Renal failure predisposes patients to adverse outcome after coronary artery bypass surgery. VA Cooperative Study #5

Impact of preoperative mild renal dysfunction on short term outcome in isolated Coronary Artery Bypass (CABG) patients

BACKGROUND AND AIM

It is well known that dialysis dependent renal failure increases the likelihood of poor outcome following cardiac surgery. But the results of CABG in patients with mild renal dysfunction are not clearly established. The aim of the study is to analyze the risk of preoperative mild renal dysfunction on outcome after isolated coronary surgery.

MATERIALS AND METHODS

We reviewed prospectively collected data between June 2006-Nov 2006 in 488 patients who underwent isolated CABG. We separated the data into two groups. Control group having normal renal function and study group having mild renal dysfunction (serum creatinine 1.4 mg-2.2 mg%). Among 488 patients, 412 patients were in control group and 76 patients were in the study group.

RESULTS

Analysis of data showed significant postoperative complications in the mild renal dysfunction group, like increased operative mortality (7.5% vs 1.6%), increased requirement of postoperative renal replacement therapy (10% vs 1.2%), increased incidence of new onset atrial fibrillation (20% vs 4.2%) and prolonged duration of ICU stay. Multivariate analysis adjusting for known risk factors confirmed preoperative mild renal dysfunction (S.creat.1.4-2.2 mg/dl) is an independent risk factor for postoperative morbidity and mortality. (Adj. OR: 4.47; 95% CI: 1.41-14.16; P=0.010).

CONCLUSION

Mild renal dysfunction is an important independent predictor of outcome in terms of in-hospital mortality and morbidity in patients undergoing CABG.

Emergency department lactate is associated with mortality in older adults admitted with and without infections

OBJECTIVES

Serum lactate values in the emergency department (ED) have been associated with mortality in diverse populations of critically ill patients. This study investigates whether serum lactate values measured in the ED are associated with mortality in older patients admitted to the hospital, both with and without infections.

METHODS

This is a retrospective cohort study performed at two urban teaching hospitals. The study population includes 1,655 older ED patients (age>or=65 years) over a 3-year period (2004-2006) who had serum lactate measured prior to admission. The presence or absence of infection was determined by review of International Classification of Diseases Ninth Revision (ICD-9) admission diagnosis codes. Mortality during hospitalization was determined by review of inpatient records. Mortality at 30 and at 60 days was determined using a state death registry.

RESULTS

In patients with infections, increasing serum lactate values of >or=2.0 mmol/L were linearly associated with relative risk (RR) of mortality during hospitalization (RR=1.9 to 3.6 with increasing lactate), at 30 days (RR=1.7 to 2.6), and at 60 days (RR=1.4 to 2.3) when compared to patients with serum lactate levels of <2.0 mmol/L. In patients without infections, a similar association was observed (RR=1.1 to 3.9 during hospitalization, RR=1.2 to 2.6 at 30 days, RR=1.1 to 2.4 at 60 days). In both groups of patients, serum lactate had a greater magnitude of association with mortality than either of two other commonly ordered laboratory tests, leukocyte count and serum creatinine.

CONCLUSIONS

Higher ED lactate values are associated with greater mortality in a broad cohort of admitted patients over age 65 years, regardless of the presence or absence of infection.

Intraoperative continuous venovenous hemofiltration during coronary surgery

Postoperative continuous venovenous hemofiltration decreases acute renal failure in patients with moderate renal dysfunction undergoing coronary artery bypass grafting, but it prolongs intensive care unit stay. We developed a simple method to connect a hemofiltration machine to the cardiopulmonary bypass system. To evaluate the benefit of intraoperative hemofiltration, 124 consecutive patients (mean age, 67 +/- 6 years) with moderate renal dysfunction were studied. Surgery was preformed between January 2005 and May 2007. On-pump coronary artery bypass with hemofiltration was carried out in 40 patients (group A), 44 had on-pump coronary artery bypass without hemofiltration (group B), and 40 had off-pump coronary artery bypass (group C). Postoperative acute renal failure was defined as either renal failure requiring dialysis or >or=50% decline from the baseline glomerular filtration rate but not requiring dialysis. The 3 groups had similar demographic data and preoperative renal function. After adjusting for covariates and propensity scores, multivariate analysis showed that intraoperative hemofiltration and off-pump surgery protected postoperative renal function. Independent risk factors for postoperative renal dysfunction were age >70 years, left ventricular ejection fraction <35%, and the preoperative glomerular filtration rate.

Perioperative outcomes among patients with end-stage renal disease following coronary artery bypass surgery in the USA

BACKGROUND

Patients with end-stage renal disease (ESRD) requiring chronic haemodialysis who undergo coronary artery bypass graft surgery (CABG) are at significant risk for perioperative mortality. However, the impact of changes in ESRD patient volume and characteristics over time on operative outcomes is unclear.

METHODS

Using the Nationwide Inpatient Sample database (1988-03), we evaluated rates of CABG surgery with and without concurrent valve surgery among ESRD patients and outcomes including in-hospital mortality, and length of hospital stay. Multivariate regression models were used to account for patient characteristics and potential cofounders.

RESULTS

From 1988 to 2003, annual rates of CABG among ESRD patients doubled from 2.5 to 5 per 1000 patient-years. Concomitantly, patient case-mix changed to include patients with greater co-morbidities such as diabetes, hypertension and obesity (all P < 0.001). Nonetheless, among ESRD patients, in-hospital mortality rates declined nearly 6-fold from over 31% to 5.4% (versus 4.7% to 1.8% among non-ESRD), and the median length of in-hospital stay dropped in half from 25 to 13 days (versus 14 to 10 days among non-ESRD).

CONCLUSIONS

Since 1988, an increasing number of patients with ESRD have been receiving CABG in the USA. Despite increasing co-morbidities, operative mortality rates and length of in-hospital stay have declined substantially. Nonetheless, mortality rates remain almost 3-fold higher compared to non-ESRD patients indicating a need for ongoing improvement.

The Adverse Long-Term Impact of Renal Impairment in Patients Undergoing Percutaneous Coronary Intervention in the Drug-Eluting Stent Era

Background— An observational study determining the long-term impact of chronic kidney disease (CKD) on patients undergoing percutaneous coronary intervention at a tertiary cardiac referral center. CKD is associated with poor in-hospital outcomes after percutaneous coronary intervention, but its effect beyond 1 year, particularly in the drug-eluting stent (DES) era, has not been reported.

Methods and Results— Baseline creatinine was available for 11 953 patients entered into a prospective registry (April 2000 to September 2007). Patients were stratified: those with or without at least moderate CKD (creatinine clearance, <60 mL/min). Follow-up data were obtained through linkage to a provincial registry. Kaplan–Meier analysis was performed. Cox multiple-regression analysis identified independent predictors of late mortality and major adverse cardiac events (MACE) and examined the association between DES use and late outcomes in the presence or absence of CKD. CKD was present in 3070 patients (25.7%). In-hospital mortality and MACE were significantly increased in CKD (3.34% versus 0.44%, P <0.001 and 5.73% versus 2.2%, P <0.001). Survival and MACE-free survival at 7 years were reduced (64.5�1.4% versus 89.4�0.5%, P <0.001; 44.0�1.4% versus 63.4�0.8%, P <0.001). CKD was an independent predictor of late mortality and MACE (hazard ratio [HR]: 2.18, CI: 1.90 to 2.49, P <0.0001; HR: 1.37, CI: 1.25 to 1.49, P <0.0001). DES use was associated with a significant reduction in both (HR: 0.71, CI: 0.60 to 0.83, P <0.0001; HR: 0.70, CI: 0.63 to 0.78, P <0.0001). In patients with CKD, DES use was associated with reduced revascularization (HR: 0.68, CI: 0.53 to 0.88, P =0.004) and reduced MACE (HR: 0.81, CI: 0.69 to 0.95, P =0.011) but not reduced mortality (HR: 0.85, CI: 0.69 to 1.05, P =0.1).

Conclusion— In a large registry of “all comers” for percutaneous coronary intervention, CKD was an independent predictor of adverse late outcomes. DES use may be associated with improved long-term outcomes in this high-risk cohort, but further prospective studies are required.

