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

An improvement in the outcome of acute renal failure

BACKGROUND

Acute renal failure (ARF) requiring hemodialysis (HD) treatment is related to high mortality. The aim of this study was to analyze the influence of age, disease severity, and catabolism intensity on ARF outcome in patients requiring HD treatment during a 15-year period (1987-2001).

METHODS

The retrospective, single-center study included 583 patients, 428 male, 155 female, age 49+/-15 years, treated by intermittent HD using cuprophane membranes with surface area of 1.3 m2. Liano's Acute Tubular Necrosis Individual Severity Score (ATNISS) score and Hypercatabolism Depuration Score (HDS) score were calculated to estimate disease severity and catabolism intensity in ARF patients.

RESULTS

Average age of patients significantly increased during the 15-year period for more than one decade (44 to 55 years; p=0.0359), especially during the last five-year period (47+/-14.5 vs. 53+/-14.7, p=0.00015). Disease severity showed significant increase comparing periods 1992-1996 and 1997-2001 (ATNISS 0.385+/-0.197 vs. 0.437+/-0.208; p=0.00137), while catabolism intensity during these periods was similar (HDS 0.569+/-0.145 vs. 0.582+/-0.127; p=0.357). Despite the older and more severely ill population of ARF patients, mortality showed a sustained decrease during the 15-year period. Mortality in the period from 1987 to 1991 (49/83; 59%) was similar with the period 1992-1996 (chi2=0.44, p=0.5081), but significantly higher than in the period 1997-2001 (114/250; 45.6%; chi2=3.98, p = 0.0471).

CONCLUSION

The results showed an improvement in the outcome of patients with ARF requiring HD treatment, despite increasing age, disease severity, and use of bioincompatible membranes.

The prognostic value of serum creatinine on admission in fibrinolytic-eligible patients with acute myocardial infarction

BACKGROUND

Previous studies have demonstrated that impaired renal function is associated with unfavourable outcomes in patients with acute coronary syndromes and following percutaneous coronary intervention.

METHODS

We hypothesized that serum creatinine (Cr) on admission is a useful predictor of mortality in fibrinolytic-eligible patients with ST-elevation myocardial infarction (MI). Data were collected from 352 patients with ST-elevation MI, 89% of patients underwent early invasive management.

RESULTS

30-day and 6-month mortality were increased among patients with mild to moderate (Cr > 1.2-2.8 mg/dl) renal dysfunction compared to patients with normal (Cr <or= 1.2 mg/dl) renal function (3.4% vs. 16.1%, p < 0.001 and 4.5% vs. 19.5%, p < 0.001). After adjustment for previously identified correlates of mortality in a multiple logistic regression model, higher Cr on admission remained independently associated with increased mortality (30-day, OR 4.78, 95%CI 1.55-14.73, p = 0.006; 6-month, 3.82 (1.45-10.11), p = 0.007). The incidence of mortality was reduced among those patients with renal dysfunction that also underwent acute percutaneous coronary intervention [30-day, OR 0.13, 95%CI 0.02-1.06, p < 0.03; 6-month, 0.23 (0.05-1.07), p < 0.05].

CONCLUSION

Cr on admission is a strong and independent predictor of mortality in patients with ST-elevation MI. This association does not appear to be mediated by reduced fibrinolytic efficacy, or by higher reinfarction rates among patients with renal dysfunction. Cr on admission is a rapid and widely available marker to identify high-risk patients with ST-elevation MI that have additional improvements in survival when treated with percutaneous coronary intervention.

Renal protection strategies in the perioperative period

The development of acute renal failure (ARF) in the perioperative period continues to be a vexing condition associated with high morbidity and mortality rates which have been unchanged for several decades. In this article I briefly review recent research categorizing pathogenesis of ARF and mechanisms of recovery. Once ARF is established, its maintenance phase is dependent on several mechanisms that interact with cellular integrity. The main focus of the article is on assessing clinical and experimental interventions to prevent ARF. Unfortunately, existing pharmacological and other interventions show a rather limited efficacy in preventing ARF.

Pre-existing renal failure doubles 30-day mortality after heart transplantation

BACKGROUND

Survival after cardiac transplantation has not changed over the last 10 years. Our objective was to identify risk factors for 30-day mortality after cardiac transplantation with particular reference to focusing on the impact of pre-existing renal dysfunction.

METHODS

We analyzed the data of all 1,180 patients who received a first heart transplant in the 8 adult transplant centers in the United Kingdom between April 1996 and March 2002 using the UK Cardiothoracic Transplant Audit database. Renal function at registration and transplantation was determined by calculation of creatinine clearance (CrCl) according to the Cockcroft-Gault formula.

RESULTS

Multivariate analysis showed that ventilator dependence pre-transplantation and cold ischemia time >4 hours had the highest association with 30-day mortality, followed by CrCl </=50 ml/min. Patients with a CrCl </=50 ml/min on day of transplantation had a significantly higher 30-day mortality compared to patients with CrCl >50 ml/min (19.7% vs 9.5%; p < 0.01). The change in CrCl between registration and transplantation was not related to mean CrCl or waiting time. In 67 of the patients with a CrCl >50 ml/min at registration, CrCl was reduced to </=50 ml/min on day of transplantation (30-day mortality 16.7%).

CONCLUSIONS

Pre-operative CrCl </=50 ml/min doubles the risk of death within 30 days after cardiac transplantation. Patients considered for cardiac transplantation should undergo regular measurement of renal function so that a more accurate risk-benefit assessment can be made.

Does Off-Pump Coronary Artery Bypass Reduce the Incidence of Clinically Evident Renal Dysfunction After Multivessel Myocardial Revascularization?

In this prospective, observational trial, we determined whether off-pump coronary artery bypass (OPCAB) was associated with less postoperative renal dysfunction (RD) compared with coronary bypass surgery with cardiopulmonary bypass (CABG). All patients undergoing primary, isolated coronary surgery at our institution in the year 2000 participated. Data collected on each patient included demographics, preoperative risk factors for RD, perioperative events, and serum creatinine concentrations from date of admission until discharge or death. The criteria for RD was both a >or=50% increase from preoperative creatinine and an absolute postoperative creatinine >or=2.0 mg/dL (177 microM). Student's t-test or the Fisher's exact test was used to compare groups. Stepwise multiple logistic regression identified determinants of RD; P < 0.05 significant. The CABG group (n = 119) differed from the OPCAB group (n = 220) with respect to age (64 +/- 13 versus 67 +/- 10 yr, P = 0.0074) and number of distal grafts (median 4 versus 3, P = 0.0003). Type of operation did not associate with the presence of postoperative RD: 18 (8.2%) of 220 OPCAB patients versus 12 (10%) of 119 CABG patients (P = 0.55). Our data suggest that choice of operative technique (OPCAB versus CABG) is not associated with reduced renal morbidity.

