Renal function following CABG: On-pump vs off-pump

Background Despite the success of on-pump coronary artery bypass grafting (CABG), potential risk of renal dysfunction (RD) related to cardio pulmonary bypass (CPB) is well documented. Recently, several studies have demonstrated that off-pump CABG can be performed safely with results similar to on-pump CABG. Hence renal function in two groups was evaluated to aid in assessment and prevention of acute RD. Methods Study group consisted of 60 patients (30 on-pump, mean age 51.9±8.9 years and 30 off-pump, mean age 56.3±10.1 years) who underwent elective primary CABG. Blood samples were collected pre-operatively and at 6, 24 and 48 hours post-operatively for estimation of serum creatinine and thereby assessment of creatinine clearance. Results 46.66% and 20% of patients developed RD in on-pump and off-pump CABG respectively. Creatinine clearance decreased from a pre-operative value of 81±19.7 ml/min to a postoperative (24hours) value of 72.9±20.5 ml/min in off-pump and from preoperative value of 78.8±24.3 ml/min to a postoperative (24 hours) value of 62.7±18.2 ml/min in on-pump. Creatinine clearance remained significantly depressed for 48 hours in on-pump group where as it was well preserved in the off-pump patients. Decrease in creatinine clearance in on-pump group was significant at 24 hours post-operatively (p=0.045), thus suggesting that renal function was impaired in on-pump group. Hypertension, diabetes and ejection fraction <40% have not influenced significantly in developing RD during on-pump or off-pump CABG. We also found that there was a negative correlation of creatinine clearance with age suggesting that increased age proves to be a risk factor for developing RD in on-pump group. Conclusions Renal function is better preserved in patients undergoing off-pump CABG than on-pump CABG. Increased age proves to be a risk factor for patients undergoing on-pump CABG and hence elderly people have to be preferably allocated to off-pump than on-pump CABG.     

Acute renal failure in coronary artery bypass surgery: independent effect of cardiopulmonary bypass

BACKGROUND: Acute renal failure after cardiac surgery is associated with a high morbidity and mortality, particularly when associated with hemodialysis. The aim of the study was to investigate whether the use of cardiopulmonary bypass increased the risk of developing acute renal failure. METHODS: The 2199 consecutive patients undergoing isolated coronary artery bypass grafting between January 2000 and March 2002 were retrospectively analyzed. Patients with significant preoperative renal dysfunction (preoperative serum creatinine > 200 micromol/L) were excluded. A multivariate logistic regression model was constructed to identify independent risk factors for the development of acute renal failure. RESULTS: In the study, 53 patients (2.4%) developed acute renal failure before hospital discharge. The crude incidences of acute renal failure for isolated coronary artery bypass grafting in the on- and off- pump groups were 2.9% and 1.4%, respectively (p = 0.031). There were 1483 patients who underwent on-pump surgery whereas 716 patients were in the off-pump group. The two groups were broadly comparable on many variables. The off-pump group were slightly younger on average (63.6 versus 64.9 years old [p = 0.017]), but had more angina class IV patients (39.5% versus 28.9% [p < 0.001]) and a greater proportion of redo surgery (4.1% versus 1.6% [p < 0.001]). The on-pump group had more patients with three-vessel disease (82.8% versus 74.3% [p < 0.001]). The logistic regression model identified use of cardiopulmonary bypass as an independent risk factor for the development of acute renal failure (odds ratio 2.64 [95% confidence intervals 1.27 to 5.45]). Other independent predictors of acute renal failure were preoperative creatinine levels, diabetes, emergency operations, increasing age, increasing body mass index, and peripheral vascular disease. CONCLUSIONS: Cardiopulmonary bypass is associated with significantly increased risk of acute renal failure following isolated coronary artery bypass surgery.     

Evaluation of the effectiveness of off-pump coronary artery bypass grafting in high-risk patients: an observational study

Background. Coronary artery bypass grafting in high-risk patients carries substantial morbidity. We compared the effectiveness of off-pump revascularization with that of conventional coronary artery bypass grafting using cardiopulmonary bypass and cardioplegic arrest in consecutive high-risk patients.

