Renal artery stenosis is not associated with the development of acute renal failure following coronary artery bypass grafting

BACKGROUND: Acute renal failure (ARF) is a frequent complication of coronary artery bypass grafting (CABG) surgery and is strongly associated with perioperative morbidity and mortality. We hypothesized that renal artery stenosis (RAS), causing occult renal ischemia, may be an important factor contributing to development of ARF after CABG surgery. METHODS: Preoperative and intraoperative data on 798 consecutive adult patients undergoing CABG surgery with cardiopulmonary bypass from February 1, 1995 to February 1, 1997 (who had also undergone an abdominal aortogram for the evaluation of RAS) were recorded and entered into a computerized database. The development of ARF was defined as a rise in serum creatinine of 1 mg/dL (88.4 micromol/L) above baseline postoperatively. The association between the presence of renal artery stenosis together with preoperative and intraoperative variables and the development of ARF was assessed by multivariate logistic regression. RESULTS: A total of 798 patients underwent isolated coronary bypass grafting, of which 18.7% demonstrated 50% or more RAS. ARF developed in 82 patients (10.2%), of which three (0.3%) required dialysis support. The mortality for patients who developed ARF was 14% (OR 15, P=0.0001) compared to 0.2% among those who did not develop ARF. The presence of renal artery stenosis of any severity ranging from unilateral 50% RAS to bilateral 95% RAS was not associated with the subsequent development of ARF. CONCLUSIONS: The development of ARF following CABG surgery is associated with high mortality. The presence of RAS does not appear to increase the risk for developing ARF.     

Coronary revascularization with or without cardiopulmonary bypass in patients with preoperative nondialysis-dependent renal insufficiency

Background. Preoperative renal insufficiency is a predictor of acute renal failure in patients undergoing conventional coronary artery bypass grafting. Off-pump coronary artery bypass operations have been shown to reduce renal dysfunction in patients with normal renal function, but the effect of this technique in patients with preoperative nondialysis-dependent renal insufficiency is unknown.

Methods. From June 1996 to December 1999, data of 3,250 consecutive patients undergoing coronary artery bypass grafting were prospectively entered into the Patient Analysis & Tracking Systems (PATS, Dendrite Clinical Systems, London, UK). Two hundred and fifty-three patients with preoperative serum creatinine more than 150 μmol/L were identified (202 patients on-pump, 51 patients off-pump), and clinical outcomes were analyzed. Serum creatinine and urea, in-hospital mortality, and morbidity were compared between groups. The association of perioperative factors with acute renal failure was investigated by multiple logistic regression analysis.

Results. Preoperative characteristics were similar between the groups. Mean number of grafts was 2.9 ± 0.8 and 2.3 ± 0.8 in the on-pump and off-pump groups, respectively (p < 0.0001). Comparison between groups showed a significantly higher incidence of stroke, inotropic requirement, blood loss, and transfusion of red packed cell and platelets in the on-pump group (all p < 0.05). Postoperative serum creatinine and urea were higher in the on-pump group with a significant difference at 12 hours postoperatively (p < 0.05). Logistic regression analysis identified cardiopulmonary bypass, serum creatinine level 60 hours postoperatively, inotropic requirement, need for intraaortic balloon pump, transfusion of red packed cell, and hours of ventilation as predictors of postoperative acute renal failure.

Conclusions. This study suggests that off-pump coronary artery bypass operations reduce in-hospital morbidity and the likelihood of acute renal failure in patients with preoperative nondialysis-dependent renal insufficiency undergoing myocardial revascularization.     