Impact of renal insufficiency on short- and long-term outcomes after cardiac surgery

BACKGROUND

Renal insufficiency is highly prevalent in North America and has been established as a nontraditional risk factor for cardiovascular disease. Cardiovascular disease remains the primary cause of mortality in the general population and is often treated with coronary artery bypass surgery (CABG). This population-based study aimed to determine the risk of nondialysis dependent renal insufficiency (RI) on the long-term outcomes of patients who undergo CABG.

METHODS

Prospectively collected data from 26,506 patients were abstracted from the Cardiac Care Network database from 9 revascularization hospitals in Ontario, Canada. Multivariate regression analysis examined associations between preoperative RI and inhospital, 30-day, and 1-year mortality according to 3 levels of serum creatinine: <120 micromol/L (normal), 120 to 180 micromol/L (mild RI), and >180 micromil/L (moderate-severe RI) and 5 levels of creatinine clearance (Cockcroft-Gault): >100 mL/min (normal), 80 to 99 mL/min (mild impairment), 60 to 79 mL/min (mild-moderate impairment), 40 to 59 mL/min (moderate impairment), and <40 mL/min (severe impairment).

RESULTS

The overall inhospital, 30-day, and 1-year mortality rates were 1.90%, 2.0%, and 4.5%, respectively. Patients with RI had greater overall comorbidity. After adjustment for confounding factors, RI was associated with the greater risk of both 30-day (odds ratio 3.7, 95% CI 2.3-5.8, P <.0001) and 1-year mortality (odds ratio 4.6, 95% CI 3.3-6.4, P <.0001).

CONCLUSION

Preoperative renal impairment should be recognized as a significant risk factor for mortality after CABG. A trend of increasing risk with severity of renal impairment was demonstrated for both 30-day and 1-year mortality in this large, population-based study.

Continuous Renal Replacement Therapy after Cardiac Surgery

BACKGROUND/AIMS

To evaluate the outcome of patients who require continuous renal replacement therapy (CRRT) following cardiac surgery.

METHODS

All patients who received CRRT after cardiac surgery over more than 4 years at the Surgical Intensive Care Unit of the Montreal Heart Institute were reviewed. Among 5,564 consecutive patients, 85 underwent CRRT postoperatively.

RESULTS

The mean delay between surgery and CRRT initiation was 5 days, and the duration of CRRT was 9 days, without a difference between survivors and non-survivors. Delivered clearances with CRRT were estimated at 25-28 ml/min (approximately 40 liters/day), 29-32 ml/min (approximately 46 liters/day) and 17 ml/min (approximately 25 liters/day) for continuous veno-venous hemofiltration, continuous veno-venous hemodiafiltration and continuous veno-venous hemodialysis, respectively. In-hospital mortality was 43.5%. No difference in mortality was observed between patients with normal renal function at baseline and those with pre-operative renal dysfunction. Mortality was 33.3% after a coronary artery bypass graft (CABG), 57.1% after CABG and valve surgery, 60% after valve surgery, and 72.7% for redo-CABG or redo-valve surgery. 79% of survivors and 86% of non-survivors had received a cardiopulmonary bypass (p = NS). The Simplified Acute Physiology Score II upon intensive care unit (ICU) admission and the requirement of an intra-aortic balloon pump were higher in non-survivors (p < 0.05). The mean length of ICU and hospital stay was 27.4 and 34.2 days for survivors and 17.9 and 22.3 days for non-survivors, respectively (p < 0.05).

CONCLUSIONS

Renal impairment is relatively common after cardiac surgery. The mortality of patients who required CRRT after cardiac surgery was 43.5% and was particularly influenced by the type of surgery.

Neurological Complications After Coronary Artery Bypass Grafting Related to the Performance of Cardiopulmonary Bypass

STUDY OBJECTIVES

Neurologic disorders belong among the most serious complications of cardiac surgery. We tested the hypothesis that combinations of hemodynamic events from apparently normal cardiopulmonary bypass (CPB) procedures are related to the development of postoperative neurologic complications and affect the impact of common clinical risk factors.

DESIGN

Retrospective study.

SETTING

Cardiothoracic surgery department in a university hospital.

METHODS AND PATIENTS

A multivariate statistical procedure (ie, cluster analysis) was applied to a data set of automatically recorded perfusions from 1,395 patients who had undergone coronary artery bypass grafting. One-way analysis of variance was used to select five parameters with the strongest significant correlation to postoperative neurologic complications for further cluster analysis. The dependencies in the clusters were tested against common clinical risk factors. To our knowledge, this is the first study of its kind.

RESULTS

The following five parameters emerged for cluster analysis: mean arterial pressure (MAP); dispersion of MAP; dispersion of systemic vascular resistance; dispersion of arterial pulse pressure; and the maximum value of mixed venous saturation. Using these parameters, we found four clusters that were significantly different by CPB performance (first cluster, 389 patients; second cluster, 431 patients; third cluster; and fourth cluster, 229 patients). The frequency of postoperative neurologic complications was 0.3% in the first cluster and increased to 3.9% in the fourth cluster. Importantly, the impact of common clinical risk factors for postoperative neurologic complications was affected by the performance of the CPB procedure. For example, the frequency of neurologic complications among patients with cerebrovascular disease in their medical history was 22% in the fourth cluster, whereas it was zero in the second cluster.

CONCLUSIONS

This study shows that apparently normal CPB procedures affect the impact of common clinical risk factors on postoperative neurologic complications. Patients who underwent CPB procedures with large fluctuations in hemodynamic parameters particularly showed an increased risk for the development of postoperative neurologic complications.