N-acetylcysteine is associated with increased blood loss and blood product utilization during cardiac surgery

OBJECTIVE

When used to prevent perioperative inflammation and ischemia-reperfusion injury, N-acetylcysteine may inadvertently impair hemostasis. We, therefore, performed a post hoc analysis of a recent randomized controlled trial in cardiac surgery to determine whether N-acetylcysteine was associated with increased blood loss and blood product transfusion.

DESIGN

Blinded (patients, caregivers, outcome assessors) placebo-controlled parallel group randomized trial (www.ClinicalTrials.gov ID NCT00188630).

SETTING

Tertiary care hospital in Toronto, Ontario, Canada (September 2003 to October 2005).

PATIENTS

A total of 177 patients with preexisting moderate renal insufficiency (estimated glomerular filtration rate <or=60 mL/min) and undergoing cardiac surgery.

INTERVENTIONS

Eighty-nine patients were randomized to receive intravenous N-acetylcysteine (100 mg/kg bolus; 20 mg.kg.hr infusion until 4 hours after cardiopulmonary bypass), and 88 were randomized to receive placebo.

MEASUREMENTS AND MAIN RESULTS

We used laboratory markers (hemoglobin, platelets, coagulation), chest-tube blood loss, and blood product transfusion to evaluate hemostasis. Compared with placebo, patients who received N-acetylcysteine arm experienced a mean 24-hour chest-tube blood loss that was 261 mL higher (95% confidence interval [CI] 93-488 mL, p = 0.008), and were transfused 1.6 more units of red blood cells (95% CI 0.4-3.1 units, p = 0.02) during hospitalization. The risk of receiving >or=5 units of red blood cells within 24 hours of surgery was significantly higher with N-acetylcysteine (relative risk 1.85, 95% CI 1.06-3.21, p = 0.03; adjusted relative risk 2.09, 95% CI 1.24-3.83, p = 0.005).

CONCLUSIONS

In patients who have preexisting moderate renal insufficiency and are undergoing cardiac surgery, N-acetylcysteine was associated with important effects on blood loss and blood product transfusion. Clinicians and researchers should, therefore, consider the potential for impaired hemostasis when using N-acetylcysteine in the perioperative setting. Further research is needed to elucidate mechanisms by which N-acetylcysteine may impair hemostasis, and the risk-benefit profile of N-acetylcysteine for perioperative organ protection.

Model for end-stage liver disease predicts mortality for tricuspid valve surgery

BACKGROUND

Patients undergoing tricuspid valve surgery have a mortality of 9.8%, which is higher than expected given the complexity of the procedure. Despite liver dysfunction seen in many patients with tricuspid disease, no existing risk model accounts for this. The Model for End-Stage Liver Disease (MELD) score accurately predicts mortality for abdominal surgery. The objective of this study was to determine if MELD could accurately predict mortality after tricuspid valve surgery and compare it to existing risk models.

METHODS

From 1994 to 2008, 168 patients (mean age, 61 +/- 14 years; male = 72, female = 96) underwent tricuspid repair (n = 156) or replacement (n = 12). Concomitant operations were performed in 87% (146 of 168). Patients with history of cirrhosis or MELD score 15 or greater (MELD = 3.8*LN [total bilirubin] + 11.2*log normal [international normalized ratio] + 9.6*log normal [creatinine] + 6.4) were compared with patients without liver disease or MELD score less than 15. Preoperative risk, intraoperative findings, and complications including operative mortality were evaluated. Statistical analyses were performed using chi(2), Fisher's exact test, and area under the curve (AUC) analyses.

RESULTS

Patients with a history of liver disease or MELD score of 15 or greater had significantly higher mortality (18.9% [7 of 37] versus 6.1% [8 of 131], p = 0.024). To further characterize the effect of MELD, patients were stratified by MELD alone. No major differences in demographics or operation were identified between groups. Mortality increased as MELD score increased, especially when MELD score of 15 or greater (p = 0.0015). A MELD score less than 10, 10 to 14.9, 15 to 19.9, and more than 20 was associated with operative mortality of 1.9%, 6.8%, 27.3%, and 30.8%, respectively. By multivariate analysis, MELD score of 15 or greater remained strongly associated with mortality (p = 0.0021). The MELD score predicted mortality (AUC = 0.78) as well as the European System for Cardiac Operative Risk Evaluation logistic risk calculator (AUC = 0.78, p = 0.96).

CONCLUSIONS

The MELD score predicts mortality in patients undergoing tricuspid valve surgery and offers a simple and effective method of risk stratification in these patients.

Impact of renal dysfunction on long-term survival after isolated coronary artery bypass surgery

BACKGROUND

Preoperative renal dysfunction has been an important predictor for adverse cardiovascular events after coronary artery bypass grafting (CABG). In the past, serum creatinine was widely used to assess renal function. Until recently, estimated glomerular filtration rate (eGFR) was recommended in evaluating renal function. The Cockcroft-Gault formula and the Modification of Diet in Renal Disease (MDRD) equation are two widely used formulas in clinical practice. Which method best predicts long-term outcome after CABG is still unknown. This study compared the predictive effectiveness of the Cockcroft-Gault formula, the MDRD equation, and serum creatinine level for in-hospital and long-term mortality.

METHODS

We retrospectively reviewed data collected from 5559 patients who underwent isolated CABG at Fuwai Hospital from January 1999 to December 2005. The main outcomes were in-hospital and long-term mortality. Receiver operating characteristic (ROC) curves and Cox analysis were used for the comparison.

RESULTS

Mean follow-up was 56.5 +/- 24.6 months. ROC curve analysis showed that the Cockcroft-Gault formula had the greatest accuracy for predicting in-hospital mortality (area under the curve, 0.755; p < 0.001). Multivariate analysis confirmed that the eGFR based on the Cockcroft-Gault formula was an independent predictor of in-hospital (odds ratio, 4.51, p < 0.001) and long-term (hazard ratio, 1.54; p = 0.003) mortality. Both formulas were better than the serum creatinine level.

CONCLUSIONS

Both formulas could provide a better measure of risk assessment than serum creatinine for in-hospital and long-term mortality. The Cockcroft-Gault formula was better than the MDRD equation for predicting in-hospital mortality.

Is preoperative serum creatinine a reliable indicator of outcome in patients undergoing coronary artery bypass surgery?

OBJECTIVE

Evaluating renal function by calculating creatinine clearance as an alternative measure to serum creatinine may give a better estimation of postoperative renal function in patients undergoing coronary artery bypass grafting.

METHODS

Using our database, we conducted a retrospective review of the records of all 11,884 patients aged 21 years or older undergoing pure bypass grafting who required cardiopulmonary bypass. Preoperative renal function was categorized as normal renal function (serum creatinine 60 mL/min), occult renal insufficiency (serum creatinine 1.5 mg/dL and creatinine clearance

RESULTS

Out of 11,884 patients in the sample, 7856 (66.1%) had normal renal function, and 706 (5.9%) had occult renal insufficiency. The rate of postoperative mortality, renal failure, atrial fibrillation, prolonged ventilation, intra-aortic balloon pump usage, and prolonged hospital stay (>7 days) was higher in patients with occult renal insufficiency than in the normal group in univariable analysis. Multivariable logistic regression analysis demonstrated that patients with occult renal insufficiency compared with the group with normal renal function were at higher risk for mortality (odds ratio = 2.59, 95% confidence interval 1.15-5.86; P = .022) and prolonged hospital stay (>7 d) (odds ratio = 1.30, 95% confidence interval 1.08-1.57; P = .005).

CONCLUSIONS

To identify higher-risk patients requiring special intensive care, and in whom new interventions can be performed to improve outcome, we recommend the preoperative calculation of creatinine clearance, especially in older women with a lower body mass index.