Methods. From April 1996 to December 2000, clinical data for consecutive patients undergoing coronary artery revascularization were prospectively entered into a database. Data were extracted for all patients considered to be high risk, defined as the presence of one or more of ten adverse prognostic factors. Hospital mortality and early morbidity were compared between two groups of patients, the on-pump and off-pump groups.

Results. The study group comprised 1,570 consecutive high-risk patients, 332 (21.1%) of whom underwent an off-pump operation. Patients in the on-pump group had fewer high-risk factors and lower Parsonnet scores and were less likely to be 75 years of age or older, to have peripheral vascular disease or hypercholesterolemia, or to have sustained a previous transient ischemic attack. However, they were more likely to be assigned to a higher Canadian Cardiovascular Society class and had more extensive coronary artery disease and were more likely to have unstable angina, to require urgent or emergency operations, and to receive more grafts than those undergoing off-pump procedures. Unadjusted odds ratios for intensive care unit or high-dependency unit stay, total length of stay, blood loss of more than 1,000 mL, postoperative hemoglobin and transfusion requirement all showed a highly significant benefit for the off-pump group (p ≤ 0.005; odds ratios, 0.33 to 0.65). After adjustment for prognostic variables, odds ratios remained essentially unaltered (adjusted odds ratio estimates 0.36 to p < 0.05) except for blood loss of more than 1,000 mL (adjusted odds ratio estimate, 0.82; p = 0.22). Sensitivity analyses confirmed the robustness of these findings.

Conclusions. Off-pump coronary artery bypass grafting is safe, effective, and associated with reduced morbidity in high-risk patients compared with conventional coronary artery revascularization.     

Economic outcome of off-pump coronary artery bypass surgery: a prospective randomized study

Background. Emphasis on cost containment in coronary artery bypass surgery is becoming increasingly important in modern hospital management. The revival of interest in off-pump (beating heart) coronary artery bypass surgery may influence the economic outcome. This study examines these effects.

Methods. Two hundred patients undergoing first-time coronary artery bypass surgery were prospectively randomized to either conventional cardiopulmonary bypass and cardioplegic arrest or off-pump surgery. Variable and fixed direct costs were obtained for each group during operative and postoperative care. The data were analyzed using parametric methods.

Results. There was no difference between the groups with respect to pre- and intraoperative patient variables. Off-pump surgery was significantly less costly than conventional on-pump surgery with respect to operating materials, bed occupancy, and transfusion requirements (total mean cost per patient: on pump, $3,731.6 ± 1,169.7 vs off-pump, $2,615.13 ± 953.6; p < 0.001). Morbidity was significantly higher in the on-pump group, which was reflected in an increased cost.

Conclusions. Off-pump revascularization offers a safe, cost-effective alternative to conventional coronary revascularization with cardiopulmonary bypass and cardioplegic arrest.     

Off-pump coronary artery bypass grafting for elderly patients

Background. The use of off-pump coronary artery bypass grafting (CABG) has recently become widespread, and it has been proven to be less invasive and to facilitate early recovery. In this study, we investigated the efficacy of off-pump CABG for patients aged 75 years or more.

Methods. A retrospective chart review was carried out for patients who underwent isolated off-pump and on-pump CABG at Shin-Tokyo Hospital between January 1997 and December 2000. The patients’ demographic, operative data, and postoperative results were collected.

Results. The off-pump group consisted of 60 men and 44 women with a mean age of 78.8 years, and the on-pump group consisted of 54 men and 20 women with a mean age of 77.6 years. Distal anastomoses were significantly fewer in the off-pump group (2.4 in off-pump group versus 3.7 in on-pump group), but total arterial bypass was more frequently achieved in off-pump group (82.7% versus 25.7%). Intubation time (8.4 versus 18.4 hours), intensive care unit stay (2.2 versus 3.5 days), and postoperative stay (13.8 versus 20.0 days) were significantly shorter in the off-pump group than in the on-pump group (p < 0.05). The frequency of the occurrence of major complications was significantly lower in the off-pump group than the on-pump group, especially in regard to postoperative stroke and respiratory failure (p < 0.05). Multivariate analysis showed that off-pump CABG significantly reduced patient recovery period and the incidence of postoperative complications. Early follow-up results, cardiac event-free and survival rates, did not significantly differ between the two groups.

Conclusions. Off-pump CABG is safe for the elderly patient. Off-pump CABG successfully facilitates early recovery and reduces the incidence of postoperative complications among elderly patients.     