Renal insufficiency and mortality from acute coronary syndromes

BACKGROUND

Although there is accumulating evidence that renal insufficiency is an independent risk factor for mortality after acute myocardial infarction (AMI), it is not known whether renal dysfunction is associated with an increased mortality rate after a broad range of acute coronary syndromes, including unstable angina.

METHODS

We examined consecutive patients from 24 Veterans Affairs hospitals with confirmed AMI or unstable angina between March 1998 and February 1999, who were categorized into groups according to estimated glomerular filtration rate (GFR). Multivariable regression was used to assess the independent association between GFR and the 7-month mortality rate, adjusting for differences in patient characteristics and treatment.

RESULTS

Of the 2706 patients, 436 (16%) had normal renal function (GFR >90 mL/min/1.73 m(2)), 1169 (43%) had mild renal insufficiency (GFR 60-89 mL/min/1.73 m(2)), 864 (32%) had moderate renal insufficiency (GFR 30-59 mL/min/1.73 m(2)), and 237 (9%) had severe renal insufficiency (GFR <30 mL/min/1.73 m(2)). Patients with renal insufficiency were less likely to undergo coronary angiography or to receive aspirin or beta-blockers at discharge. In multivariable models, renal insufficiency was associated with a higher odds of death (mild renal insufficiency: odds ratio [OR] = 1.76; 95% CI, 0.93-3.33; moderate renal insufficiency: OR = 2.72; 95% CI, 1.43-5.15; and severe renal insufficiency: OR = 6.18; 95% CI, 3.09-12.36; all compared with normal renal function). The associations between renal insufficiency and mortality rate were similar in both the AMI and unstable angina subgroups (P value for interaction =.45).

CONCLUSIONS

Renal insufficiency is common and is associated with higher risks for death in patients with a broad range of ACS at presentation. Future efforts should be dedicated to determining whether more aggressive treatment will optimize outcomes in this patient population.

Influence of renal insufficiency on limb loss and mortality after initial lower extremity surgical revascularization

OBJECTIVE

Limb loss after lower extremity surgical revascularization occurs relatively frequently in patients receiving dialysis. The goal of the present study was to determine whether patients with milder degrees of renal insufficiency are also at risk for this complication.

MATERIAL AND METHODS

This cohort study was carried out at the Department of Veterans Affairs (VA). The study sample consisted of 9932 patients undergoing an initial surgical revascularization procedure between October 1, 1995, and September 30, 2000, recorded by the VA National Surgical Quality Improvement Program (NSQIP). We examined the occurrence of major amputation within 1 year of lower extremity surgical revascularization by level of renal function.

RESULTS

Eleven percent of study patients underwent major lower extremity amputation within 1 year of NSQIP-documented lower extremity revascularization surgery: 10% (739 of 7335) of patients with normal renal function, 11% (251 of 2210) of patients with moderately reduced renal function, 12% (24 of 205) of patients with severe renal insufficiency, and 29% (53 of 182) of patients receiving dialysis. After adjustment for demographic characteristics and comorbid conditions, only patients receiving dialysis were at significantly increased risk for amputation, compared with patients with normal renal function (odds ratio, 2.46; 95% confidence interval, 1.74-3.47; P<.001). Compared with all other veterans undergoing bypass procedures, patients receiving dialysis were more likely to have a wound infection; a diagnostic code for lower extremity gangrene, infection, or ischemic ulceration; an elevated white blood cell count; and preoperative sepsis at the time of initial revascularization. In addition, they were more likely to have a preoperative hospital stay longer than 1 week, undergo concurrent minor amputation, and undergo an outflow (vs inflow) procedure.

CONCLUSION

Only patients receiving dialysis, and not patients with milder degrees of renal insufficiency, appear to be at higher risk for limb loss after revascularization, compared with patients with normal renal function. Further studies are needed to determine why patients receiving dialysis are at a singularly increased risk for limb loss after lower extremity revascularization and whether their more frequent presentation with limb-threatening infection at the time of revascularization reflects late presentation for surgery or a more rapid course of peripheral arterial disease in this patient group.

Calcium antagonists are associated with reduced mortality after cardiac surgery: a propensity analysis

OBJECTIVES

Observational studies have questioned the effectiveness of perioperative calcium channel blockers but failed to correct for selection biases. We therefore performed a prospective observational cohort study of the effects of calcium channel blockers on cardiac surgical mortality. A propensity score technique was used for risk adjustment.

METHODS

We identified 6619 patients who underwent nontransplant cardiac surgery at the Toronto General Hospital (Toronto, Ontario, Canada) between May 1999 and December 2001. Propensity scores for calcium channel blocker use were constructed for the entire sample and for the subgroup (n = 5222) that underwent coronary artery bypass grafting. The calcium channel blocker adjusted odds ratio for in-hospital mortality after cardiac surgery was determined by using multiple logistic regression and propensity matched-pairs analyses. A subgroup analysis was performed for patients who underwent coronary artery bypass grafting: the calcium channel blocker adjusted odds ratio for mortality was determined by using propensity score matched-pairs analyses.

RESULTS

Calcium channel blockers were associated with significantly reduced cardiac surgical mortality after adjustment with both multiple logistic regression (odds ratio, 0.56; 95% confidence interval, 0.33-0.94; P =.028) and propensity score matched-pairs analyses (odds ratio, 0.56; 95% confidence interval, 0.32-0.98; P =.042). Calcium channel blockers were also associated with reduced mortality (odds ratio, 0.48; 95% confidence interval, 0.23-0.98; P =.044) among patients who underwent coronary artery bypass grafting.

CONCLUSIONS

After adjustment for baseline differences, calcium channel blockers were associated with significantly reduced mortality after cardiac surgery. This benefit also extends to the subgroup that underwent coronary artery bypass grafting. A large randomized controlled trial of perioperative calcium channel blockers is therefore warranted.

Perioperative management of patients with chronic kidney disease or ESRD

The perioperative management of patients with chronic kidney disease (CKD) or dialysis-dependent end-stage renal disease (ESRD) is complicated by both the underlying renal dysfunction, with associated disturbances of fluid and electrolyte homeostasis and altered drug clearance, and the presence of associated co-morbid conditions, including diabetes mellitus, chronic hypertension and cardiovascular and cerebrovascular disease. The impact of CKD on fluid and electrolyte management, haematological and cardiovascular complications and drug management in the perioperative period are reviewed. Special issues related to the management of haemodialysis and peritoneal dialysis patients in the perioperative period are also reviewed.