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MESH Headings

• Adult
• Aged
• Body Mass Index
• Comorbidity
• Coronary Artery Bypass/mortality
• Coronary Disease/epidemiology
• Coronary Disease/surgery
• Creatinine/blood
• Creatinine/metabolism
• Diabetic Angiopathies/surgery
• Female
• Humans
• Length of Stay
• Male
• Middle Aged
• Predictive Value of Tests
• Preoperative Care
• Retrospective Studies
• Treatment Outcome
• Young Adult

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Grants Collapse

Affiliation(s)

Mahdi Najafi Department of Anesthesiology, Tehran Heart Center, Medical Sciences/University of Tehran, Tehran, Iran
Hamidreza Goodarzynejad
Abbasali Karimi
Abbas Ghiasi
Hasan Soltaninia
Mehrab Marzban
Abbas Salehiomran
Banafsheh Alinejad
Maryam Soleymanzadeh

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The case for chronic kidney disease, diabetes mellitus, and myocardial infarction being equivalent risk factors for cardiovascular mortality in patients older than 65 years

The objective of the study was to determine whether chronic kidney disease (CKD) is as important a risk as either diabetes mellitus (DM) or previous myocardial infarction (MI). CKD and DM are important coronary artery disease risk factors. We hypothesized that the risk of cardiovascular mortality in elderly patients with CKD is equivalent to that for patients with either DM or previous MI. The CHS limited-access database was used to identify a cohort of patients with a baseline history of MI, DM, or CKD (estimated glomerular filtration rate <60 ml/min). Subjects were categorized in 1 of 3 groups as group 1, patients with DM (no CKD or MI); group 2, patients with previous MI (no DM or CKD); and group 3, patients with CKD (no DM or MI). Patients were followed up for a mean of 8.6 years, and rates of cardiovascular mortality were compared using proportional hazards regression. There were 789, 443, and 667 people in the MI, DM, and CKD groups, respectively. During follow-up, 124 patients (15.7%) died of cardiovascular causes in the MI group, and 69 (15.8%) and 87 (13%), in the DM and CKD groups, respectively. After adjusting for age, race, gender, smoking, hypertension, and total, high-density lipoprotein, and low-density lipoprotein cholesterol, the hazard ratio (HR) for cardiovascular mortality was similar between the DM (HR 1.0, 95% confidence interval 0.8 to 1.4)) and CKD cohorts (HR 0.8, 95% confidence interval 0.6 to 1.1) compared with the MI group. In conclusion, the risk of cardiovascular mortality in patients with moderate CKD was as high as that in patients with a history of MI or DM. Designation of CKD as a cardiovascular risk equivalent in patients >65 years of age appears justified.

Acute kidney injury and chronic kidney disease after cardiac surgery

Kidney dysfunction is common after cardiac surgery and predicts mortality risk and poorer long-term outcome, particularly when acute injury superimposes upon chronic kidney disease. Numerous insults contribute to perioperative renal impairment including major surgical trespass, procedure-specific interventions (eg, deep hypothermic circulatory arrest), and postoperative complications. Regardless of cause, evidence supports a role for renal impairment and accumulation of "uremic toxins" as direct contributors to adverse outcome. No one has yet characterized a loss of renal function small enough to be insignificant. Despite considerable research focus, progress in development of interventions aimed at perioperative renoprotection has been disappointing. However, practice modifications can influence the likelihood of acute kidney injury, and several recent advances provide hope for the future. We review pathophysiologic understanding of this disorder; evaluate the confusing relationship (causal v epiphenomena) among acute kidney injury, chronic kidney disease, and adverse outcome after cardiac surgery; and provide an evidence-based assessment of the conduct of cardiac surgery and renoprotection strategies.

Severity of chronic kidney disease as a risk factor for operative mortality in nonemergent patients in the California coronary artery bypass graft surgery outcomes reporting program

Guidelines published by the National Kidney Foundation in 2002 categorize renal failure into 5 stages of increasing severity. The relation of this classification to risk stratification for operative mortality in patients with nonemergent coronary artery bypass grafting (CABG) has not been clarified. We examined the effect of chronic kidney disease (CKD) severity on CABG operative mortality in patients with nonemergent CABG. Data reporting to the California CABG outcomes reporting program is mandated in California. Data from 121 hospitals on patients undergoing CABG in 2003 and 2004 were analyzed, including clinical characteristics, CKD stage, and operative mortality. CKD stage 1 and 2 were combined to form the reference group because data on urinary markers of renal failure were not available. Excluding patients with emergent or salvage acuity for CABG, 37,735 isolated CABGs were performed. Of these, 27,132 patients (71.9%) had glomerular filtration rate (GFR)>or=60 ml/min/1.73 m2; 8,861 (23.5%) had stage 3 CKD (GFR 30 to 59); 669 (1.8%) had stage 4 CKD (GFR 15 to 29); and 1,073 (2.8%) had stage 5 CKD (GFR<15 or on dialysis). In separate multivariate analyses, GFR and CKD stage were each significantly and independently associated with operative mortality (both p<0.0001). Operative mortality increased significantly with each stage of CKD (all p<0.01). Compared with the reference group, stage 3, (odds ratio [OR] 1.18, p=0.0374), stage 4 (OR 2.23, p<0.0001), and stage 5 (OR 4.39, p<0.0001) had increasingly higher operative mortality. In conclusion, CKD stage based on National Kidney Foundation guidelines is an important predictor in risk stratification for operative mortality in patients undergoing nonemergent CABG.

Perioperative medical comorbidities in the orthopaedic patient

Evaluation and management of medical comorbidities in the perioperative period can help improve surgical morbidity and mortality. Perioperative evaluation essentially is risk assessment and minimization. Patients undergoing orthopaedic treatment may benefit from temporizing measures to reduce systemic complications associated with some procedures. Patients at increased risk of cardiac ischemia should undergo risk stratification to determine possible perioperative interventions. Use of perioperative medications and/or consultation with specialists can help to address heart murmurs, bacterial endocarditis, prior stenting, heart failure, and hypertension. Patients with severe or unstable chronic obstructive pulmonary disease require the involvement of pulmonary care specialists. Renal failure can require nephrology consultation, particularly in cases of worsening renal function or urinary outflow obstruction. Hematologic considerations include bleeding and clotting. Prophylaxis should be used in patients with risk factors for peptic ulcer, as well as respiratory failure and hypotension. Nutritional status and liver disease also must be monitored and treated preoperatively. Orthopaedic diabetic patients should be placed on modified oral hypoglycemic or insulin regimens; recalcitrant cases merit consultation. Effective communication among all members of the patient's caregiving team is paramount.

N-acetylcysteine for prevention of acute renal failure in patients with chronic renal insufficiency undergoing cardiac surgery: a prospective, randomized, clinical trial

OBJECTIVE

To assess the preventive effect of the antioxidant N-acetylcysteine on postoperative acute renal failure in patients with renal insufficiency undergoing cardiac surgery.

DESIGN

Randomized, placebo-controlled, prospective study.

SETTING

University cardiology center.

PATIENTS

Two hundred fifty-four consecutive patients with chronic renal insufficiency (estimated creatinine clearance < or = 60 mL/min) undergoing elective cardiac surgery.

INTERVENTIONS

Patients were randomized to receive N-acetylcysteine (n = 129) or placebo (n = 125). Patients of the N-acetylcysteine group received four boluses of intravenous N-acetylcysteine (1200 mg every 12 hrs, starting immediately before cardiac surgery).

MEASUREMENTS AND MAIN RESULTS

The incidence of postoperative acute renal failure (> 25% increase in serum creatinine from baseline) and the in-hospital clinical course were evaluated. Acute renal failure occurred in 46% of patients and was associated with increased in-hospital mortality (7% vs. 0.7%; p = .024). It occurred in 52% of control patients and 40% of N-acetylcysteine-treated patients (p = .06). In-hospital mortality and need for renal replacement therapy were not affected by N-acetylcysteine, but a lower percentage of N-acetylcysteine-treated patients required mechanical ventilation prolonged for > 48 hrs (3% vs. 18%; p < .001) and had an intensive care unit stay > 4 days (13% vs. 33%; p < .001).

CONCLUSIONS

Intravenous administration of N-acetylcysteine does not clearly prevent postoperative acute renal failure in patients with renal insufficiency undergoing cardiac surgery.

Predictors of survival in patients with end-stage renal disease evaluated for kidney transplantation

Cardiovascular disease is the major cause of mortality in patients with end-stage renal disease (ESRD). This study examined the all-cause mortality in 3,698 patients with ESRD evaluated for kidney transplantation at our institution from 2001 to 2004. Mean age for the cohort was 48+/-12 years, and 42% were women. Stress myocardial perfusion imaging was done in 2,207 patients (60%) and coronary angiography in 260 patients (7%). There were 622 deaths (17%) during a mean follow-up period of 30+/-15 months. The presence and severity of coronary disease on angiography was not predictive of survival. Coronary revascularization did not impact survival (p=0.6) except in patients with 3-vessel disease (p=0.05). The best predictor of death was left ventricular ejection fraction, measured by gated myocardial perfusion imaging, with 2.7% mortality increase for each 1% ejection fraction decrease. In conclusion, left ventricular ejection fraction is a strong predictor of survival in patients with ESRD awaiting renal transplantation. Strategies to improve cardiac function or earlier renal transplantation deserve further studies.