Early and midterm clinical outcome in patients with severe left ventricular dysfunction undergoing coronary artery surgery

BACKGROUND: Patients presenting with severe left ventricular (LV) dysfunction undergoing coronary artery surgery are at increased risk of perioperative morbidity and mortality. The present study investigated early and midterm outcomes in a consecutive series of patients with severe LV dysfunction undergoing coronary surgery at our institution. METHODS: Data on 5,195 consecutive patients undergoing coronary artery bypass grafting (CABG) alone (in-hospital mortality 1.35%) from April 1996 to August 2002 were prospectively recorded in the Patient Analysis and Tracking System. Two hundred and fifty patients (median age 65 years [interquartile range, 57 to 70]) with preoperative left ventricular ejection fraction less than 30% (74 off pump; 29.6%) were identified and early and midterm clinical outcomes analyzed. Propensity scores were used to take account of the imbalance in the distribution of prognostic factors between the on-pump and off-pump groups. RESULTS: Patients undergoing on-pump surgery were less likely to have current congestive heart failure, insulin-dependent diabetes, a history of hypertension, have had gastrointestinal tract surgery or an ulcer, or unstable angina. They had on average lower Parsonnet scores and New York Heart Association and Canadian Cardiovascular Score ratings. However they were more likely to have more extensive coronary artery heart disease and to require more grafts than those undergoing off-pump surgery. After adjustment for consultant team and propensity scores no differences between groups with regard to in-hospital mortality and morbidity were found. The only in-hospital outcome to show a significant difference after adjustment was the need for intraoperative inotropic support, which was higher in the on-pump group (odds ratio 5.1; 95% confidence interval 2.55 to 10.2; p < 0.001)). The median follow-up times for the on- and off-pump groups were 3.4 years and 1.4 years respectively. Three-year survival was higher with on-pump surgery (87% on-pump versus 73% off-pump) but this difference did not reach statistical significance after adjustment for prognostic variables (hazard ratio 0.54, 95% confidence interval 0.22 to 1.26, p = 0.16). CONCLUSIONS: In-hospital mortality and morbidity in patients presenting with severe LV dysfunction is low with comparable results with both on- and off-pump coronary artery surgery. Midterm clinical outcome is encouraging and seems to justify surgical revascularization for this high-risk group of patients.     

Myocardial revascularization with and without cardiopulmonary bypass: advantages, disadvantages and similarities

Objectives: Off-pump coronary artery bypass surgery is becoming increasingly popular although its effectiveness remains controversial. Our goal was to investigate the effectiveness of on-pump and off-pump coronary artery bypass surgery on early (30 days) and long-term (5 years) clinical outcome in two groups of patients selected using propensity scores. Methods: From November 1994 to December 2001, 4381 patients underwent isolated coronary surgery. Applying propensity score matching, 1922 patients were selected (off-pump n=961, on-pump n=961). Results: Stepwise logistic regression analysis showed that the use of cardiopulmonary bypass was an independent predictor for early death, cerebral vascular accident, early negative primary endpoints (ENPEP), and early major events (EME). Five years freedom from both events was similar in the two groups. However, freedom from acute myocardial infarction (AMI) in grafted areas was higher in the off-pump than in the on-pump patients, a possible explanation being the lower postoperative creatine kinase myocardial band (CKMB) release. Grouping all patients according to CKMB peak release also showed that patients with normal release values had higher freedom from all cardiac events investigated. A subgroup analysis of 59 patients converted from off-pump to on-pump showed higher early mortality, ENPEP, and EME. Conversion, however, did not affect late clinical outcome. Conclusions: These results suggest that off-pump surgery reduces early mortality and morbidity. Conversion to on-pump carries high in-hospital mortality and morbidity. Long-term clinical outcome is similar in the two groups; however, off-pump patients seemed to have a higher freedom from AMI in the grafted area which might be related to the lower CKMB peak release when compared with patients undergoing on-pump surgery.     