Association of creatinine and creatinine clearance on presentation in acute myocardial infarction with subsequent mortality

OBJECTIVES

We hypothesized that impaired renal function would also be associated with poorer clinical outcomes among patients with ST-segment elevation myocardial infarction (STEMI) treated with fibrinolysis.

BACKGROUND

Previous studies have demonstrated that impaired renal function is associated with poorer clinical outcomes in the setting of unstable angina and non-STEMI and after percutaneous coronary intervention.

METHODS

Data were drawn from the Thrombolysis In Myocardial Infarction (TIMI)-10, TIMI-14, and Intravenous nPA for the Treatment of Infarcting Myocardium Early (InTIME-II) trials.

RESULTS

Within each TIMI risk score (TRS) for STEMI category (0 to 2, 3 to 4, >/=5), 30-day mortality increased stepwise among patients with normal (creatinine [Cr] </=1.2 mg/dl), mildly (Cr >1.2 to 2 mg/dl), and severely (Cr >2.0 mg/dl) impaired renal function (p < 0.001) and in patients with normal (creatinine clearance [CrCl] >/=90 ml/min), mildly (60 to <90 ml/min), moderately (30 to <60 ml/min), and severely (<30 ml/min) impaired CrCl (p < 0.001). Impaired renal function was associated with increased mortality after adjusting for previously identified correlates of mortality (using Cr: odds ratio [OR] for mild impairment 1.52, 95% confidence interval [CI] 1.30 to 1.77, p < 0.001; OR for severe impairment 3.73, 95% CI 2.55 to 5.45, p < 0.001; using CrCl: OR for mild impairment 1.38, 95% CI 1.10 to 1.73, p = 0.006; OR for moderate impairment 2.06, 95% CI 1.59 to 2.66, p < 0.001; OR for severe impairment 3.81, 95% CI 2.57 to 5.65, p < 0.001).

CONCLUSIONS

In the setting of STEMI, elevated Cr and/or impaired CrCl on presentation is associated with increased mortality, independent of other conventional risk factors and TRS. This association does not appear to be mediated by reduced fibrinolytic efficacy among patients with impaired renal function or by the presence of congestive heart failure on presentation.

Impact of renal disease in cardiovascular surgery: emphasis on the African-American patient

Cardiovascular disease remains a significant source of morbidity and mortality for patients with kidney disease. Coincident with the development of chronic renal failure, patients typically manifest a systemic vasculopathy often involving the cardiovascular system. The renal failure patient is also plagued by multiple comorbid conditions that may adversely affect cardiovascular outcomes. Consistent with the national trend of increasing numbers of patients requiring renal replacement therapy (RRT), patients requiring invasive cardiovascular procedures are also on the incline. The morbidity and mortality related to these procedures has remained high despite significant advances in delivery and maintenance of care. Is the African-American patient with renal failure unique in terms of cardiovascular morbidity and mortality? Numerous studies have documented racial differences in access to invasive cardiovascular procedures, even after controlling for multiple physiologic risk factors and socioeconomic and sociocultural factors. Studies have also shown higher morbidity and lower survival for African-American patients after cardiac procedures. In this high-risk population these same issues perhaps would persist. The following paper will examine the current status of cardiovascular disease in the renal failure patient with emphasis on the African-American patient population.

Predictors of prolonged ICU stay after on-pump versus off-pump coronary artery bypass grafting

OBJECTIVE

To define predictors for prolonged ICU stay in order to improve patient outcome and reduce costs.

PATIENTS AND METHODS

Prospective data on 10,759 patients undergoing coronary artery bypass grafting with and without use of cardiopulmonary bypass (coronary artery bypass grafting, CABG; n =8,917; off-pump coronary artery bypass grafting, OPCAB; n =765; minimally invasive direct coronary artery bypass grafting, MIDCAB; n =1,077) between April 1996 and August 2001 were subjected to univariate and, consecutively, to multivariate logistic regression analysis. Prolonged ICU stay was defined as intensive care treatment for three postoperative days and longer.

MEASUREMENTS AND RESULTS

Mean duration of ICU stay was 3.8+/-6.9 days; overall prevalence of prolonged ICU stay was 37.1%. The hospital mortality was 3.5% (ICU > or =3 days: 5.9%; ICU <3 days: 2.0%). Out of 39 selected pre- and intraoperative patient- and treatment-related variables, by univariate analysis, 32 variables having a high association with prolonged ICU stay were identified. Using a stepwise logistic regression model, 20 variables were shown to be independent predictors for prolonged ICU stay. Both OPCAB and MIDCAB surgery were identified as having a significantly lower association with prolonged ICU stay.

CONCLUSION

As prolonged ICU stay is associated with poor patient outcome and increased costs it is of utmost importance to identify patients at a high risk for prolonged ICU stay. More frequent off-pump CABG may optimize patient outcome.

Chronic kidney disease, mortality, and treatment strategies among patients with clinically significant coronary artery disease

Cardiovascular disease is an important cause of mortality among patients with chronic kidney disease (CKD). This study describes associations between CKD, cardiac revascularization strategies, and mortality among patients with CKD and cardiovascular disease. All patients undergoing cardiac catheterization at Duke University Medical Center (1995 to 2000) with documented stenosis > or =75% of at least one coronary artery and available creatinine data were included. CKD was staged using creatinine clearance (CrCl) derived from the Cockcroft-Gault formula (normal, > or = 90 ml/min; mild, 60 to 89 ml/min; moderate, 30 to 59 ml/min; severe, 15 to 29 ml/min). Cox proportional-hazard regression estimated the relationship between clinical variables, including CrCl and percutaneous coronary artery intervention (PCI), coronary artery bypass grafting (CABG), medical management, and patient survival. There were 4584 patients included, and 24% had CrCl <60 ml/min. Each 10-ml/min decrement in CrCl was associated with an increase in mortality (hazard ratio, 1.14; P < 0.0001). CABG was associated with a survival benefit among patients with both normal renal function and patients with CKD compared with medical management. In patients with normal renal function, CABG was not associated with survival benefit over PCI. However, in patients with CKD, CABG was associated with improved survival. PCI was associated with a survival benefit compared with medical management among patients with normal, mildly, and moderately impaired renal function. Among patients with severe CKD, PCI was not associated with improved survival. CABG is associated with greater mortality reduction than PCI in severe CKD.