Long-term outcomes after coronary artery bypass grafting: Preoperative kidney function is prognostic

OBJECTIVE

End-stage renal disease is an independent predictor of mortality after coronary artery bypass grafting. Limited information exists, however, regarding the impact of chronic kidney disease on long-term outcome after bypass grafting. The purpose of this study was to assess the impact of kidney function on long-term outcomes in patients undergoing coronary artery bypass grafting.

METHODS

We studied 931 consecutive patients undergoing coronary artery bypass grafting in a single center. Demographic and clinical data were collected preoperatively. Chronic kidney disease was defined preoperatively according to the Modification of Diet in Renal Disease equation as an estimated glomerular filtration rate less than 60 mL x min(-1) x 1.73 m(-2). Multivariate Cox proportional hazard analyses were performed to determine the independent prognostic factors after bypass grafting. The primary outcome was a composite, combining death, acute coronary syndrome, stroke or transient ischemic attack, and coronary or peripheral revascularization during follow-up. Secondary outcomes were overall causes of death and cardiovascular death, acute coronary syndrome, and stroke or transient ischemic attack.

RESULTS

One hundred fourteen (12.2%) patients had preoperative chronic kidney disease (estimated glomerular filtration rate range, 20.5-59.8 mL x min(-1) x 1.73 m(-2)). After a mean follow-up of 3.1 +/- 1.4 years (median, 3.3 years), chronic kidney disease was found to be an independent predictor of the composite outcome (hazard ratio and 95% confidence interval, 1.46 [1.01-2.11]; P = .0467) and overall death (hazard ratio and 95% confidence interval, 1.89 [1.16-3.07]; P = .0106).

CONCLUSIONS

Beyond the perioperative period, preoperative moderate-to-severe chronic kidney disease is an independent long-term predictor of cardiovascular events and total mortality after coronary artery bypass grafting. Chronic kidney disease status should be incorporated into prediction models and clinical risk assessments.

Cystatin C blood level as a risk factor for death after heart surgery

AIMS

Pre-operative renal dysfunction is a known risk factor for mortality and morbidity after heart surgery. Despite limited accuracy, serum creatinine is widely used to estimate glomerular filtration rate (GFR). Cystatin C is more accurate for assessing GFR. The aim of the present study was to assess associations between GFR estimated from serum cystatin C levels before heart surgery and hospital mortality, hospital morbidity, and 1 year mortality.

METHODS AND RESULTS

In a prospective single-centre observational study, clinical risk factors for morbidity and mortality were recorded and serum creatinine and cystatin C levels were measured in patients admitted for heart surgery. Hospital mortality and morbidity and 1 year mortality were recorded. Over an 8 month period, 499 patients were screened, among whom 376 (74.5%) were included in the study. Hospital mortality was 5.6% (21 patients) and 1 year mortality was 10.2%. Hospital morbidity, defined by a length of stay above the 75th percentile, was 22.1% (83 patients). In the multivariable analysis, GFR estimated from serum cystatin C, but not GFR estimated from serum creatinine, was an independent risk factor for hospital morbidity/mortality (odds ratio per 10 mL/min of GFR decrease, 1.20 (1.07-1.34), P = 0.001) and for 1 year mortality (hazards ratio per 10 mL/min of GFR decrease, 1.26 (1.09-1.46), P = 0.002).

CONCLUSION

Pre-operative GFR estimation from serum cystatin C may provide a better risk assessment than pre-operative GFR estimation from serum creatinine in patients scheduled for heart surgery.

Coronary artery bypass grafting with or without cardiopulmonary bypass in patients with preoperative non–dialysis dependent renal insufficiency: A randomized study

OBJECTIVE

Preoperative renal insufficiency is a predictor of acute renal failure in patients undergoing coronary artery revascularization with cardiopulmonary bypass. Off-pump coronary artery bypass grafting has been shown to be less deleterious than on-pump bypass in patients with normal renal function, but the effect of this technique in patients with non-dialysis dependent renal insufficiency in a randomized study is unknown.

METHODS

From August 2004 through October 2005, 116 consecutive patients with preoperative non-dialysis-dependent renal insufficiency (glomerular filtration rate measured using the Modification of Diet in Renal Disease equation [MDRD GFR] < or = 60 mL x min(-1) x 1.73 m(-2)) undergoing primary coronary artery bypass grafting were randomized to on-pump (n = 60) and off-pump (n = 56) groups. MDRD GFR and serum creatinine levels were measured preoperatively and postoperatively at days 1 and 5. The changes in renal function and clinical outcomes were compared between the two groups.

RESULTS

Preoperative characteristics were comparable between the two groups. The repeated-measures analysis of variance was performed on the data that showed worsening of renal function in the on-pump group compared with the off-pump group (serum creatinine, P < .000; glomerular filtration rate, P < .000). Further analysis of subgroups of patients with diabetes alone, hypertension alone, and combined hypertension and diabetes also showed significant deterioration renal function in the on-pump group compared with the off-pump group. In covariate analysis, diabetes has emerged as a significant covariate by serum creatinine criteria while compromised left ventricular function has emerged as a significant covariate by glomerular filtration rate criteria. These analyses showed that the use of cardiopulmonary bypass is significantly associated with adverse renal outcome (P < .000). Three patents required hemodialysis in the on-pump group and none in the off-pump group. The mean number of grafts per patient was 3.85 +/- 0.86 and 3.11 +/- 0.89 in the on-pump and off-pump groups, respectively (P < .001), but the indices of completeness of revascularization, 1.00 +/- 0.08 for off-pump coronary bypass and 1.01 +/- 0.08 for on-pump coronary bypass, were similar (P = .60).

CONCLUSIONS

This study suggests that on-pump as compared with off-pump coronary artery bypass grafting is more deleterious to renal function in diabetic patients with non-dialysis dependent renal insufficiency. MDRD GFR is a more sensitive investigation than serum creatinine levels to assess renal insufficiency in patients undergoing coronary bypass.

Creatinine clearance but not serum creatinine alone predicts long-term postoperative survival after lower extremity revascularization

BACKGROUND

Renal insufficiency is a well-described risk factor for perioperative morbidity and shortened survival after major vascular procedures. Due to the potential inaccuracy of serum creatinine levels alone in measuring kidney function, our aim was to determine whether estimated creatinine clearance more consistently predicted long-term survival.

METHODS

A retrospective review of one institution's vascular registry was performed. Logistic regression analysis was conducted to determine independent predictors of 1-, 2- and 3-year postoperative mortality. Creatinine clearance was estimated as [140 - age (years)] x weight (kg)/72 x serum creatinine (mg/dl), multiplied by 0.85 for women.

RESULTS

A total of 252 consecutive patients underwent infrainguinal bypass procedures between August 1999 and May 2000. Demographics included average age 68 years, 65% male, 74% diabetic, 12% dialysis-dependent, 23% history of congestive heart failure, 12% history of stroke and 20% serum creatinine >2 mg/dl. One-year mortality was 16% (n = 40), 2-year mortality was 25% (n = 64), and 3-year mortality was 35% (n = 88). There was no difference in serum creatinine values between survivors and non-survivors at 1 year (1.8 vs. 1.9, p = 0.80), 2 years (1.8 vs. 2.0, p = 0.62) or 3 years (1.8 vs. 2.0, p = 0.24), and creatinine >2 mg/dl did not predict long-term adverse outcomes. In contrast, reduced creatinine clearance (< or =60 ml/min) was an independent predictor of mortality regardless of dialysis status (1 year: OR = 2.53, p = 0.014; 2 years: OR = 2.46, p = 0.004; 3 years: OR = 2.45, p = 0.001), and creatinine clearance was higher for survivors versus non-survivors at all 3 time points (1 year: 70.2 vs. 49.5, p = 0.003; 2 years: 72.3 vs. 51.2, p < 0.0001; 3 years: 74.7 vs. 52.6, p < 0.0001). Other independent predictors of mortality included a history of stroke (1 year: OR = 3.28, p = 0.008; 2 years: OR = 2.55, p = 0.025; 3 years: OR = 2.35, p = 0.038) and congestive heart failure (1 year: OR = 2.86, p = 0.006; 2 years: OR = 2.54, p = 0.005; 3 years: OR = 2.13, p = 0.017).