Valvular heart operation is an independent risk factor for acute renal failure

BACKGROUND: Acute renal failure (ARF) after cardiac operation with cardiopulmonary bypass is associated with a high mortality rate. The purpose of this study was to determine and quantify whether valvular heart operation is an independent risk factor for developing ARF. METHODS: We retrospectively analyzed 5,132 consecutive patients who underwent cardiac operation involving cardiopulmonary bypass between April 1997 and March 2001. Patients with significant renal impairment (preoperative serum creatinine > 200 micromol/L) were excluded. A multivariable logistic regression model was constructed to identify independent risk factors for the postoperative development of ARF. RESULTS: In 151 (2.9%) patients ARF developed before hospital discharge. The crude incidence of ARF for isolated coronary artery bypass grafting, isolated valve(s) operation, and valve(s) with coronary artery bypass grafting operation was 1.9%, 4.4%, and 7.5%, respectively (p < 0.001). The results of the logistic regression analysis found that valve operation with or without coronary artery bypass grafting was an independent risk factor for the development of postoperative ARF (odds ratio 2.68, 95% confidence interval 1.89 to 3.79; p < 0.001). Other independent predictors of ARF were increased preoperative serum creatinine levels, urgent or emergent operation, insulin-dependent diabetes, and increased cardiopulmonary bypass time. CONCLUSIONS: Valve operation is an independent risk factor for postoperative ARF. This risk is further increased by prolonged cardiopulmonary bypass.     

Acute renal failure following cardiac surgery.

BACKGROUND: Acute renal failure requiring dialysis (ARF-D) occurs in 1.5% of patients following cardiac surgery, and remains a cause of major morbidity and mortality. While some preoperative risk factors have been characterized, the influence of preoperative and intraoperative factors on the occurrence of ARF following cardiac surgery is less well understood. METHODS: Preoperative and intraoperative data on 2843 consecutive adult patients undergoing cardiac surgery with cardiopulmonary bypass (CPB) from February 1, 1995 to February 1, 1997 were recorded and entered into a computerized database. Two definitions of renal failure were employed: (i) ARF defined as a rise in serum creatinine (Cr) of 1 mg/dl above baseline; and (ii) ARF-D defined as the development of ARF for which some form of dialytic therapy was required. The association between preoperative and intraoperative variables and the development of ARF was assessed by multivariate logistic regression. RESULTS: A total of 2672 of the 2844 patients underwent isolated coronary artery bypass grafting (CABG) surgery, the remaining 172 underwent valve surgery with or without bypass grafting. Of the CABG patients 7.9% developed ARF and 0.7% developed ARF-D. The mortality for patients who developed ARF was 14% (OR 15, P = 0.0001) compared with 1% among those who did not develop ARF. The mortality for CABG patients who developed ARF-D was 28% (OR 20, P = 0.0001) compared with 1.8% among those who did not require dialysis. Variables that were significantly associated with the development of ARF by multivariate analysis included: increased age, elevated preoperative serum Cr, duration of CPB, presence of a carotid artery bruit, presence of diabetes, reduced cardiac ejection fraction and increased body weight. Variables independently associated with ARF-D included serum Cr, duration of CPB, carotid artery bruit and presence of diabetes. The utility of these models for predicting the development of ARF and ARF-D was confirmed by bootstrapping techniques. Because of the small number of patients who underwent valve surgery, none of these variables were significantly associated with the development of ARF or ARF-D in this group of patients. CONCLUSION: The development of ARF or ARF-D is associated with a high mortality following CABG surgery. We have identified perioperative variables, which may be useful in stratifying risk for the development of ARF.     

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.     

Decreasing significance of left ventricular dysfunction and reoperative surgery in predicting coronary artery bypass grafting-associated mortality: a twelve-year study

OBJECTIVES: Patients undergoing coronary artery bypass grafting are older and have greater comorbidity than those operated on previously. We evaluated the changes in the predictors of in-hospital mortality among patients undergoing coronary artery bypass grafting during the last 12 years. METHODS: Data on demographic characteristics, preoperative risk factors, operative variables, and hospital outcomes were collected prospectively for all patients undergoing isolated coronary artery bypass grafting at a single institution from January 1, 1990, to December 31, 2001. To examine the effect of time on patient risk profiles and outcomes, we divided patients into three groups according to year of operation (1990-1993 n = 5171, 1994-1997 n = 5977, 1998-2001 n = 6893). RESULTS: In-hospital mortality declined from 2.4% (1990-1993) to 1.2% (1998-2001, P <.0001). Left ventricular dysfunction, increasing age, female gender, hypertension, diabetes, cardiogenic shock, congestive heart failure, peripheral vascular disease, reoperative coronary artery bypass grafting, left main disease, and urgent surgery independently predicted in-hospital mortality in the entire cohort of 18,041 patients. Severe left ventricular dysfunction was the most significant predictor of in-hospital mortality in the 12-year cohort, but it had a declining influence with time (1990-1993 odds ratio 7.1, 1994-1997 odds ratio 5.1, 1998-2001 not statistically significant) because of improving outcomes. Reoperative coronary artery bypass grafting similarly decreased in significance as a predictor of mortality. Emergency coronary artery bypass grafting was performed less frequently in recent years, but the requirement for emergency surgery carried an increasing odds ratio for mortality. CONCLUSIONS: Despite increasing patient age and comorbidity, improvements in perioperative management have reduced the significance of severe left ventricular dysfunction and reoperative coronary artery bypass grafting but not emergency surgery as predictors of in-hospital mortality.     