Prophylactic dialysis in patients with renal dysfunction undergoing on-pump coronary artery bypass surgery

BACKGROUND: Preoperative creatinine values higher than 2.5 mg/dL are associated with markedly increased risk for both mortality and morbidity in patients undergoing coronary artery bypass surgery. We aimed to determine the effects of prophylactic perioperative hemodialysis on operative outcome in patients with nondialysis-dependent moderate renal dysfunction. METHODS: Forty-four adult patients with creatinine levels greater than 2.5 mg/dL but not requiring dialysis underwent coronary artery bypass surgery with cardiopulmonary bypass. The patients were randomly divided into two groups. In group 1 (dialysis group, 21 patients), perioperative prophylactic hemodialysis was performed in all patients. Group 2 (23 patients) was taken as a control group and hemodialysis was performed only if postoperative acute renal failure was diagnosed. RESULTS: The hospital mortality was 4.8% (1 patient) in the dialysis group, and 30.4% (7 patients) in the control group (p = 0.048). Postoperative acute renal failure requiring hemodialysis was seen in 1 patient (4.8%) in the dialysis group and in 8 patients (34.8%) in the control group (p = 0.023). Thirty-three postoperative complications were observed in the control group for an early morbidity of 52.2% (12 patients) and 13 complications occurred in 8 patients in the dialysis group (38.1%). The average length of the intensive care unit and postoperative hospital stay were shorter in the dialysis group than in the control group (p = 0.005 and p = 0.023, respectively). CONCLUSIONS: Preoperative creatinine levels higher than 2.5 mg/dL, increase the risk of mortality and the development of acute renal failure and prolong the length of hospital stay after on-pump coronary artery bypass surgery. Perioperative prophylactic hemodialysis decreases both operative mortality and morbidity in these high-risk patients.     

Acute renal failure in patients with pre-existing renal dysfunction following coronary artery bypass grafting

BACKGROUND: Pre-existing renal dysfunction predisposes to acute renal failure (ARF) in patients undergoing coronary artery bypass grafting. We assessed the incidence and impact of the development of ARF in this patient population in our unit. METHODS: One-hundred and six patients had a preoperative serum creatinine of >or=0.13 mmol/L and underwent coronary artery bypass grafting in the year 2000. The incidence of ARF (as defined by a >or=50% rise in postoperative serum creatinine), hospitalization days, dialysis requirement, in-hospital and 1-year mortality, and potential risk factors for ARF were recorded. RESULTS: Of the patients recorded, 43/104 (41.35%) developed ARF following coronary artery bypass grafting. Patients with ARF stayed in hospital longer (P < 0.02). Ten out of forty-three patients required some form of dialysis and the in-hospital mortality of the renal failure group was 23% compared to 3.1% in the other group (P < 0.002). One year postoperatively, the group with renal failure had significantly worse survival (71.8% vs 98%P < 0.0001). CONCLUSION: For patients undergoing coronary artery bypass grafting, pre-existing renal dysfunction predisposes to the development of ARF, this is associated with prolonged hospitalization and increased mortality.     

Coronary bypass procedures in patients with renal artery stenosis

BACKGROUND AND AIM OF THE STUDY: We present our experience on patients with renal artery stenosis undergoing myocardial revascularization procedures. METHODS: Eighteen patients with varying degrees of renal artery stenosis were operated for coronary artery bypass grafting between 1996 and 2003. The overall incidence was 0.15%. There were nine male and nine female patients with a mean age of 62 +/- 8.2 (40-72 years). Four had bilateral and eight had significant unilateral (>50%) renal artery stenoses. Preoperatively, three patients had renal arterial intervention (stenting), and one patient was on hemodialysis. The mean preoperative creatinine value was 2.6 +/- 2.7 mg/dL (range 0.7 to 9.3). The patients were followed medically: two patients underwent off-pump coronary bypass grafting and the others were operated on-pump. RESULTS: There was only one mortality and two patients required hemodialysis postoperatively. The postoperative mean creatinine values were 3.4 +/- 4.9 mg/dL (range 1.0 to 12.5). No electrolyte imbalances were noted except that one case revealed a transient metabolic acidosis. Five patients required inotropic support with dopamine and two needed diuretic infusions. Only five patients demonstrated a refractory hyper tensive period postoperatively. CONCLUSIONS: The concomitant correction of renal artery stenosis with CABG is usually not necessary, but the principles for renovascular diseases must be kept in mind and individually oriented strategies must be planned.     