CONCLUSIONS

Independent of dialysis status, a decreased creatinine clearance, but not elevated serum creatinine alone, is an independent predictor of mortality after lower extremity arterial reconstruction. Determination of creatinine clearance should replace serum creatinine in the preoperative risk evaluations of patients undergoing major vascular surgical procedures.

Extensive bleeding during surgical treatment for gingival overgrowth in a patient on haemodialysis--a case report and review of the literature

Before performing renal transplantation, a most important concern is to control any infection, including oral infections before transplantation. The bleeding diathesis of patients with uraemia is a significant clinical concern, especially when surgery is required. A 44-year-old female patient on haemodialysis was referred for evaluation of gingival overgrowth. The patient was planning a renal transplantation two months later. As the lesions were not considered successfully treatable before transplantation, a gingivectomy and teeth extraction was performed. In pre-operative examinations, an abnormal bleeding time was not detected and other coagulation tests were normal. Under general anaesthesia, 19 teeth were extracted and overgrown gingiva was removed. During the operation, extensive blood loss of 1650ml occurred and four units of concentrated red blood cells were transfused. This study suggests that patients with renal failure undergoing dental surgery require careful pre-surgical evaluation including assessment of their coagulation ability.

Occult renal impairment is common in patients with peripheral vascular disease and normal serum creatinine

OBJECTIVE

The incidence of peripheral vascular disease (PVD) and angiography/angioplasty is rising annually. The UK Small Aneurysm Trial and other trials have shown renal function is a predictor of increased mortality and failed infrainguinal bypass despite patent vessels. Renal function is classically assessed by serum creatinine (SCr). However, SCr can be normal despite significant renal impairment. A more sensitive test is creatinine clearance (CrCl) as determined by 24-hour urine collection in combination with SCr. We studied the incidence of renal impairment, as defined by CrCl, in PVD patients with normal SCr.

METHODOLOGY

All patients with PVD sufficient to necessitate angiography and normal SCr (< or =120 micromol/l - men; < or =97 micromol/l - women) had their CrCl assessed prior to angiography: using both 24-hour urine collection and the Cockcroft-Gault formula. Various blood tests, a detailed history and examination were performed. A control group of arthritic patients, age and sex-matched with similar SCr, also had their CrCl determined.

RESULTS

65 of 76 patients (86%) with normal SCr had a subnormal CrCl (<100 ml/min) and 49 (65%) had a CrCl below 60 ml/min. In the control group of arthritic patients, the proportion having impaired CrCl was significantly less - 67% below 100 mls/min (p=0.0471) and only 15% below 60 mls/min (p<0.0001). The median and interquartile range CrCl of 52 [38-81] mls/min for PVD patients was significantly worse than for control patients (80 [68-119] mls/min -p<0.0001). The Cockcroft-Gault formula for calculating CrCl did not correlate well with the urinary CrCl for the control group but did for PVD patients (p<0.0001). Factors associated with a significantly reduced CrCl were age of at least 75 years, SCr of at least 85 micromol/l and a history of coronary heart disease (all p<0.05). This had a sensitivity of 88% and specificity of 82% for identifying subnormal CrCl. Statin use was associated with a significantly improved CrCl (p=0.040).

CONCLUSION

Most PVD patients with normal serum creatinine have occult, significantly impaired renal function as defined by creatinine clearance. Vascular surgeons should include creatinine clearance in pre-operative assessment of renal function especially in patients over 75 years old, with a history of coronary heart disease or a serum creatinine over 85 micromol/l. The method of determining creatinine clearance could be the Cockcroft-Gault calculation or ideally 24-hour urinary creatinine clearance measurement. This would allow appropriate early referral to a nephrologist for further investigation and management. It is worth noting that statin use seems to be associated with a protective effect on renal function.

Failure of ICD-9-CM codes to identify patients with comorbid chronic kidney disease in diabetes

OBJECTIVE

To determine prevalence of chronic kidney disease (CKD) in patients with diabetes, and accuracy of International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) codes to identify such patients.

DATA SOURCES/STUDY SETTING

Secondary data from 1999 to 2000. We linked all inpatient and outpatient administrative and clinical records of U.S. veterans with diabetes dually enrolled in Medicare and the Veterans Administration (VA) health care systems.

STUDY DESIGN

We used a cross-sectional, observational design to determine the sensitivity and specificity of renal-related ICD-9-CM diagnosis codes in identifying individuals with chronic kidney disease.

DATA COLLECTION/EXTRACTION METHODS

We estimated glomerular filtration rate (eGFR) from serum creatinine and defined CKD as Stage 3, 4, or 5 CKD by eGFR criterion according to the Kidney Disease Outcomes Quality Initiative guidelines. Renal-related ICD-9-CM codes were grouped by algorithm.

PRINCIPAL FINDINGS

Prevalence of CKD was 31.6 percent in the veteran sample with diabetes. Depending on the detail of the algorithm, only 20.2 to 42.4 percent of individuals with CKD received a renal-related diagnosis code in either VA or Medicare records over 1 year. Specificity of renal codes for CKD ranged from 93.2 to 99.4 percent. Patients hospitalized in VA facilities were slightly more likely to be correctly coded for CKD than patients hospitalized in facilities reimbursed by Medicare (OR 5.4 versus 4.1, p=.0330)

CONCLUSIONS

CKD is a common comorbidity for patients with diabetes in the VA system. Diagnosis codes in administrative records from Medicare and VA systems are insensitive, but specific markers for patients with CKD.

Renal Function and Outcome From Coronary Artery Bypass Grafting

Background— Severe renal dysfunction is associated with a worse outcome after coronary artery bypass graft surgery (CABG). Less is known about the effects of milder degrees of renal impairment, and previous studies have relied on levels of serum creatinine, an insensitive indicator of renal function. Recent studies have suggested that estimated glomerular filtration rate (eGFR) is a more discriminatory measure. However, data on the utility of eGFR in predicting outcome from CABG are limited.

Methods and Results— We studied 2067 consecutive patients undergoing CABG. Demographic and clinical data were collected preoperatively, and patients were followed up a median of 2.3 years after surgery. Estimated GFR was calculated from the Modification of Diet in Renal Disease equation. The primary outcome was all-cause mortality. Mean±SD eGFR was 57.9±17.6 mL/min per 1.73 m 2 in the 158 patients who died during follow-up compared with 64.7±13.8 mL/min per 1.73 m 2 in survivors (hazard ratio [HR], 0.71 per 10 mL/min per 1.73 m 2 ; 95% CI, 0.64 to 0.80; P <0.001). Estimated GFR was an independent predictor of mortality in both models with other individual univariable predictors (HR, 0.80 per 10 mL/min per 1.73 m 2 ; 95% CI, 0.72 to 0.89; P <0.001) and the European system for cardiac operative risk evaluation (HR, 0.88 per 10 mL/min per 1.73 m 2 ; 95% CI, 0.78 to 0.98; P =0.02).

Conclusions— Estimated GFR is a powerful and independent predictor of mortality after CABG.

Impact of renal dysfunction on outcomes of coronary artery bypass surgery: results from the Society of Thoracic Surgeons National Adult Cardiac Database

BACKGROUND

Although patients with end-stage renal disease are known to be at high risk for mortality after coronary artery bypass graft (CABG) surgery, the impact of lesser degrees of renal impairment has not been well studied. The purpose of this study was to compare outcomes in patients undergoing CABG with a range from normal renal function to dependence on dialysis.

METHODS AND RESULTS

We reviewed 483,914 patients receiving isolated CABG from July 2000 to December 2003, using the Society of Thoracic Surgeons National Adult Cardiac Database. Glomerular filtration rate (GFR) was estimated for patients with the use of the Modification of Diet in Renal Disease study formula. Multivariable logistic regression was used to determine the association of GFR with operative mortality and morbidities (stroke, reoperation, deep sternal infection, ventilation >48 hours, postoperative stay >2 weeks) after adjustment for 27 other known clinical risk factors. Preoperative renal dysfunction (RD) was common among CABG patients, with 51% having mild RD (GFR 60 to 90 mL/min per 1.73 m2, excludes dialysis), 24% moderate RD (GFR 30 to 59 mL/min per 1.73 m2, excludes dialysis), 2% severe RD (GFR <30 mL/min per 1.73 m2, excludes dialysis), and 1.5% requiring dialysis. Operative mortality rose inversely with declining renal function, from 1.3% for those with normal renal function to 9.3% for patients with severe RD not on dialysis and 9.0% for those who were dialysis dependent. After adjustment for other covariates, preoperative GFR was one of the most powerful predictors of operative mortality and morbidities.