Impact of renal insufficiency on short-term morbidity and mortality after lower extremity revascularization: data from the Department of Veterans Affairs' National Surgical Quality Improvement Program

Few data are available on the impact of renal insufficiency on short-term operative outcomes after lower extremity surgical revascularization. We used prospectively collected data from the Department of Veterans Affairs' National Surgical Quality Improvement Program (NSQIP) to explore the association with renal dysfunction of adverse outcomes occurring within 30 d of lower extremity surgical revascularization in a cohort of all patients undergoing at least one lower extremity surgical revascularization from 1/1/94 to 9/30/01 (n = 18,217). Even moderate renal insufficiency (estimated GFR 30-59cc/min/1.73m(2)) was associated with an increased incidence of postoperative death (adjusted odds ratio (OR) 1.44, 95% confidence interval (CI), 1.17 to 1.77, P = 0.001), cardiac arrest (OR 1.43, CI 1.09 to 1.88, P = 0.011), myocardial infarction (OR 1.68, 1.39 to 2.16, P < 0.001), unplanned intubation (OR 1.69, CI 1.39 to 2.07, P < 0.001) and prolonged intubation (OR 1.57, CI 1.28 to 1.94, P < 0.001) within 30 d of lower extremity revascularization. However, the incidence of wound infection and graft failure requiring return to the operating room did not appear to be substantially higher in this group. Our data also show that patients with renal insufficiency undergoing revascularization were more likely to require distal procedures and to present with limb-threatening infection compared to those with normal renal function. Efforts to improve pre-and post-operative care in patients with renal insufficiency undergoing lower extremity revascularization should take into account the increased incidence of postoperative death and cardiopulmonary complications in this group in addition to more traditional concerns about operative site complications. Further studies are needed to explore reasons for the higher rate of limb-threatening infection in patients with renal insufficiency undergoing revascularization.

Renal insufficiency as a predictor of cardiovascular outcomes and mortality in elderly individuals

OBJECTIVES

This study was designed to evaluate the relationship between elevated creatinine levels and cardiovascular events.

BACKGROUND

End-stage renal disease is associated with high cardiovascular morbidity and mortality. The association of mild to moderate renal insufficiency with cardiovascular outcomes remains unclear.

METHODS

We analyzed data from the Cardiovascular Health Study, a prospective population-based study of subjects, aged >65 years, who had a serum creatinine measured at baseline (n = 5,808) and were followed for a median of 7.3 years. Proportional hazards models were used to examine the association of creatinine to all-cause mortality and incident cardiovascular mortality and morbidity. Renal insufficiency was defined as a creatinine level > or =1.5 mg/dl in men or > or =1.3 mg/dl in women.

RESULTS

An elevated creatinine level was present in 648 (11.2%) participants. Subjects with elevated creatinine had higher overall (76.7 vs. 29.5/1,000 years, p < 0.001) and cardiovascular (35.8 vs. 13.0/1,000 years, p < 0.001) mortality than those with normal creatinine levels. They were more likely to develop cardiovascular disease (54.0 vs. 31.8/1,000 years, p < 0.001), stroke (21.1 vs. 11.9/1,000 years, p < 0.001), congestive heart failure (38.7 vs. 17/1,000 years, p < 0.001), and symptomatic peripheral vascular disease (10.6 vs. 3.5/1,000 years, p < 0.001). After adjusting for cardiovascular risk factors and subclinical disease measures, elevated creatinine remained a significant predictor of all-cause and cardiovascular mortality, total cardiovascular disease (CVD), claudication, and congestive heart failure (CHF). A linear increase in risk was observed with increasing creatinine.

CONCLUSIONS

Elevated creatinine levels are common in older adults and are associated with increased risk of mortality, CVD, and CHF. The increased risk is apparent early in renal disease.

Factors affecting transfusion of fresh frozen plasma, platelets, and red blood cells during elective coronary artery bypass graft surgery

CONTEXT

The ability to predict the use of blood components during surgery will improve the blood bank's ability to provide efficient service.

OBJECTIVE

Develop prediction models using preoperative risk factors to assess blood component usage during elective coronary artery bypass graft surgery (CABG).

DESIGN

Eighty-three preoperative, multidimensional risk variables were evaluated for patients undergoing elective CABG-only surgery.

MAIN OUTCOMES MEASURES

The study endpoints included transfusion of fresh frozen plasma (FFP), platelets, and red blood cells (RBC). Multivariate logistic regression models were built to assess the predictors related to each of these endpoints.

SETTING

Department of Veterans Affairs (VA) health care system.

PATIENTS

Records for 3034 patients undergoing elective CABG-only procedures; 1033 patients received a blood component transfusion during CABG.

RESULTS

Previous heart surgery and decreased ejection fraction were significant predictors of transfusion for all blood components. Platelet count was predictive of platelet transfusion and FFP utilization. Baseline hemoglobin was a predictive factor for more than 2 units of RBC. Some significant hospital variation was noted beyond that predicted by patient risk factors alone.

CONCLUSIONS

Prediction models based on preoperative variables may facilitate blood component management for patients undergoing elective CABG. Algorithms are available to predict transfusion resources to assist blood banks in improving responsiveness to clinical needs. Predictors for use of each blood component may be identified prior to elective CABG for VA patients.

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.

Stroke after cardiac surgery: a risk factor analysis of 16,184 consecutive adult patients

BACKGROUND

Stroke remains a devastating complication after cardiac surgical procedures despite advances in perioperative monitoring and management. The purpose of this study was to determine the predictors of stroke in a large, contemporary cardiac surgery population.

METHODS

Prospective data on 16,184 consecutive patients undergoing cardiac surgery (coronary artery bypass grafting [CABG], n = 8,917; beating heart CABG, n = 1,842; aortic valve surgery, n = 1,830; mitral valve surgery, n = 708; double or triple valve surgery, n = 381; CABG and valve surgery, n = 2,506) between April 1996 and August 2001 were subjected to univariate and multivariate analysis. Stroke was defined as any new permanent (manifest stroke) or temporary neurologic deficit or deterioration (transient ischemic attack or prolonged reversible ischemic neurologic deficit) and was confirmed by computed tomography or magnetic resonance imaging whenever possible.