Effects of off-pump versus on-pump coronary artery bypass grafting on function and viability of circulating endothelial progenitor cells

OBJECTIVE: Off-pump coronary artery bypass grafting may result in fewer myocardial and vascular complications than on-pump. Although differences in aortic manipulations likely play a role, the systemic responses of endothelial progenitor cells to both types of operations have not been examined. We sought to examine endothelial progenitor cell characteristics after off-pump versus on-pump coronary artery bypass grafting. METHODS: Twenty patients undergoing off-pump or on-pump coronary artery bypass grafting were prospectively enrolled and had endothelial progenitor cells isolated and cultured from their peripheral blood before and 24 hours after surgery. Endothelial progenitor cells were identified by fluorescent dual lectin/low-density lipoprotein binding. Their number, phenotype characteristics, proliferation, migratory function, and viability were determined in a blinded fashion. RESULTS: Patient characteristics and numbers of grafts were equivalent. Endothelial progenitor cells had similar phenotypes between groups before and after surgery. Off-pump and on-pump coronary artery bypass grafting resulted in similar increases in endothelial progenitor cell numbers and showed equivalent proliferation activity. However, endothelial progenitor cell migratory function was higher in off-pump patients (25.3 +/- 5.0 vs 5.0 +/- 1.0 cells per high-powered field for off-pump vs on-pump coronary artery bypass grafting, respectively; P = .04). Postoperative endothelial progenitor cell viability adjusted for preoperative baseline was also higher after off-pump than on-pump coronary artery bypass grafting by 72.4% +/- 14.6% (P = .01). Endothelial progenitor cells of on-pump patients were less viable after surgery than before surgery, whereas the reverse was observed in off-pump patients. CONCLUSIONS: Both on-pump and off-pump coronary artery bypass grafting elicit mobilization of endothelial progenitor cells into the peripheral blood. On-pump coronary artery bypass grafting, however, impairs the migratory function and viability of these vascular repair cells, which are conversely preserved after off-pump surgery. Further work is necessary to determine whether the function and viability of endothelial progenitor cells correlate with vascular outcomes and whether their therapeutic modulation may one day benefit coronary artery bypass grafting patients.     

Resource utilization in on- and off-pump coronary artery surgery: factors influencing postoperative length of stay--an experience of 1,746 consecutive patients undergoing fast-track cardiac anesthesia

OBJECTIVE: The purpose of the present investigation was to examine factors influencing resource utilization in patients undergoing on-pump coronary artery bypass graft and off-pump coronary artery bypass (OPCAB) graft surgery at a major university hospital. The resources examined were time to extubation, packed red blood cell (PRBC) transfusion, intensive care length of stay (ICULOS), preoperative and postoperative length of stay (PLOS), and total length of stay (LOS). DESIGN: Observational study of consecutive patients undergoing on- and off-pump coronary artery bypass surgery. SETTING: Tertiary care cardiac referral center. PARTICIPANTS: One thousand seven hundred forty-six consecutive male and female patients undergoing primary coronary artery bypass graft (CABG) surgery over a period of 3 years (1999-2001). Eight hundred eighty-one patients underwent CABG with pump, and 865 patients underwent off-pump coronary artery bypass (OPCAB) surgery. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The mean time to extubation after surgery was 7.4 hours for on-pump patients and 5.8 hours for the OPCAB group (p72 hours to postoperative tracheal extubation compared with 1.5% in the OPCAB group (p=0.041). Hospital mortality was 2.7% for the on-pump group and 1.0% for the OPCAB group (p=0.010). CONCLUSION: The authors found that patients undergoing on-pump CABG have significantly longer time to tracheal extubation, increased blood use, longer ICULOS, PLOS, and total LOS and higher in-hospital mortality, which would translate into significant differences in the expenses associated with these 2 surgical approaches to coronary surgery.     