CONCLUSIONS

Preoperative RD is common in the CABG population and carries important prognostic importance. Assessment of preoperative renal function should be incorporated into clinical risk assessment and prediction models.

Single dose parecoxib significantly improves ventilatory function in early extubation coronary artery bypass surgery: a prospective randomized double blind placebo controlled trial

BACKGROUND

Parecoxib, a cyclo oxygenase-2 inhibiting non-steroidal anti-inflammatory drug, has been widely used for postoperative analgesia. Our aim was to quantify the benefit of a single dose after coronary artery bypass grafting.

METHODS

The investigation was carried out as a randomized double blind placebo controlled study. A single i.v. dose of parecoxib 40 mg or placebo was given at closure of sternotomy. No opioid other than morphine was given in the first 24 postoperative hours. Pain was assessed using both a Visual Analogue Score (1-10), and the amount of morphine used via a morphine patient controlled analgesia pump. Creatinine clearance was measured before and after operation from 24 h urine collections. After a global announcement by Pfizer that paracoxib was 'contraindicated in patients with ischaemic heart disease' further recruitment was suspended and the collected data from 40 patients were analysed.

RESULTS

Twenty-one patients received parecoxib and 19 received placebo. Amongst those who received parecoxib, there was a highly significant sparing of rescue medication before tracheal extubation (P=0.004) compared with placebo, and an overall 35% morphine sparing effect during the first 6 h post extubation after correction for the variability in extubation time (P=0.037). Respiration, as measured by arterial carbon dioxide tension at the time of extubation, was significantly better in the parecoxib group (P=0.045). Significantly more furosemide was given for postoperative oliguria in those patients who received parecoxib (P=0.036). After correcting for differences in diuretic usage and fluid balance, parecoxib was associated with a significant increase in plasma creatinine (P=0.041).

CONCLUSION

A single dose of parecoxib has a significant opioid sparing effect in the first 6 h after coronary artery bypass grafting which resulted in significantly improved ventilation with mild elevation of plasma creatinine within normal limits.

Moderate renal insufficiency at 70 years predicts mortality

BACKGROUND

Glomerular filtration rate (GFR) diminishes with age. Kidney function in the elderly is often assessed by serum creatinine alone, although it is insensitive in this age group. Formulae for predicting GFR are not widely used.

AIM

To study the effect of low predicted GFR on mortality.

DESIGN

Longitudinal cohort study.

SETTING

The community-based Jerusalem Seventy Year Olds Longitudinal Study.

METHODS

We studied 445 subjects, all aged 70 years, using questionnaires, a medical examination with history-taking, and standard laboratory tests. Moderate renal insufficiency was defined as a predicted GFR of <60 ml/min, based on the Cockcroft-Gault (CG) and the Modification of Diet in Renal Disease (MDRD) equations.

RESULTS

Predicted GFR was normally distributed, with a mean +/- SD of 62.4 +/- 15.27 ml/min. Predicted GFR was <60 ml/min in 221 (46%), most of whom had normal serum creatinine. Twelve-year mortality was 38.7% in these 221 vs. 27% in the other 204. The survival advantage was already evident after 3 years. Under Cox proportional hazard analysis using numerous common risk factors as independent variables, lower predicted GFR had a significant mortality risk (hazard ratio 2.108, 95%CI 1.43-3.12, p = 0.0002).

DISCUSSION

In community-dwelling elderly people, moderate renal insufficiency as assessed using the CG equation is a strong and independent predictor of mortality. Most of these at-risk patients have 'normal' serum creatinine.

Role of Diminished Renal Function in Cardiovascular Mortality

The interactions between the heart and the kidney recently have been the focus of intense interest because of epidemiological evidence indicating that even mild deterioration of renal function is an important risk factor for poor outcome in patients with congestive heart failure, myocardial infarction, and cardiovascular surgery. Kidney function deterioration may be a consequence of cardiac and baroreceptor dysfunction or may be primarily caused by intrinsic kidney disease. This review provides a comprehensive analysis of the role of the kidney not only as a marker but also as a pathogenic factor in cardiorenal syndromes, whether primary heart or primary kidney disease or both are the initiators of the subsequent pathophysiological events.

Impact of renal insufficiency on outcome after contemporary percutaneous coronary intervention

BACKGROUND

End-stage renal failure is associated with poor outcomes, including increased mortality, after percutaneous coronary intervention (PCI). The effect of milder degrees of renal insufficiency (RI) is less clear, especially with routine stenting and glycoprotein IIb/IIIa inhibitor therapy, which may be of particular benefit in patients with RI.

METHODS

Clinical, angiographic, procedural, and outcome variables of 7769 consecutive patients who underwent PCI between April 2000 and July 2004 were entered into a prospective database. Inhospital mortality and morbidity were calculated according to baseline creatinine clearance. Simple and multiple logistic regression analyses were performed to determine independent predictors of mortality.

RESULTS

Baseline creatinine clearance was available in 6840 patients. It was normal (> 80 mL/min) in 3474; 1670 had mild RI (61-80 mL/min), 1111 moderate RI (41-60 mL/min), and 585 severe RI (< or = 40 mL/min). Major adverse cardiac events (MACE) (death/myocardial infarction/revascularization) increased substantially with worsening renal function (2.4% vs 3.0% vs 4.8% vs 9.7%, P < .0001), as did mortality (0.3% vs 0.7% vs 1.5% vs 6.0%, P < .0001). Multiple logistic regression analysis identified moderate RI and severe RI as independent predictors of mortality (odds ratio [OR] 3.9, P < .001; OR 12.7, P < .0001, respectively) and morbidity (MACE) (OR 1.5, P < .05; OR 2.5, P < .0001, respectively). Mild RI trended to increase the risk of mortality but did not reach statistical significance as an independent predictor of inhospital death on multiple regression analysis (OR 2.1, P = .1) and did not increase the risk of MACE (OR 1.1, P = .6).

CONCLUSIONS

Despite routine stenting and glycoprotein IIb/IIIa inhibitor therapy, RI remains an independent predictor of increased morbidity, and particularly mortality, after PCI. However, the adverse effect of truly mild RI on outcome is limited.

Renal Dysfunction in High-Risk Patients After On-Pump and Off-Pump Coronary Artery Bypass Surgery: A Propensity Score Analysis

BACKGROUND

Cardiopulmonary bypass may be a causal factor in the development of renal impairment after cardiac surgery. When acute renal failure requiring dialysis occurs after cardiac surgery, it is associated with high mortality. We attempted to determine whether off-pump coronary artery bypass grafting surgery prevents postoperative renal dysfunction in patients at high risk for renal failure.

METHODS

Retrospective analysis identified 2,869 patients who had preexisting renal dysfunction (preoperative creatinine clearance less than 60 mL/min) and who underwent isolated coronary artery bypass grafting between 1995 and 2003. Patients who required preoperative dialysis were excluded. Propensity scores were computed to match off-pump coronary artery bypass surgery patients 3:1 with those who underwent conventional coronary artery bypass grafting surgery, and the independent predictors of postoperative renal dysfunction were determined.

RESULTS

Two thousand seven hundred eleven patients with preexisting renal dysfunction underwent conventional coronary artery bypass grafting surgery, and 158 patients underwent coronary artery bypass grafting surgery without cardiopulmonary bypass (off-pump coronary artery bypass grafting surgery group). The matched groups showed no differences in any of the preoperative or postoperative variables examined. Diabetes (odds ratio, 1.96; p = 0.01), peripheral vascular disease (odds ratio, 2.50; p < 0.001), and reduced preoperative creatinine clearance (odds ratio, 1.02; p = 0.02) were independent risk factors for the development of postoperative renal dysfunction. Off-pump coronary artery bypass grafting surgery was not associated with a decreased risk of renal dysfunction by univariate or multivariable analysis.

CONCLUSIONS

Off-pump coronary artery bypass grafting surgery did not reduce the risk of postoperative renal dysfunction in this large, unselected, sequential series of patients at high risk for renal failure after coronary artery bypass grafting surgery. Our results suggest that renal function should not be a deciding factor when determining whether or not a patient undergoes off-pump coronary artery bypass grafting surgery.