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.     

Acute renal failure related to open-heart surgery

Open-heart surgery was performed on 1686 adult patients between 1980 and 1984. The patients were operated on using cardiopulmonary bypass procedures (CPB). Fifteen patients developed acute renal failure (ARF) after CPB, i.e. the incidence of ARF was 0.9%. All these patients were treated by peritoneal dialysis or haemodialysis. Pre-operative possible risk factors in the ARF group were compared to those in a control group of 30 patients (15 consecutive coronary artery bypass grafting and 15 consecutive valve repair procedures) experiencing no complications. Age, New York Heart Association (NYHA) classification, ejection fraction, cardiac volume and left ventricular end-diastolic pressure were not risk factors for the development of renal failure. The incidence of thrombocytopenia after CPB was statistically significantly different between the control and ARF groups. The mortality from ARF was 66.6%. The causes of death were peri-operative myocardial infarction, infection and gastrointestinal bleeding. CPB time, perioperative events and postoperative infection were the main factors contributing to ARF. Renal failure was twice as common in valve procedures as in coronary artery revascularization procedures. Impairment of renal function proved reversible only in those patients who survived. After restoration of renal function the prognosis was good.     

Results of coronary artery bypass grafting in end-stage renal disease

We examined the results of coronary artery bypass grafting (CABG) in patients with end-stage renal disease and symptomatic ischemic heart disease who had significant arteriosclerotic narrowing of one or more coronary vessels between 1970 and 1984. Twenty-four such patients underwent bypass grafting, 20 dialysis patients and four who had been transplanted. Bypass grafting completely or partially relieved symptoms in 83%. The hospital mortality associated with this surgery for the 20 dialysis patients was 20% compared with a lower overall hospital mortality for bypass grafting in nondialysis patients of 1.3%. Greater hospital mortality was noted for patients over age 60 undergoing bypass grafting, 33.3% v 1.9% in nondialysis patients. In this study, the most significant factor associated with mortality was older age. We conclude that bypass grafting has an acceptable mortality in younger end-stage renal disease patients anticipating or having had renal transplantation, but it is associated with a high hospital mortality in older dialysis patients.     

On-pump versus off-pump coronary artery bypass grafting: impact on postoperative renal failure requiring renal replacement therapy

BACKGROUND: Despite refinements in perioperative patient management postoperative renal failure requiring hemofiltration or dialysis is still a common complication after coronary artery bypass grafting associated with impaired patient outcome. METHODS: Prospective data on 9,631 patients receiving myocardial revascularization with (coronary artery bypass grafting [n = 8,870]) or without cardiopulmonary bypass (off-pump coronary artery bypass grafting [n = 761]) between April 1996 and August 2001 were evaluated by univariate and multivariate logistic regression analysis. RESULTS: Overall prevalence of postoperative continuous renal replacement therapy was 4.1% (coronary artery bypass grafting, 4.3%; off-pump coronary artery bypass grafting, 1.8%; p = 0.001). Thirty of 40 selected preoperative and intraoperative patient and treatment related variables had a high association with the requirement for postoperative renal replacement therapy; fifteen of these variables were independent predictors in the whole study population. Off-pump coronary artery bypass surgery was identified as having a significantly lower predictive value for postoperative continuous renal placement therapy. In the subgroup of patients undergoing off-pump coronary artery bypass grafting surgery, a second multivariate logistic regression model revealed preoperative cardiogenic shock, urgent operation, intraoperative low cardiac output, and high transfusion requirement as independent predictors for postoperative renal replacement therapy. CONCLUSIONS: Patients with preoperative nondialysis dependent renal insufficiency are at a high risk for further decline in renal function requiring postoperative continuous renal replacement therapy. Off-pump coronary artery bypass surgery is associated with a lower prevalence of postoperative renal replacement therapy after coronary artery bypass grafting.     