Effect of risk-adjusted, non-dialysis-dependent renal dysfunction on mortality and morbidity following coronary artery bypass surgery: a multi-centre study

Objective: As little is known about the impact of non-dialysis-dependent renal dysfunction on short- and mid-term outcomes following coronary surgery we have conducted a large multi-centre study comparing patients with no history of renal dysfunction to those with preoperative renal dysfunction. Methods: Data was prospectively collected on 19,625 consecutive patients undergoing isolated coronary surgery between 1997 and 2003 from four institutions. Sixty-seven patients had a history of dialysis support prior to coronary surgery, and were excluded from the main analysis of the study. The remaining 19,558 patients were divided into two groups based on preoperative serum creatinine level, patients with preoperative renal dysfunction with serum creatinine levels >200 μmol/L without dialysis support and control patients with preoperative serum creatinine levels <200 μmol/L. Case-mix was accounted for by developing a propensity score, which was the probability of belonging to the non-dialysis-dependent renal dysfunction group, and included in the multivariable analyses. Results: There were 19,172 patients with preoperative serum creatinine levels <200 μmol/L and 386 patients with serum creatinine levels >200 μmol/L without dialysis support. The propensity score included sex, body mass index, co-morbidity factors (respiratory disease, diabetes, cerebrovascular disease, hypertension, and hypercholesterolemia), ejection fraction, left main stem stenosis, emergency status, prior cardiac surgery, off-pump surgery, and the logistic EuroSCORE. After adjusting for the propensity score, patients with preoperative non-dialysis-dependent renal dysfunction had significantly higher in-hospital mortality (adjusted odds ratio 3.0, p < 0.001), stroke (adjusted odds ratio 2.0, p = 0.033), atrial arrhythmia (adjusted odds ratio 1.5, p = 0.003), prolonged ventilation (adjusted odds ratio 2.1, p < 0.001), and post-op stay > 6 days (adjusted odds ratio 2.6, p < 0.001). One thousand one hundred and eighty-three (6.1%) deaths occurred during 58,062 patient-years follow-up. After adjusting for the propensity score, the adjusted hazard ratio of mid-term mortality for non-dialysis-dependent renal dysfunction was 2.7 (p < 0.001). Conclusions: Patients undergoing coronary surgery with non-dialysis-dependent renal dysfunction have significantly increased perioperative morbidity and mortality. Mid-term survival is also significantly reduced at 5-years.     

Does off‐pump coronary artery bypass grafting beneficially affect renal function?

BACKGROUND: Off-pump coronary artery bypass grafting (CABG) has been reported to beneficially affect renal function, but this remains to be confirmed. The purpose of the present paper was to study the effects of off-pump CABG on renal function and analyse predictors of postoperative renal impairment in patients who received off-pump CABG. METHODS: A total of 451 patients who underwent isolated CABG between January 1999 and August 2003 were retrospectively studied. No patient was receiving dialysis. A total of 300 patients (228 men) underwent off-pump CABG (off-pump group) and 151 patients (104 men) underwent on-pump CABG (on-pump group). Perioperative serum creatinine levels and creatinine ratios (peak postoperative creatinine level/preoperative creatinine level) were compared between the groups. RESULTS: Renal impairment (serum creatinine >1.5 mg/dL) developed postoperatively in 12.7% of the off-pump group and 18.5% of the on-pump group (P = 0.1). The creatinine ratio was significantly lower in the off-pump group (1.2 +/- 0.4) than in the on-pump group (1.4 +/- 0.7, P = 0.003). Logistic regression analysis demonstrated that the strongest predictors of postoperative renal impairment in off-pump CABG were left ventricular dysfunction (odds ratio 10.8) and multivessel grafting (odds ratio 4.3). CONCLUSIONS: Off-pump CABG provides better renal protection than on-pump CABG. However, perioperative renal function should be closely monitored in patients who have left ventricular dysfunction or who undergo multivessel grafting, even when off-pump CABG is performed.     

Effect of off-pump and on-pump coronary artery bypass grafting on renal function

BACKGROUND: Coronary artery bypass grafting (CABG) with cardiopulmonary bypass (CPB) has the risk of renal dysfunction. The cause of renal dysfunction after CPB is multifactorial, such as nonpulsatile flow, renal hypoperfusion, hypothermia, and duration of CPB. This study compared off-pump technique with on-pump technique on renal function in patients who underwent CABG. METHODS: Sixty patients with normal preoperative renal functions undergoing CABG were randomly assigned to conventional revascularization with CPB (on-pump) or beating heart revascularization (off-pump). Renal functions were assessed up to 10 days postoperatively. RESULTS: Creatinine clearance was found to be significantly higher in the off-pump group than in the on-pump group (p<.05). The off-pump group had significantly less increase in creatinine levels when compared with the on-pump group (p<.05). The free water clearance values decreased similarly in both groups; however, the recovery was more prompt in the off-pump group (p<.05). No significant differences were found in the prevalence of postoperative hemodialysis. CONCLUSION: The off-pump technique may provide a positive contribution and sufficient protection on postoperative renal functions in patients undergoing CABG.     