RESULTS

Overall incidence of stroke was 4.6% and varied between surgical procedures (CABG 3.8%; beating-heart CABG 1.9%; aortic valve surgery 4.8%; mitral valve surgery 8.8%; double or triple valve surgery 9.7%; CABG and valve surgery 7.4%). Of 63 patient-specific and treatment variables, 54 were found to have a significant univariate association with postoperative stroke. Multivariable analysis revealed 10 variables that were independent predictors of stroke: history of cerebrovascular disease, peripheral vascular disease, diabetes, hypertension, previous cardiac surgery, preoperative infection, urgent operation, CPB time more than 2 hours, need for intraoperative hemofiltration, and high transfusion requirement. Beating heart CABG was associated with a lower incidence of stroke in this multivariable analysis.

CONCLUSIONS

Identification of predictors for stroke is important for understanding the pathogenesis of this devastating complication as well as for developing preventative strategies. Although retrospective analyses can be subject to selection bias we believe beating heart CABG is associated with a lower incidence of stroke and may therefore improve patient outcomes.

Chronic kidney disease as a risk factor for bleeding complications after coronary artery bypass surgery

BACKGROUND

The aim of the study is to define the role of chronic kidney disease (CKD) as a risk factor for postoperative bleeding in patients undergoing coronary artery bypass graft (CABG) surgery.

METHODS

This is a retrospective cohort study of 238 consecutive patients who underwent isolated CABG surgery. Patients were followed up for the event of a significant bleed, defined as administration of either three or greater units of packed red blood cells, three or greater units of platelets, three or greater units of fresh frozen plasma, or any cryoprecipitate within 72 hours after a CABG procedure or undergoing a surgical revision for bleeding. Glomerular filtration rate (GFR) at baseline was calculated using the Cockroft-Gault formula. A final multiple logistic regression model was selected from a large set of presurgical and intraoperative covariates by using backward elimination (P > 0.20).

RESULTS

After controlling for age, sex, elective versus emergent surgery, intraoperative activated clotting time, serum albumin level, extracorporeal bypass time, and baseline hematocrit, we found that even mild levels of renal impairment were associated with increased risk for postoperative bleeding: patients with a GFR of 40 mL/min or less had six times the odds of postoperative bleeding than patients with a GFR greater than 100 mL/min (odds ratio [OR], 6.51; 95% confidence interval [CI], 1.87 to 22.66); those with a GFR of 41 to 60 mL/min had nearly four times the risk (OR, 3.87; 95% CI, 1.21 to 12.35). Even patients with mild CKD at a GFR of 61 to 80 mL/min were at an elevated risk (OR, 2.11); however, the 95% CI of 0.79 to 5.64 included the null value. Similar results were found when using the cruder Kidney Disease Outcomes Quality Initiative classification of CKD.

CONCLUSION

CKD is associated with risk for postoperative bleeding in patients undergoing CABG surgery, not only at more advanced stages, but probably at relatively mild levels of renal impairment, as well.

Treatment effects of eptifibatide in planned coronary stent implantation in patients with chronic kidney disease (ESPRIT Trial)

The role of platelet glycoprotein IIb/IIIa inhibitor therapy in patients with mild renal impairment is not well characterized. Our objective was to explore the associations of creatinine clearance (CrCl) with outcomes in a trial of eptifibatide therapy in patients who underwent percutaneous coronary intervention (PCI). We analyzed 48-hour and 30-day outcomes of patients enrolled in the Enhanced Suppression of the Platelet IIb/IIIa Receptor with Integrilin Therapy (ESPRIT) trial. Patients were randomly assigned to placebo or eptifibatide as an adjunct to stent implantation (1,755 with CrCl > or =60 ml/min and 289 with CrCl <60 ml/min). CrCl was calculated using the Cockcroft and Gault formula, and the associations of CrCl with outcomes were evaluated using logistic regression models. Patients with CrCl <60 ml/min were more likely to be older, women, hypertensive, and have a history of coronary artery bypass surgery, stroke, or peripheral vascular disease. The interaction of eptifibatide with CrCl had borderline significance for the 30-day outcome (p = 0.109). Treatment effect trended toward a greater magnitude in patients with lower CrCl (60 ml/min) (odds ratio 0.53, confidence interval 0.34 to 0.83) compared with those with higher CrCl (90 ml/min) (odds ratio 0.68, confidence interval 0.49 to 0.94). An accompanying increase in bleeding risk also was not apparent with lower CrCl. The treatment effect of eptifibatide is realized regardless of renal function and trends toward being greater in patients with mild renal impairment.

Perioperative care of the patient with renal failure

Preventing postoperative ARF, especially in subjects with pre-existing chronic kidney disease, and caring for ESRD patients undergoing surgery are challenging and best accomplished by a team comprised of primary care physician, nephrologist, cardiologist, surgeon, anesthesiologist, endocrinologist, and nutritionist. Elimination of risk factors for ARF whenever possible, as well as early diagnosis, may improve the outcome of this devastating illness. Drugs capable of preventing or changing the course of postoperative ARF may be available soon. For uremic patients, a comprehensive approach is necessary to minimize morbidity and mortality imposed by numerous comorbid conditions.

The impact of ethnicity on outcomes following coronary artery bypass graft surgery in the Veterans Health Administration

OBJECTIVES

We evaluated the effect of African American (AA) and Hispanic American (HA) ethnicity on mortality and complications following coronary artery bypass graft (CABG) surgery in the Veterans Health Administration (VHA).

BACKGROUND

Few studies have examined the impact of ethnicity on outcomes following cardiovascular procedures.

METHODS

This study included all 29,333 Caucasian, 2,570 AA, and 1,525 HA patients who underwent CABG surgery at any one of the 43 VHA cardiac surgery centers from January 1995 through March 2001. We evaluated the relationship between ethnicity (AA vs. Caucasian and HA vs. Caucasian) and 30-day mortality, 6-month mortality, and 30-day complications, adjusting for a wide array of demographic, cardiac, and noncardiac variables.