Outcomes in patients admitted for chest pain with renal failure and troponin I elevations

BACKGROUND

The significance of troponin I (TnI) elevations in patients with renal failure (RF) admitted for possible myocardial ischemia is unclear. We therefore compared outcomes in patients with and without TnI elevations based on renal function.

METHODS

Consecutive patients without ST elevation admitted for exclusion of ischemia underwent serial assessment of cardiac markers including TnI. Coronary angiography, significant disease, and revascularization were determined, and 1-year cardiac mortality and all-cause mortality were assessed. Mortality was assessed based on TnI elevations in patients with no (creatinine clearance [CrCl] > or = 60 mL/min), moderate (CrCl 30-59 mL/min), and severe (CrCl < 30 mL/min) RF.

RESULTS

Troponin I elevations were present in 17% of the 3774 consecutive patients and were significantly more frequent in patients with RF (CrCl < 30 mL/min: 26%; CrCl 30-59 mL/min: 19%; CrCl > 60 mL/min: 13%, all P < or = .01). Coronary angiography was performed significantly less frequently in patients with RF, whether TnI elevations were present. One-year all-cause mortality increased with both RF and TnI positivity (TnI [+] vs TnI [-], CrCl < 30 mL/min: 52% vs 26%; CrCl 30-59 mL/min: 21% vs 14%; CrCl > 60 mL/min: 8.9% vs 4.9%, all P < .001) . Troponin I was the most important independent predictor of mortality in the 3 RF groups (odds ratio 3.3 for CrCl < 30 mL/min, 2.2 for CrCl 30-59 mL/min, and 3.3 for CrCl > 60 mL/min).

CONCLUSIONS

Troponin I elevations identified a high-risk cohort, and its prognostic value was not diminished in patients with RF.

Creatinine clearance and risk of early mortality in patients undergoing coronary artery bypass grafting

OBJECTIVES

We sought to evaluate renal function assessed on the basis of calculated creatinine clearance as a predictor of early mortality and postoperative complications in patients undergoing coronary artery bypass grafting and to assess whether calculated creatinine clearance is superior to serum creatinine concentration in predicting early death postoperatively.

METHODS

Six thousand seven hundred eleven consecutive patients without dialysis-dependent renal insufficiency undergoing a first isolated coronary artery bypass grafting were included. Preoperative serum creatinine concentrations and creatinine clearance calculated by using the Cockroft-Gault formula were related to mortality within 30 days postoperatively.

RESULTS

There were 136 early deaths. After adjustment for age and other confounders in multivariate analyses, moderate (calculated creatinine clearance 30-60 mL/min) and severe (calculated creatinine clearance < 30 mL/min) renal insufficiency predicted early mortality (odds ratio of 2.4 [95% confidence interval, 1.2-4.8] and odds ratio of 4.8 [95% confidence interval], 1.6-13.9, respectively) compared with normal (calculated creatinine clearance > or = 90 mL/min) renal function. The area under the receiver operating characteristic curve for calculated creatinine clearance and serum creatinine concentration was 0.71 and 0.62, respectively, yielding a difference of 0.08 (P = .0004). No increased risk of mediastinitis or bleeding was observed in patients with renal insufficiency.

CONCLUSION

Moderate and severe renal insufficiency independently increase the risk of early death after coronary artery bypass grafting. Our results indicate that calculated creatinine clearance is a better predictor of early mortality postoperatively than serum creatinine concentration.

Uremic bleeding: pathophysiology and clinical risk factors

Renal insufficiency appears clinically to be associated with a bleeding tendency. This has been documented in clinical settings including as a complication of medical interventions such as surgery and also in spontaneous bleeding events at gastrointestinal and intracranial sites. The pathophysiology that underlies this tendency appears to involve platelet dysfunction and an imbalance of mediators of normal endothelial function. It is also may be complicated by the co-morbidities in this population, such as vascular disease, hypertension and anemia, and the medical interventions required to treat such co-morbidities. This article reviews the evidence, the pathophysiology and the risk factors for increased bleeding in patients with chronic renal insufficiency.

Fenoldopam Mesylate in Early Acute Tubular Necrosis: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial

BACKGROUND

Acute tubular necrosis (ATN) occurs commonly in critically ill patients and is associated with increased morbidity and mortality. Fenoldopam is a dopamine receptor alpha1-specific agonist that increases renal blood flow in patients with kidney failure. We hypothesized that administration of low-dose fenoldopam during early ATN would decrease the need for dialysis therapy and/or incidence of death at 21 days.

METHODS

We conducted a prospective, randomized, double-blind, placebo-controlled, clinical trial in 155 patients with early ATN. Patients were considered eligible for enrollment if serum creatinine level increased to 50% greater than admission levels within 24 hours and mean arterial pressure was greater than 70 mm Hg. Patients were randomly assigned to the administration of placebo or fenoldopam for 72 hours.

RESULTS

Overall, 22 of 80 patients (27.5%) in the fenoldopam group reached the primary end point compared with 29 of 75 patients (38.7%) in the placebo group (P = 0.235). This 11% absolute reduction in the primary end point was not statistically significant (P = 0.23). Similarly, there was no difference in the incidence of dialysis therapy between patients randomly assigned to fenoldopam (13 of 80 patients; 16.25%) versus the placebo group (19 of 75 patients; 25.3%; P = 0.163). Moreover, there was no statistically significant difference in 21-day mortality rates between the 2 groups (fenoldopam, 13.8% versus placebo, 25.3%; P = 0.068). In secondary analyses, fenoldopam tended to reduce the primary end point in patients without diabetes and postoperative cardiothoracic surgery patients with early ATN (fenoldopam patients without diabetes, 14 of 54 patients [25.9%] versus placebo patients without diabetes, 23 of 52 patients [44.2%]; P = 0.048) and postoperative cardiothoracic patients (6 of 34 patients [17.6%] versus 14 of 36 patients [38.8%]; P = 0.049). Conversely, fenoldopam did not improve the primary end point in patients with diabetes or those with acute renal failure from other causes. A larger multicenter trial using separate randomizations for patients with and without diabetes will be needed to determine the efficacy of fenoldopam mesylate in specific subpopulations with ATN.

CONCLUSION

Fenoldopam does not reduce the incidence of death or dialysis therapy in intensive care unit patients with early ATN.

Non-dialysis-dependent renal dysfunction and cardiac surgery-an assessment of perioperative risk factors

OBJECTIVE

In most reports, dialysis-dependent patients are known to be at increased risk for perioperative morbidity and mortality after cardiac surgical procedures.(1-7) However, the preoperative factors important for risk stratification of patients who have renal insufficiency but are not dialysis dependent are unclear. We set forth to ascertain preoperative risk factors important for predicting 2 endpoints: (1) dialysis at discharge and (2) hospital death.

DESIGN

A retrospective analysis.

SETTING

A tertiary referral center.

PATIENTS

From a database of patients undergoing cardiopulmonary bypass over a 6-year period, 150 patients were chosen for study based on their preoperative creatinine being greater than 1.5 mg/dl.

INTERVENTIONS

Routine monitoring and care of patients after their cardiac surgical procedures.

MEASUREMENTS AND MAIN RESULTS

Many preoperative, perioperative, and postoperative variables were measured. Multivariable regression was used for data analysis. There were 21 (14%) hospital deaths and 7 (5%) patients who were not on preoperative dialysis who required dialysis at discharge. Preoperative risk factors for hospital death were the patients' New York Heart Association (NYHA) class (p = 0.004) and emergency status (p = 0.005). Preoperative risk factors for dialysis at discharge were female gender (p = 0.02), emergency status of procedure (p = 0.01), and preoperative creatinine (p = 0.03).

CONCLUSIONS

These data allow for a more accurate assessment of risk stratification in this group of patients with renal insufficiency but who are not dependent on dialysis. Given the data presented here and other studies that report good outcomes for patients with renal disease after cardiac surgical procedures,(8-10) earlier operative intervention for coronary disease in this subset of patients might be warranted.