Effect of avoiding cardiopulmonary bypass in non-elective coronary artery bypass surgery: a propensity score analysis.

OBJECTIVE: Non-elective coronary artery surgery (emergent/salvage or urgent) carries an increased risk in most risk-stratification models. Off-pump coronary surgery is increasingly used in non-elective cases. We aimed to investigate the effect of avoiding cardiopulmonary bypass on outcomes following non-elective coronary surgery. METHODS: Of the 3771 consecutive coronary artery bypass procedures performed by five surgeons between April 1997 and March 2002, 828 (22%) were non-elective and 417 (50.4%) of these patients had off-pump surgery. Multivariate logistic regression was used to assess the effect of off-pump on in-hospital outcomes, while adjusting for treatment selection bias. Treatment selection bias was controlled for by constructing a propensity score from core patient characteristics, which was the probability of avoiding cardiopulmonary bypass. The C statistic for this model was 0.8. RESULTS: Off-pump patients were more likely to be hypertensive, stable, had less extensive disease and better left ventricular function. The left internal mammary artery was used in 91.8% (n=383) of off-pump patients compared to 79.3% (n=326) of on-pump cases (P<0.001). After adjusting for the propensity score, no difference in in-hospital mortality was observed between off-pump and on-pump (adjusted odds ratio (OR) 0.83 (95% confidence intervals (CI) 0.36-1.93); P=0.667). Off-pump patients were less likely to require intra-aortic balloon pump support (adjusted OR 0.44 (95% CI 0.21-0.96); P=0.039), less likely to have renal failure (adjusted OR 0.44 (95% CI 0.22-0.90); P=0.025), and have shorter lengths of stay (adjusted OR 0.51 (95% CI 0.37-0.70); P<0.001). Other morbidity outcomes were similar in both groups. CONCLUSIONS: In this experience, off-pump coronary surgery in non-elective patients is safe with acceptable results. Non-elective off-pump patients have a significantly reduced incidence of renal failure, and shorter post-operative stays compared to on-pump coronary artery bypass surgery.     

Release of S100B during coronary artery bypass grafting is reduced by off-pump surgery

Background. S100B, a plasma marker of brain injury, was compared after coronary artery bypass grafting with and without cardiopulmonary bypass (CPB).

Methods. Fourteen patients with off-pump operations and 18 patients with CPB were compared. Seven patients in the off-pump group underwent a minithoracotomy and received only an arterial graft, whereas 7 patients underwent sternotomy and received both an arterial and one or two vein grafts. S100B was measured in arterial plasma using an immunoassay with enhanced sensitivity.

Results. S100B before the operation was 0.03 μg/L. At wound closure, S100B in patients of the off-pump and CPB groups reached a maximum level of 0.22 ± 0.07 and 2.4 ± 1.5 μg/L, respectively (p < 0.001). No strokes occurred. Patients without CPB receiving arterial and vein grafts released slightly more S100B (p < 0.05) than patients with only arterial grafting. In patients undergoing CPB, S100B increased slightly before aortic cannulation (p < 0.001), to the same level as the maximum reached for the non-CPB group.

Conclusions. Coronary artery bypass grafting with CPB caused a 10-fold greater increase in S100B than off-pump grafting. S100B release after off-pump sternotomy with vein grafting was slightly greater than in arterial grafting through a minithoracotomy.     

Peripheral tissue metabolism during off-pump versus on-pump coronary artery bypass graft surgery: the microdialysis study

