was only statistically significant in nondiabetic patients. Benefits of unique to the diabetic population included decreased frequency of postoperative atrial fibrillation and renal failure requiring dialysis (Table 4). Postoperative complications that occurred with similar frequency in diabetic and nondiabetic treatment groups are shown in Table 5. Comment Patients selected for in this study had a higher predicted risk for mortality than those selected for, yet the observed mortality was less. The patients not only had decreased observed and risk-adjusted mortality but also decreased morbidity. The benefits of were significantly greater in the nondiabetic population. This retrospective review of prospectively collected data represents 22 cardiac surgeons in multiple hospitals with a wide variety of experience with techniques and rates of incorporation of OPCAB into individual practice. Accordingly, various and diverse selection criteria for the chosen surgical approach were applied in this nonrandomized comparison. This lack of randomization is a limitation to drawing definitive conclusions from this study. Patients were initially selected for on the basis of suitable Table 3. Mean Observed and Predicted Mortality Treatment Group Diabetic Nondiabetic Predicted Observed RAM Predicted Observed RAM 3.96% 2.89% 2.19% 3.03% 1.81% 1.79% 3.72% 3.69% 2.98% 2.86% 3.44% 3.61% p Value coronary artery bypass grafting with cardiopulmonary bypass; bypass; RAM risk-adjusted mortality. coronary artery bypass grafting without cardiopulmonary

4 Ann Thorac Surg MAGEE ET AL 2001;72: DIABETES AND OFF-PUMP CABG 779 Table 4. Significant Postoperative Complications and Outcomes Diabetic Nondiabetic p Value p Value LOS a ARDS 0.58% 1.14% % 1.78% MI 1.16% 1.61% % 1.97% Atrial fibrillation 15.90% 23.26% % 22.59% RF-Dialysis 0.87% 2.75% % 1.28% Prolonged ventilation 6.94% 12.10% % 9.45% Blood use 34.39% 58.47% % 54.27% a Days in hospital from operation to hospital discharge. Data are presented as mean standard deviation. ARDS adult respiratory distress syndrome; coronary artery bypass grafting with cardiopulmonary bypass; LOS length of stay; MI myocardial infarction; coronary artery bypass grafting without cardiopulmonary bypass; RF-Dialysis renal failure requiring dialysis. coronary anatomy as well as individual patient characteristics believed to increase their CPB-associated risks, such as advanced age, cerebrovascular accident, renal disease, or chronic obstructive pulmonary disease. In general, selection criteria broadened with experience. During the period of study, diabetic patients as a group selected for were older, more often female, and with renal impairment in accordance with higher risk status, but less often obese and less likely to have left main coronary artery disease, recent MI, or unstable angina. These differences in risk factors trended toward a higher overall mean predicted risk for the group, although statistically the groups were similar. In nondiabetic patients, identical disparities noted above existed between therapeutic groups, with the addition of less hypertension, chronic obstructive pulmonary disease, and preoperative arrhythmias in the group. Again these differences yielded a higher mean predicted risk score in the group although the groups were statistically identical. This study did not exclude single-vessel disease. Both diabetic and nondiabetic groups had a lower mean number of grafts per patient than their cohorts (diabetic, 2.3 versus 3.5; nondiabetic, 2.2 versus 3.4, respectively). This is largely a reflection of a much higher proportion of single CABG procedures in the groups (diabetic, versus 0.014; nondiabetic, versus 0.028). The similarity in predicted risk scores among treatment groups, trending toward a higher risk in the groups, argues against this having a favorable impact on outcomes. Fewer mean grafts per patient may reflect an selection bias for patients who require fewer grafts. Alternatively, surgeons performing may have a surgeon-specific propensity to perform fewer grafts independent of the selected approach or may be influenced by procedure-related technical challenges to perform fewer grafts. The limitations of this database do not allow for precise anatomic characterization of preoperative coronary artery disease and the corresponding grafts required to achieve complete revascularization. Therefore, no conclusions can be drawn from this data as to the relative completeness of revascularization among groups. Nondiabetic patients clearly derive a significant benefit from an approach reflected in decreased unadjusted and risk-adjusted mortality as well as decreased morbidity, including decreased blood product use, decreased incidence of adult respiratory distress syndrome and prolonged ventilation, and decreased postoperative hospital length of stay. It is unclear why diabetic patients do not derive the same benefits from as nondiabetic patients. There may be factors with higher prevalence in the diabetic population, such as diffuse small vessel coronary artery disease, renal insufficiency, peripheral vascular disease, or other confounding risk variables that affect these findings. The diabetic treatment groups are smaller Table 5. Nonsignificant Postoperative Complications and Outcomes Diabetic Nondiabetic p Value p Value Stroke permanent 0.87% 1.22% % 0.77% Stroke transient 0.87% 1.49% % 0.98% Reop bleed 1.45% 3.22% % 3.55% Reop gft occl 0.29% 0.08% % 0.19% Renal failure 4.62% 5.89% % 2.85% Wound infection 4.34% 4.05% % 3.04% coronary artery bypass grafting with cardiopulmonary bypass; coronary artery bypass grafting without cardiopulmonary bypass; Reop bleed reoperation for bleeding; Reop gft occl reoperation for graft occlusion.