Coronary artery bypass grafting in non-dialysis-dependent mild-to-moderate renal dysfunction

OBJECTIVES: The effect of mild-to-moderate elevation of preoperative serum creatinine levels on morbidity and mortality from coronary artery bypass grafting has not been investigated in a large multivariable model incorporating preoperative and intraoperative variables. Our first objective was to ascertain the effect of a mild-to-moderate elevation in the preoperative serum creatinine level on the need for mechanical renal support; the duration of special care and total postoperative stay; the occurrence of infective, respiratory, and neurologic complications; and hospital mortality. Our second objective was to ascertain which patient variables contributed to an increase in the serum creatinine level in association with coronary artery bypass grafting. METHODS: A total of 1427 patients who had no known pre-existing renal disease and who were undergoing first-time coronary artery bypass grafting with cardiopulmonary bypass were recruited for the study. Patients were divided, on the basis of preoperative serum creatinine level, into 3 groups as follows: creatinine level of less than 130 micromol. L(-1); creatinine level of 130 to 149 micromol. L(-1); and creatinine level of 150 micromol. L(-1) or greater. A multivariable stepwise logistic regression analysis was used, and variables significant at the 5% level were included when developing the final multivariable models. RESULTS: Multivariable analysis showed that elevation of the preoperative serum creatinine level to 130 micromol. L(-1) or greater increased the likelihood of needing mechanical renal support postoperatively (P <.001), as well as the need for postoperative special care (P <.001) and total hospital stay (P <.001). In-hospital mortality was also significantly elevated as the preoperative creatinine level rose to 130 to 149 micromol. L(-1) (P =.045) and to 150 micromol. L(-1) or greater (P <.001). It was further observed that patients with preoperative serum creatinine levels of 130 to 149 micromol. L(-1) (P =.02), patients with preoperative serum creatinine levels of 150 micromol. L(-1) or greater (P =.001), hypertensive patients (P =.007), patients with angina of New York Heart Association class III or greater (P =.001), patients having a nonelective operation (P =.002), and patients having a prolonged cardiopulmonary bypass time (P =.008) had a significantly greater increase in the serum creatinine level as a result of coronary artery bypass grafting. Of particular note was the finding that the method of myocardial protection (cardioplegia or crossclamp fibrillation) did not significantly influence in-hospital mortality, need for mechanical renal support, or special care or total postoperative hospital stay. CONCLUSIONS: A mild elevation (130-149 micromol. L(-1)) in the preoperative serum creatinine level significantly increases the need for mechanical renal support, the duration of special care and total postoperative stay, and the in-hospital mortality. As the preoperative serum creatinine level increases further (> or =150 micromol. L(-1)), this effect is more pronounced. No significant difference in outcome was observed between the use of cardioplegia or crossclamp fibrillation for myocardial protection.     