RESULTS

After adjustment for baseline characteristics, AA and Caucasian patients had similar 30-day (AA/Caucasian odds ratio [OR] 1.07; 95% confidence interval [CI] 0.84 to 1.35; p = 0.59) and 6-month mortality risk (AA/Caucasian OR 1.10; 95% CI 0.91 to 1.34; p = 0.31). However, among patients with low surgical risk, AA ethnicity was associated with higher mortality (OR 1.52, CI 1.10 to 2.11, p = 0.01), and AA patients were more likely to experience complications following surgery (OR 1.28; 95% CI 1.14 to 1.45; p < 0.01). In contrast, HA patients had lower 30-day (HA/Caucasian OR 0.70; 95% CI 0.49 to 0.98; p = 0.04) and 6-month mortality risk (HA/Caucasian OR 0.66; 95% CI 0.50 to 0.88; p < 0.01) than Caucasian patients.

CONCLUSIONS

Ethnicity does not appear to be a strong risk factor for adverse outcomes following CABG surgery in the VHA. Future studies are needed to determine why AA patients have more complications, but ethnicity should not affect the decision to offer the operation.

Prognostic implications of abnormalities in renal function in patients with acute coronary syndromes

BACKGROUND

Outcomes in patients with mild to moderate renal function (RF) abnormalities presenting with acute coronary syndromes (ACS) are not well defined.

METHODS AND RESULTS

A convenience sample of 4 ACS trial databases including all enrolled patients was assessed to determine 30- and 180-day outcomes. The 4 trials were Global Use of Strategies to Open Occluded Coronary Arteries (GUSTO) IIb, GUSTO-III, Platelet Glycoprotein IIb/IIIa in Unstable Angina: Receptor Suppression Using Integrilin Therapy (PURSUIT), and Platelet IIb/IIIa Antagonism for the Reduction of Acute coronary syndrome events in a Global Organization Network (PARAGON-A). Patients were stratified into ST-segment elevation (STE) and non-ST-segment elevation (NSE) groups and by the presence or absence of abnormal RF (creatinine clearance <70 mL/min). In the STE group, 7670 of 18 621 patients (41%) had abnormal RF. In the NSE group, 8152 of 19 304 (42%) had abnormal RF. Patients with abnormal RF were older, more often female, and more likely to have adverse baseline characteristics. They had higher mortality and higher mortality/nonfatal myocardial infarction (MI) at both 30 and 180 days, regardless of ST-segment status. Creatinine clearance was independently associated with risk of mortality (hazard ratio 0.79 in the STE group and 0.81 in the NSE group) and with risk of mortality/MI (hazard ratio 0.93) in the NSE group at 180 days.

CONCLUSIONS

Patients presenting with ACS frequently have abnormal RF. Abnormal RF is a marker of adverse baseline clinical characteristics and is independently associated with increased risk of death and death/MI.

Modest serum creatinine elevation affects adverse outcome after general surgery

BACKGROUND

Modest preoperative serum creatinine elevation (1.5 to 3.0 mg/dL) has been recently shown to be independently associated with morbidity and mortality after cardiac surgery. It is important to know if this association can be applied more broadly to general surgery cases.

METHODS

Multivariable logistic regression analyses of 46 risk variables in 49,081 cases from the Veterans Affairs National Surgical Quality Improvement Program, undergoing major general surgery from 10/1/96 through 9/30/98.

RESULTS

Thirty day mortality and several cardiac, respiratory, infectious and hemorrhagic morbidities were significantly (P < 0.001) higher in patients with a serum creatinine>1.5 mg/dL. With multivariable analysis, the adjusted odds ratio for mortality for patients with a serum creatinine of 1.5 to 3.0 mg/dL was 1.44 [95% confidence interval (95% CI) 1.22 to 1.71] and for creatinine>3.0 mg/dL was 1.93 (95% CI 1.51 to 2.46). The adjusted odds ratio for morbidity (one or more postoperative complications) for patients with a serum creatinine of 1.5 to 3.0 mg/dL was 1.18 (95% CI 1.06 to 1.32) and for creatinine>3.0 mg/dL was 1.19 (95% CI 0.99 to 1.43). Further stratification and recursive partitioning of creatinine levels revealed that a serum creatinine level>1.5 mg/dL was the approximate threshold for both increased morbidity and mortality.

CONCLUSIONS

Modest preoperative serum creatinine elevation (>1.5 mg/dL) is a significant predictor of risk-adjusted morbidity and mortality after general surgery. A preoperative serum creatinine of 1.5 mg/dL or higher is a readily available marker for potential adverse outcomes after general surgery.

Cardiac surgery in moderate to end-stage renal failure: analysis of risk factors

BACKGROUND

The incremental surgical risk caused by different categories of renal failure is not well defined.

METHODS

Data from 159 patients with moderate to end-stage renal dysfunction, who had consecutive operations using cardiopulmonary bypass, were included in a multivariate analysis of morbidity and survival. Ninety-nine patients had preoperative serum creatinine levels (PSCL) of 1.9 to 2.5 mg/dL (moderate), 36 had PSCL higher than 2.5 mg/dL and were not dialysis dependent (severe), and 24 required chronic dialysis (end-stage dysfunction).

RESULTS

Operative mortality was 4% with moderate dysfunction and compared favorably with 16.7% in severe and 8% in end-stage dysfunction (p < 0.05). Independent predictors of death were severe non-dialysis-dependent renal dysfunction (p < 0.05), diabetes (p < 0.05), and cardiopulmonary bypass time (p < 0.01). Severe renal dysfunction (p < 0.01) and diabetes (p < 0.01) also predicted pulmonary and neurologic morbidity. Freedom from late death at 4 years was 82% +/- 5% with moderate, 49% +/- 10% with severe, and 60% +/- 10% with end-stage dysfunction (p < 0.01). Time to late death was adversely affected by severe (p < 0.05) and end-stage dysfunction (p < 0.01). Persistent improvement of symptoms was observed in all subgroups.

CONCLUSIONS

Satisfactory early and late surgical outcomes may be expected in patients with moderate renal failure, but outcomes are often poor with severe non-dialysis-dependent and end-stage renal dysfunction.

Causes of prolonged mechanical ventilation after coronary artery bypass surgery

STUDY OBJECTIVE

To evaluate causes of failure to be extubated (FTE) after coronary artery bypass graft (CABG) surgery.