Objective: The aim of this study was to monitor and compare metabolic changes in the skeletal muscle during coronary artery bypass grafting surgery with and without cardiopulmonary bypass (CPB) by means of interstitial microdialysis. Glucose, lactate, pyruvate and glycerol were assessed as markers of basic metabolism and tissue perfusion. Methods: Twenty patients undergoing surgical myocardial revascularization were enrolled in this pilot study. Ten patients were operated on without CPB (group A, off-pump) and 10 patients using normothermic CPB (group B, on-pump). Interstitial microdialysis was performed by a CMA 60 (CMA/Microdialysis AB, Sweden) probe, inserted into the patient's left deltoid muscle. Microdialysis measurements were performed at 30 min intervals. Glucose, lactate, pyruvate and glycerol were measured in samples using a CMA 600 Analyser (CMA/Microdialysis AB, Sweden). Results in both groups were statistically processed and the groups were compared. Results: Both groups were similar with regards to preoperative characteristics. Dynamic changes of interstitial concentrations of the measured analytes were found in off-pump (group A) and on-pump (group B) patients during the operation. There were no significant differences in dialysate concentrations of glucose and lactate between the groups. Significant differences were detected in pyruvate concentrations, lactate–pyruvate ratio and glycerol concentrations between off-pump versus on-pump patients. Pyruvate concentrations were higher in the off-pump group (p < 0.05), the lactate–pyruvate ratios indicating the aerobic/anaerobic metabolism status were lower in the off-pump group (p < 0.01) and the values of the concentrations of glycerol were lower in the off-pump group (p < 0.01). Conclusion: Dynamic changes in the interstitial concentrations of the glucose, glycerol, pyruvate and lactate were found in both groups of patients (off-pump and on-pump). The presented preliminary results suggest that extracorporeal circulation during cardiac operations could compromise skeletal muscle energy metabolism.     

Off-pump versus on-pump coronary artery bypass grafting outcomes stratified by preoperative renal function

Clinical trials of off-pump coronary artery bypass grafting (CABG) have largely excluded patients with CKD. Here, we sought to determine whether pump status affects outcomes in patients with CKD. Using a nonrandomized cohort of 742,909 non-emergent, isolated CABG cases, which included 158,561 off-pump cases, in the Society of Thoracic Surgery Database from 2004 through 2009, we evaluated the association between pump status (off-pump versus on-pump) and in-hospital death or incident renal replacement therapy (RRT) across strata of preoperative renal function. We used propensity methods to adjust patient- and center-level analyses for imbalances in baseline patient risk. Patients who received on-pump and off-pump CABG had similar mean age and distribution of preoperative estimated GFR (eGFR). In a propensity-weighted analysis, off-pump CABG was associated with a reduction in the composite in-hospital death or RRT, with patients having lower preoperative renal function exhibiting greater benefit, on average. The risk difference (on-pump minus off-pump) ranged from 0.05 (95% confidence interval, -0.06 to 0.16) per 100 patients for eGFR ≥ 90 ml/min per 1.73 m(2) to 3.66 (95% confidence interval, 2.14-5.18) per 100 patients for eGFR 15-29 ml/min per 1.73 m(2). Both component endpoints suggested the same trend. In summary, these data suggest that patients with CKD experience less death or incident RRT when treated with off-pump compared with on-pump CABG. The reduction in incident RRT, not death, drove this effect on the composite among patients with low eGFR. Prospective trials comparing these procedures in patients with impaired preoperative renal function are warranted.     

Symmetry aortic connector devices and acute renal injury: a comparison of renal dysfunction after three different aortocoronary bypass surgery techniques

Although the pathogenesis of acute renal injury after cardiac surgery is multifactorial, atherosclerosis of the ascending aorta and embolic burden are strong independent predictors. Use of the Symmetry aortic connector device (ACD) for proximal anastomosis of coronary grafts may reduce ascending aortic atheroembolism. Therefore, we tested the hypothesis that off-pump coronary artery bypass (OPCAB) surgery performed using an ACD is associated with less postoperative renal dysfunction compared with conventional OPCAB or on-pump coronary artery bypass graft (CABG) surgery. Three-thousand-three-hundred consecutive patients undergoing non-emergent aortocoronary bypass surgery were retrospectively divided into three groups by surgical procedure; Group A: OPCAB with ACD (n = 124), Group B: standard OPCAB (n = 313), Group C: on-pump CABG (n = 2863). Postoperative peak fractional change in creatinine compared with baseline was used as a measure of renal outcome. Multivariable analysis did not identify ACD use as an independent predictor of postoperative peak fractional change in creatinine (P = 0.71), although the relationships of several known renal risk factors with postoperative peak fractional change in creatinine were confirmed. We could not find evidence that OPCAB surgery using ACDs reduces acute renal injury compared with standard OPCAB or CABG surgery.