Acute renal failure after isolated CABG surgery: six years of experience

BACKGROUND: A prospective observational study was carried out in a Cardiosurgical Intensive Care Unit (ICU) in order to evaluate the incidence of Acute Renal Failure (ARF) after coronary artery bypass graft surgery and identify its predictors. The effects of ARF on outcome were also investigated. METHODS: The study enrolled 3,013 consecutive patients undergoing coronary artery bypass graft surgery. Baseline variables including age, sex, preoperative renal failure, left-ventricular dysfunction, emergency surgery, neurological adverse events, patient history of chronic obstructive pulmonary disease and diabetes mellitus were collected. Intraoperative variables were: type of surgery (on- or off-pump), intra-aortic balloon pump placement, and cardiopulmonary bypass duration. The measured postoperative variables were: low cardiac output syndrome, hemorrhage, transfusion of blood products, and surgical revision. RESULTS: Preoperative renal dysfunction (creatinine >1.4 mg/dL), blood transfusion, low-output syndrome, emergency surgery, low ejection fraction and age were independently associated with ARF. The median (interquartile range) ICU stay was 5.5 (range 4-11.5) days in patients who did and 1 (range 1-2) day in those who did not develop ARF (P<0.001). The median (interquartile range) hospital length of stay was 10 (range 8-21) days in patients who did and 5 (range 4-7) days in those who did not develop ARF (P<0.001). CONCLUSION: Preoperative renal dysfunction, blood transfusion, low-output syndrome, emergency surgery, low ejection fraction and age were independently associated with ARF. Length of ICU and hospital stay were reduced in patients not developing ARF.     

Differential survival after coronary revascularization procedures among patients with renal insufficiency.

BACKGROUND: Acute myocardial infarction, cardiac arrest, and other cardiac events are the major cause of mortality among patients with renal insufficiency. Previous studies of interventions for coronary artery disease among patients with renal insufficiency have not controlled for potentially confounding factors such as coronary artery disease severity and left ventricular function. This study investigates the comparative survival for patients with renal insufficiency and coronary artery disease following coronary artery bypass graft (CABG) surgery as compared with percutaneous coronary artery intervention (PCI), while controlling for confounding factors. METHODS: This retrospective cohort study of patients undergoing CABG surgery or PCI discharged between 1993 and 1995 uses the New York Department of Health databases and Cox proportional hazards analyses to estimate the mortality risk associated with CABG as compared with PCI for patients with renal insufficiency. Renal function was categorized as creatinine <2.5 mg/dL (N = 58,329), creatinine > or =2.5 mg/dL (N = 840), and end-stage renal disease (ESRD) requiring dialysis (N = 407). RESULTS: Patients with either ESRD or serum creatinine > or =2.5 mg/dL had more severe coronary artery disease and a greater frequency of comorbid conditions as compared with patients with creatinine <2.5 mg/dL. Creatinine > or =2.5 mg/dL and ESRD were both associated with an increased mortality risk among all distributions of coronary artery disease anatomy. Among patients with ESRD, the risk ratio (RR) of mortality for patients undergoing CABG compared with PCI was 0.39 (95% CI, 0.22 to 0.67, P = 0.0006). Among patients with creatinine > or =2.5 mg/dL, CABG surgery did not convey a survival benefit over PCI (RR, 0.86, 95% CI, 0.56 to 1.33, P = 0.50). CONCLUSIONS: This study demonstrates a survival benefit among patients with ESRD undergoing CABG surgery as compared with PCI, while controlling for severity of coronary artery disease, left ventricular dysfunction, and other comorbid conditions. These results suggest that management decisions among patients with coronary artery disease should be made in the context of not only location and severity of coronary artery lesions, but also on the presence and severity of renal dysfunction.     

Long-term results of coronary artery bypass grafting in patients with renal insufficiency

BACKGROUND: There are few published studies on coronary artery bypass grafting in patients with renal insufficiency who are not on maintenance dialysis. No details of long-term results have been published. METHODS: This retrospective study focuses on 117 consecutive coronary artery bypass grafting patients with renal insufficiency, but who did not require dialysis (group B: preoperative serum creatinine level > or = 1.5 mg/dL). For comparison purposes, patients on maintenance dialysis (group C: 84 patients) and patients with normal renal function (group A: 794 patients; preoperative serum creatinine level < 1.0 mg/dL) were selected. RESULTS: Hospital mortality was 11% (13 of 117) in group B, 5.9% (5 of 84) in group C, and 1.6% (13 of 794) in group A, and between groups A and B, p < 0.0001, and between groups B and C, p = 0.24. Actuarial survival rates at 10 years, including all deaths, were 87%, 32%, and 29% in groups A, B and C, respectively, and between groups A and B, p < 0.009 and between groups B and C, p = 0.63. In 23 patients in group B, the bilateral internal thoracic artery was used. No cardiac deaths were observed in these patients during the mean follow-up time of 42 months (range, 1 to 128 months). Cox model analysis revealed nonuse of arterial grafting (p = 0.03; Hazards ratio 1.7) to be a statistically significant factor, and renal insufficiency (p < 0.0001; Hazards ratio 3.3) and maintenance dialysis (p < 0.0001; Hazards ratio 5.6) to be major independent risk factors for actuarial survival. CONCLUSIONS: Renal insufficiency was shown to be an independent risk factor for poor prognosis after coronary artery bypass grafting. However, aggressive use of arterial grafts, especially the internal thoracic artery, is recommended to improve late outcomes.     