5 780 MAGEE ET AL Ann Thorac Surg DIABETES AND OFF-PUMP CABG 2001;72: than the nondiabetic groups and may simply not be large enough to reflect a survival benefit. Narrowing the analysis to include only treated diabetic patients, either with oral medication or insulin, or further narrowing the comparison to include only insulin-treated diabetic patients resulted in conclusions similar to those drawn from the entire diabetic population. Likewise, adjusting for differences in risk between diabetic treatment groups by comparing mean risk-adjusted mortalities did not alter the conclusion. Diabetic patients as a group, compared with, do benefit from less blood product use, less incidence of prolonged ventilation, less incidence of postoperative renal failure requiring dialysis, and less postoperative atrial fibrillation. This was reflected in a trend toward a decreased postoperative length of hospital stay. In conclusion, provides a significant survival advantage in nondiabetic patients. Off-pump CABG in diabetic patients and nondiabetic patients is associated with a significant reduction in morbidity. Additional studies including larger numbers of diabetic patients or prospective randomization are needed to confirm these conclusions. References 1. Krolewski AJ, Kosinski EJ, Warram JH, et al. Magnitude and determinants of coronary artery disease in juvenile-onset, insulin-dependent diabetes mellitus. Am J Cardiol 1987;59: Hamby RI, Sherman L, Mehta J, Aintablain A. Reappraisal of the role of the diabetic state in coronary artery disease. Chest 1976;70: Nathan DM. Long-term complications of diabetes mellitus. N Engl J Med 1993;328: Barbash GI, White HD, Modan M, Van de Werf F. Significance of diabetes mellitus in patients with acute myocardial infarction receiving thrombolytic therapy: investigators of the International Tissue Plasminogen Activator/Streptokinase Mortality Trial. J Am Coll Cardiol 1993;22: Jacoby RM, Nesto RW. Acute myocardial infarction in the diabetic patient: pathophysiology, clinical course and prognosis. J Am Coll Cardiol 1992;20: Gum PA, O Keefe JH Jr, Borkon AM, et al. Bypass surgery versus coronary angioplasty for revascularization of treated diabetic patients. Circulation 1997;96(Suppl 2):II Kip KE, Faxon DP, Detre KM, Yeh W, Kelsey SF, Currier JW. Coronary angioplasty in diabetic patients: the National Heart, Lung and Blood Institute Percutaneous Transluminal Coronary Angioplasty Registry. Circulation 1996;94: Barsness GW, Peterson ED, Ohman EM, et al. Relationship between diabetes mellitus and long-term survival after coronary bypass and angioplasty. Circulation 1997;96: Stein B, Weintraub WS, Gebhart SP, et al. Influence of diabetes mellitus on early and late outcome after percutaneous trans-luminal coronary angioplasty. Circulation 1995; 91: Cohen Y, Raz I, Merin G, Mozes B. Comparison of factors associated with 30-day mortality after coronary artery bypass grafting in patients with versus without diabetes mellitus. Am J Cardiol 1998;81: Carrozza JP Jr, Kuntz RE, Fishman RF, Baim DS. Restenosis after arterial injury caused by coronary stenting in patients with diabetes mellitus. Ann Intern Med 1993;118: Aronson D, Bloomgarden Z, Rayfield EJ. Potential mechanisms promoting restenosis in diabetic patients. J Am Coll Cardiol 1996;27: Kuntz RE. Importance of considering atherosclerosis progression when choosing a coronary revascularization strategy: the diabetes-percutaneous transluminal coronary angioplasty dilemma. Circulation 1999;99: The Bypass Angioplasty Revascularization Investigation (BARI) Investigators. Comparison of coronary bypass surgery with angioplasty in patients with multivessel disease. N Engl J Med 1996;335: Brooks MM, Jones RH, Bach RG, et al. Predictors of mortality and mortality from cardiac causes in the Bypass Angioplasty Revascularization Investigation (BARI) randomized trial and registry. Circulation 2000;101: King SB III, Lembo NJ, Weintraub WS, et al. A randomized trial comparing coronary angioplasty with coronary bypass surgery. Emory Angioplasty versus Surgery Trial (EAST). N Engl J Med 1994;331: Arom KV, Flavin TF, Emery RW, Kshettry VR, Janey PA, Peterson RJ. Safety and efficacy of off-pump coronary artery bypass grafting. Ann Thorac Surg 2000;69: Taggart DP. Respiratory dysfunction after cardiac surgery: effects of avoiding cardiopulmonary bypass and the use of bilateral internal mammary arteries. Eur J Cardiothorac Surg 2000;18: Buffolo E, De Andrade CS, Branco JN, Teles CA, Aguiar LF, Gomes WJ. Coronary artery bypass grafting without cardiopulmonary bypass. Ann Thorac Surg 1996;61: Taggart DP, Browne SM, Halligan PW, Wade DT. Is cardiopulmonary bypass still the cause of cognitive dysfunction after cardiac operations? J Thorac Cardiovasc Surg 1999;118: Arom KV, Flavin TF, Emery RW, Kshettry VR, Peterson RJ, Janey PA. Is low ejection fraction safe for off pump coronary bypass operation? Ann Thorac Surg 2000;70: Trehan N, Mishra YK, Malhotra R, Sharma KK, Mehta Y, Shrivastava S. Off-pump redo coronary artery bypass grafting. Ann Thorac Surg 2000;70: Stamou SC, Dangas G, Dullum M, et al. Beating heart surgery in octogenarians: perioperative outcome and comparison with younger age groups. Ann Thorac Surg 2000;69: Koutlas