Epidemiology and risk factors for chronic kidney disease

Kidney disease is highly prevalent in the United States population and groups at high risk for increased prevalence of CKD include individuals with a family history of ESRD, diabetes, hypertension, and cardiovascular disease. Despite the increased risk of ESRD observed for blacks compared with whites, racial disparities in the prevalence of kidney disease have not been consistently demonstrated in the United States population. Although the reasons for discrepancy in risk of ESRD and CKD have not been established, clinicians should be aware that more rapid progression of CKD among blacks is a possible explanation for this observation and that closer monitoring and intensive care of risk factors associated with progressive renal injury is warranted for blacks with CKD and in other high-risk groups. Therapeutic interventions that delay or prevent progressive kidney disease are well established and incorporated into widely disseminated clinical practice guidelines. These interventions include aggressive blood pressure control with agents that block the renin-angiotensin system, reduction of dietary protein to recommended levels for the American diet, weight loss, smoking cessation, and control of hyperlipidemia. These interventions also reduce the risk of cardiovascular disease and should be regarded as essential components of care of CKD. Achieving high levels of medically appropriate care of CKD patients and reduction in risk of progression to ESRD may be delayed by barriers created by individual and regional poverty.

Evidence-based renal protection in cardiac surgery

Acute renal dysfunction is a common serious complication of cardiac surgery. Although a diversity of mechanisms exist by which the kidney can be damaged during cardiac surgery, atheroembolism, ischemia-reperfusion, and inflammation are believed to be primary contributors to perioperative renal insult. In addition, the high metabolic demands of active tubular reabsorption and the oxygen diffusion shunt characteristic of renal circulation make the kidney particularly vulnerable to ischemic injury. Remote effects of acute renal injury likely contribute to the strong association of this condition with other major postoperative morbidities and mortality and justify the search for renoprotective agents, even when dialysis is never required. Nonpharmacologic preventive strategies include procedure planning that is based on risk stratification, avoidance of nephrotoxins, and meticulous perioperative clinical care, including optimizing intravascular volume and attention to modifiable risk factors such as minimizing hemodilution. Although numerous pharmacologic interventions to prevent or treat acute renal injury have shown promise in animal models, randomized placebo-controlled clinical trials that have looked at measures of significant adverse outcomes such as death and dialysis have not confirmed a benefit.

Five year clinical effect of coronary stenting and coronary artery bypass grafting in renal insufficient patients with multivessel coronary artery disease: insights from ARTS trial

AIMS

To compare coronary stent implantation and bypass surgery for multivessel coronary disease in patients with renal insufficiency.

METHODS AND RESULTS

In the ARTS trial, 142 moderate renal insufficient patients (Ccr<60 mL/min) with multivessel coronary disease were randomly assigned to stent implantation (n=69) or CABG (n=73). At 5 years, there was no significant difference between the two groups in terms of mortality (14.5% in the stent group vs. 12.3% in the CABG group, P=0.81), or combined endpoint of death, cerebrovascular accident (CVA), or myocardial infarction (MI) (30.4% in the stent group vs. 23.3% in the CABG group, P=0.35). Among patients who survived without CVA or MI, 18.8% in the stent group underwent a second revascularization procedure when compared with 8.2% in the surgery group (P=0.08). The event-free survival at 5 years was 50.7% in the stent group and 68.5% in the surgery group (P=0.04).

CONCLUSION

At 5 years, the differences in mortality and combined incidence of death, CVA, and MI between coronary stenting and surgery did not reach statistically significant level. However, the occurrence of MACCE in the stent group was higher than in the CABG group, mainly driven by the higher incidence of repeat revascularization in the stent group.

Chronic kidney disease as cause of cardiovascular morbidity and mortality

To make an evidence-based evaluation of the relationship between kidney failure and cardiovascular risk, we reviewed the literature obtained from a PubMed search using pre-defined keywords related to both conditions and covering 18 years (1986 until end 2003). Eighty-five publications, covering 552 258 subjects, are summarized. All but three studies support a link between kidney dysfunction and cardiovascular risk. More importantly, the association is observed very early during the evolution of renal failure: an accelerated cardiovascular risk appears at varying glomerular filtration rate (GFR) cut-off values, which were >/=60 ml/min in at least 20 studies. Many studies lacked a clear definition of cardiovascular disease and/or used a single determination of serum creatinine or GFR as an index of kidney function, which is not necessarily corresponding to well-defined chronic kidney disease. In six studies, however, chronic kidney dysfunction and cardiovascular disease were well defined and the results of these confirm the impact of kidney dysfunction. It is concluded that there is an undeniable link between kidney dysfunction and cardiovascular risk and that the presence of even subtle kidney dysfunction should be considered as one of the conditions necessitating intensive prevention of this cardiovascular risk.

Association of chronic kidney disease with clinical outcomes after coronary revascularization: the Arterial Revascularization Therapies Study (ARTS)

BACKGROUND

Chronic kidney disease (CKD) is associated with adverse outcomes after coronary artery bypass graft surgery (CABG) and percutaneous coronary interventions (PCI), but it is unclear which of these revascularization strategies is associated with lower risk for morbidity and mortality in this population. In the Arterial Revascularization Therapies Study (ARTS), we compared long-term clinical outcomes after CABG or PCI with multivessel stenting in patients with CKD.

METHODS

The ARTS randomly assigned 1205 participants with and without CKD to CABG or PCI with multivessel stenting. We defined CKD as creatinine clearance < or =60 mL/min, estimated by the Cockroft-Gault equation. The primary outcome was the composite of death, myocardial infarction (MI), or stroke; and, a secondary outcome was repeat revascularization. Participants were followed for a mean of 3 years after their intervention. We evaluated whether randomization to CABG or PCI was associated with different outcomes among participants with CKD.

RESULTS

Two hundred ninety participants (25%) had CKD at entry into ARTS. One hundred fifty-one received PCI, and 139 received CABG. No difference was observed in the primary endpoint with CABG or PCI among CKD participants (adjusted Hazard Ratio [HR] CABG vs PCI = 0.93; 95% CI 0.54-1.60; P = .97). However, CABG was associated with a reduced risk for repeat revascularization (HR = 0.28; 95% CI 0.14-0.54; P < .01). Compared with participants with normal renal function, CKD was associated with a nearly 2-fold risk for the primary outcome (unadjusted HR = 1.9; 95% CI 1.4-2.7; P < .01). After multivariate adjustment, this association remained significant (HR 1.6; 95% CI 1.1-2.4).

CONCLUSIONS

In patients with multivessel CAD and CKD, treatment with CABG or PCI with multivessel stenting led to similar outcomes of death, MI, or stroke, but CABG was associated with decreased repeat revascularizations. When compared with ARTS participants with normal renal function, those with CKD had substantially elevated risk of adverse clinical outcomes after coronary revascularization.

Serum creatinine and perioperative outcome - a matched-pairs approach using computerised anaesthesia records

BACKGROUND AND OBJECTIVE

A study was designed to utilise the resources of our computerised anaesthesia record keeping system to assess the attributable effects of increased preoperative creatinine (> 1.3 mg dL(-1)) on outcome in patients undergoing non-cardiac surgery.

METHODS

This retrospective study was based on data sets of 58 458 patients recorded with a computerised anaesthesia record keeping system over a period of 4 yr at a tertiary care university hospital. Cases were defined as patients with a preoperative creatinine > 1.3 mg dL(-1); controls (creatinine < or = 1.3 mg dL(-1)) were selected and automatically matched according to several parameters (ASA physical status, high risk and urgency of surgery, age and gender) in a stepwise fashion. Main outcome measures were hospital mortality and the incidence of intraoperative cardiovascular events.

RESULTS

Three-thousand-and-twenty-eight patients (5.2%) had preoperative creatinine values > 1.3 mg dL(-1). Matching was successful for 54.5% of the cases, leading to 1649 cases (mean creatinine 3.3 +/- 2.2 mg dL(-1)) and 1649 controls (1.0 +/- 0.2 mg dL(-1)). The crude mortality rates for the cases and matched controls were 2.2% (n = 36) and 0.9% (n = 15), respectively (P = 0.003). Intraoperative cardiovascular events were found in 30.1% of the patients (n = 496) and in 28.3% of the matched controls (n = 466; P = 0.25, power = 0.46). Using logistic regression analyses a significant association between preoperative increased creatinine and hospital mortality was found (odds ratio 2.62; 95% confidence interval [1.39; 4.931).

CONCLUSIONS

An increased preoperative serum creatinine in patients undergoing non-cardiac surgery is associated with an increased perioperative risk, but not with a higher incidence of intraoperative cardiovascular events.