Early and intensive continuous veno-venous hemofiltration for acute renal failure after cardiac surgery

Various forms of renal replacement therapies are available to treat acute renal failure (ARF) after cardiac surgery. The objective of this study was to assess the incidence of ARF developing postoperatively necessitating continuous veno-venous hemofiltration (CVVH) in adult patients requiring cardiopulmonary bypass (CPB), to determine the factors which influence the outcome in these patients and to assess the outcome following the use of early and intensive CVVH. During the study period, i.e. August 2000 to July 2002, 2355 adult patients underwent surgery under CPB, of whom 159 (6.7%) developed renal failure (creatinine >200 micromol/l) and 116 (5%) needed CVVH. Patients excluded were those who died within 24 h and those who underwent coronary artery bypass grafting without utilising CPB, thoracoabdominal aneurysm operations and pericardial surgery. Average age, Parsonnet score and Euroscore in the study population were 69.9 years, 21 and 7.70, respectively. Of the 116, 45 died in the intensive care unit (38.8% mortality). Relatively more non-survivors suffered from diabetes and preoperative renal dysfunction (P<0.05). Adverse outcome was also more likely if patient suffered from postoperative cardiac failure or had gastrointestinal complications or had more than two organ systems failing (P<0.05). Mortality was 100% if hepatic failure ensued.     

Influence of renal dysfunction on mortality after cardiac surgery: modifying effect of preoperative renal function

BACKGROUND: Acute renal failure (ARF) requiring dialysis is an independent risk factor of mortality after cardiac surgery; the level of preoperative renal function influences the risk of both postoperative ARF and mortality. The relationship between mild renal dysfunction and mortality, and the modifying effect of baseline renal function on this association, is less clear. METHODS: We studied 31,677 patients undergoing cardiac surgery between 1993 and 2002. We used a logistic regression model to assess the relationship between postoperative renal dysfunction and mortality, while adjusting for preoperative renal function, postoperative ARF requiring dialysis, and other risk factors. RESULTS: The overall postoperative mortality rate was 2.2% (698/31,677). For the entire cohort, a clinically relevant increase in the adjusted risk of mortality occurred beyond 30% decline in postoperative GFR. The mortality rate was 5.9% (N, 292/4986) among patients who developed 30% or greater decline in postoperative GFR not requiring dialysis versus 0.4% (N, 106/26,136) among those with <30% decline (P < 0.001). A significant interaction between preoperative GFR and percent change in postoperative GFR (P < 0.001) indicated that at equivalent degrees of renal dysfunction, the mortality risk was greater at a lower preoperative GFR. ARF requiring dialysis was strongly associated with mortality in the model (odds ratio 4.2; 95% CI 3.1-5.7). CONCLUSION: Renal dysfunction not requiring dialysis is an independent risk factor of mortality after cardiac surgery. A better preoperative GFR attenuates the effect of postoperative renal dysfunction on mortality; this interaction needs to be considered while defining a clinically relevant threshold of ARF.     

Influence of diabetes on mortality and morbidity: off-pump coronary artery bypass grafting versus coronary artery bypass grafting with cardiopulmonary bypass

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 = 0.0127; 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.     