TC, Elbeery JR, Williams JM, Moran JF, Francalancia NA, Chitwood WR. Myocardial revascularization in the elderly using beating heart coronary artery bypass surgery. Ann Thorac Surg 2000;69: DISCUSSION DR JOSEPH C. CLEVELAND (Denver, CO): Doctor Magee, that was beautifully presented and a nice set of data. It is always even nicer when it correlates with our data. We, similar to you, found that there were more diabetics in our on-pump group that were done, and the risk factors that you displayed are almost similar to those we showed earlier this week. In addition, we have gone through our VA database with Dr Grover and have looked at the risk factors that are prevalent in the diabetic population. There are more women, more patients with renal failure requiring dialysis, et cetera, and these subsets have more comorbidities. I only have one question for you, and that is whether you subgrouped your diabetics into those patients on oral agents versus insulin agents? Historically there are some data that suggest that patients on oral agents do less well with myocardial type events, both with myocardial infarction and with operation. Our laboratory published data some years ago at the basic

6 Ann Thorac Surg MAGEE ET AL 2001;72: DIABETES AND OFF-PUMP CABG 781 science level describing differences in the way human cardiac muscle behaves in oral-dependent diabetics versus insulindependent diabetics. We subsequently learned that the oral agents worked by inhibiting the potassium ATP channel, which is thought to be an endogenous cardiac protector. If there is a difference between the group that was taking oral agents versus insulin agents, it could be the oral group that could be responsible for your lack of benefit. Otherwise I think this is a beautifully presented talk and very relevant, solid data. DR MAGEE: Thank you for your comments. We did in fact look at the insulin dependence of the patients, and you can see, as it is broken down in this slide, that the total number of insulin-dependent patients was 35% of the total population. That represented about 40% of the off-pump group and about 35% of the on-pump group, which was not statistically significant. In looking at morbidity and mortality differences, it did not differ at all from the total population. INVITED COMMENTARY This article by Magee and associates is a study aimed at evaluating the impact of a coronary revascularization using off-pump and traditional cardiopulmonary bypass techniques in both diabetic and nondiabetic patients. This study is a nonrandomized retrospective analysis of 9,965 patients having cardiopulmonary bypass by 22 cardiac surgeons over a 5-year period. This study is timely as the most recent literature demonstrates coronary artery bypass surgery is the preferred method of revascularization in diabetic patients as compared to angioplasty and stent placement; and attempts to provide answers regarding both populations and their preferred surgical treatment. The univariant analysis of diabetics and nondiabetics undergoing coronary surgery concludes that there is a survival advantage in nondiabetics treated with off-pump techniques which is not apparent in the diabetic population. Further it agrees with other studies of off-pump surgery showing fewer blood transfusions, decreased incidence of atrial fibrillation, decreased duration of postoperative ventilation and decreased length of stay. Although the study presents significant data analyzing both techniques and study populations, the reader is left with some confusion as to which technique is best for which population. Most importantly, the study represents two groups with differing risk factors operated upon by multiple surgeons over a 5-year period. It is unclear whether the year of operation, the surgeon doing the surgery, or the technique utilized is the more important factor. The comparison of the four study groups is both confusing and complex with the off-pump group having fewer grafts, better ventricular function and more elective operations. The study is unfortunately subject to the bias of 22 operating surgeons with different selection criteria and operative mortalities. Thus although the paper attempts to provide answers regarding off-pump versus traditional cardiopulmonary bypass surgery in the diabetic and nondiabetic population it falls short of providing us with the answers necessary. Length of stay may be a function of patients operated upon more recently versus the technique utilized. Extubation time likewise may be subject to recent improvements in fast track techniques versus the use of off-pump or traditional cardiopulmonary bypass. Clearly, off-pump techniques are being utilized more frequently in all medical centers throughout the country, and it remains the responsibility of cardiothoracic surgeons to utilize the most effective techniques in a wide range of patients to insure the lowest mortality and morbidity. Further studies in a prospective fashion using better population analysis should provide these answers. George L. Hicks, Jr, MD Division of Cardiothoracic Surgery University of Rochester Medical Center 601 Elmwood Ave Rochester, NY by The Society of Thoracic Surgeons /01/$20.00 Published by Elsevier Science Inc PII S (01)