Coronary artery bypass grafting in patients with dialysis-dependent renal failure

This study identified preoperative characteristics of dialysis patients undergoing coronary artery bypass grafting (CABG) and determined the early and long-term results. We retrospectively analyzed the data of 60 patients (mean age 60.8 +/- 7.6 years) with end-stage renal disease who underwent CABG between 1982 and 1999. Seventeen (28%) patients underwent CABG for unstable angina, and 9 (15%) patients required preoperative intraaortic balloon pumping. The incidence of congestive heart failure (18%) and diseased aorta (42%) was higher in the dialysis group. In-hospital mortality in the dialysis group was 13% (8/60). The estimated survival rate at 5 and 10 years in the dialysis patients was 55.6 +/- 8.8% and 31.8 +/- 11.6%, respectively. The cardiac event-free rate, excluding the in-hospital mortality, was 62.5 +/- 9.9% at 5 years. Although the early and long-term results of CABG in dialysis patients were inferior to those of nondialysis patients, CABG in dialysis-dependent patients allows the patients to continue their dialysis therapy and to improve their functional status.     

Race and mortality after acute renal failure

Black patients receiving dialysis for end-stage renal disease in the United States have lower mortality rates than white patients. Whether racial differences exist in mortality after acute renal failure is not known. We studied acute renal failure in patients hospitalized between 2000 and 2003 using the Nationwide Inpatient Sample and found that black patients had an 18% (95% confidence interval [CI] 16 to 21%) lower odds of death than white patients after adjusting for age, sex, comorbidity, and the need for mechanical ventilation. Similarly, among those with acute renal failure requiring dialysis, black patients had a 16% (95% CI 10 to 22%) lower odds of death than white patients. In stratified analyses of patients with acute renal failure, black patients had significantly lower adjusted odds of death than white patients in settings of coronary artery bypass grafting, cardiac catheterization, acute myocardial infarction, congestive heart failure, pneumonia, sepsis, and gastrointestinal hemorrhage. Black patients were more likely than white patients to be treated in hospitals that care for a larger number of patients with acute renal failure, and black patients had lower in-hospital mortality than white patients in all four quartiles of hospital volume. In conclusion, in-hospital mortality is lower for black patients with acute renal failure than white patients. Future studies should assess the reasons for this difference.     

Late dialysis rate for coronary artery bypass grafting patients with moderate-to-severe renal impairment: comparison between off-pump and conventional method.

BACKGROUND: Whether off-pump coronary artery bypass grafting has a late renal protective advantage over conventional coronary arterial bypass grafting with cardiopulmonary bypass use is controversial. METHODS: From 1997 to 2004, 2102 cases of isolated coronary arterial bypass grafting were collected and analyzed, 1116 (53%) in the cardiopulmonary bypass group and 986 (47%) in the off-pump coronary artery bypass grafting group. Cases were stratified by preoperative estimated glomerular filtration rate into three renal groups: 1012 (48%) in group 1, with glomerular filtration rates > or =60 ml/h, 864 (41%) in group 2, with glomerular filtration rates of 30-60 ml/h, and 226 (10.8%) in group 3, with glomerular filtration rates <30 ml/h, but without dialysis before surgery. RESULTS: The in-hospital mechanical renal replacement therapy rates were 2.0%, 4.6%, and 26.1%, respectively, for the three renal groups that underwent coronary artery bypass grafting with conventional cardiopulmonary bypass, and 1.1%, 3.4%, and 14.0%, respectively for the three renal groups that underwent off-pump coronary artery bypass grafting. After risk adjustment, cardiopulmonary bypass use did not show statistical significance for in-hospital mechanical renal replacement therapy (p=0.314, 0.524, 0.150, respectively, across renal groups 1-3). At the end of the 4-year follow-up period, 99.1%, 97.2%, and 78.6%, respectively, of patients were free of mechanical renal replacement therapy across the three renal groups (p=0.0097 between renal groups 1 and 2; p<0.001 between renal groups 2 and 3). Cox regression analysis for renal groups 2 and 3 revealed that cardiopulmonary bypass use was not a risk factor for mid-term mechanical renal replacement therapy (p=0.452), but preoperative glomerular filtration rate, hypercholesterolemia, insulin-requiring diabetes, young age at surgery, female gender, and in-hospital mechanical renal replacement therapy use were. CONCLUSION: Patient characteristics, rather than operative strategy of using off-pump or conventional coronary artery bypass grafting, influence the mid-term mechanical renal replacement therapy rate for patients with glomerular filtration rates <60 ml/min.