DESIGN

Prospective observational study.

SETTING

Cardiovascular surgical ICU.

PATIENTS

Four hundred patients undergoing CABG surgery. Following surgery, patients were extubated by a standardized respiratory protocol and were assessed at 8, 24, and 48 h. Patients who could not be extubated at 8 h were designated as FTE, and at 24 and 48 h they were labeled as requiring prolonged mechanical ventilation (PMV) > 24 h and PMV > 48 h, respectively.

MEASUREMENTS AND RESULTS

One hundred sixty-seven patients (41.75%), 27 patients (6.75%), and 21 (5.25%) patients, respectively, could not be extubated at 8, 24, and 48 h. Depressed level of consciousness was the most common reason for FTE in 58 of 167 patients (34.7%). The main cause of depressed level of consciousness was prolonged sedation due to anesthetic agents (51 patients; 30.5%). Hypoxemia was the most common cause for PMV for > 24 h (15 patients) and PMV > 48 h (13 patients). The causes of hypoxemia were cardiogenic and noncardiogenic pulmonary edema, pneumonia, and "hypoxemia of unknown etiology." Tachypnea due to acid-base disturbances was a reason for FTE and PMV for > 24 h in 27 and 3 patients, respectively. Cardiovascular instability was a rare reason for FTE. Postoperative bleeding was a cause for PMV in 18 patients. Four patients had more than a single reason for FTE at each assessment. Different causes have a variable effect on the duration of mechanical ventilation.

CONCLUSION

The causes of PMV are heterogeneous, vary with time, and have a variable impact on the duration of mechanical ventilation required after the patient undergoes CABG surgery.

Outcomes of patients with chronic renal insufficiency in the bypass angioplasty revascularization investigation

BACKGROUND

Although severe chronic kidney disease (CKD) is an independent predictor of mortality among patients with coronary artery disease, the impact of mild CKD on morbidity and mortality has not been fully defined.

METHODS AND RESULTS

Morbidity and mortality for the 3608 patients with multivessel coronary artery disease enrolled in the Bypass Angioplasty Revascularization Investigation randomized trial and registry were compared on the basis of the presence and absence of CKD, defined as a preprocedure serum creatinine level of >1.5 mg/dL. Seventy-six patients had CKD. Patients with renal insufficiency were older and more likely to have a history of diabetes, hypertension, and other comorbidities. Among patients undergoing PTCA, patients with CKD had a greater frequency of in-hospital death and cardiogenic shock (P<0.05 and 0.01, respectively). There was a trend toward a larger proportion of patients with CKD experiencing angina at 5 years (P=0.079). Patients with CKD had more cardiac admissions (P=0.003 and <0.0001 for patients undergoing PTCA and CABG, respectively) and a shorter time to subsequent CABG after initial revascularization than patients without CKD (P=0.01). CKD was associated with a higher risk of death at 7 years, both of all causes (relative risk 2.2, P<0.001) and of cardiac causes (relative risk 2.8, P<0.001).

CONCLUSIONS

CKD is associated with an increased risk of recurrent hospitalization, subsequent CABG, and mortality. This increased risk of death is independent of and additive to the risk associated with diabetes.

The impact of renal insufficiency on clinical outcomes in patients undergoing percutaneous coronary interventions

OBJECTIVES

We sought to determine the effect of varying degrees of renal insufficiency on death and cardiac events during and after a percutaneous coronary intervention (PCI).

BACKGROUND

Patients with end-stage renal disease have a high mortality from coronary artery disease. Little is known about the impact of mild and moderate renal insufficiency on clinical outcomes after PCI.

METHODS

Cardiac mortality and all-cause mortality were determined for 5,327 patients undergoing PCI from January 1, 1994, to August 31, 1999, at the Mayo Clinic, based on the estimated creatinine clearance or whether the patient was on dialysis.

RESULTS

In-hospital mortality was significantly associated with renal insufficiency (p = 0.001). Even after successful PCI, one-year mortality was 1.5% when the creatinine clearance was > or =70 ml/min (n = 2,558), 3.6% when it was 50 to 69 ml/min (n = 1,458), 7.8% when it was 30 to 49 ml/min (n = 828) and 18.3% when it was < 30 ml/min (n = 141). The 18.3% mortality rate for the group with < 30 ml/min creatinine clearance was similar to the 19.9% mortality rate in patients on dialysis (n = 46). The mortality risk was largely independent of all other factors.

CONCLUSIONS

Renal insufficiency is a strong predictor of death and subsequent cardiac events in a dose-dependent fashion during and after PCI. Patients with renal insufficiency have more baseline cardiovascular risk factors, but renal insufficiency is associated with an increased risk of death and other adverse cardiovascular events, independent of all other measured variables.

Preventive stent placement for renal artery stenosis prior to emergent coronary artery bypass grafting

PURPOSE

To illustrate the benefits of treating severe renal artery stenosis in renally compromised patients prior to surgery for coronary artery disease.

CASE REPORT

A 63-year-old woman with unstable angina, severe coronary artery disease, and long-term severe renal impairment with a single functioning kidney underwent renal stent placement for high-grade renal artery stenosis prior to coronary artery surgery. The procedure improved her serum creatinine from 528 micromol/L at baseline to 385 micromol/L, and she subsequently underwent coronary artery bypass grafting without deterioration in her renal function. At 1 year, the patient has a serum creatinine of 400 micromol/L, and there is no evidence of in-stent stenosis.

CONCLUSIONS

Percutaneous renal angioplasty or stenting prior to coronary surgery in patients with concomitant renal and coronary artery disease may reduce perioperative renal deterioration in this specific group of patients.

Reduced kidney function and anemia as risk factors for mortality in patients with left ventricular dysfunction

OBJECTIVES

We sought to evaluate the relationship between the level of kidney function, level of hematocrit and their interaction on all-cause mortality in patients with left ventricular (LV) dysfunction.

BACKGROUND

Anemia and reduced kidney function occur frequently in patients with heart failure. The level of hematocrit and its relationship with renal function have not been evaluated as risk factors for mortality in patients with LV dysfunction.

METHODS

We retrospectively examined the Studies Of LV Dysfunction (SOLVD) database. Glomerular filtration rate (GFR) was predicted using a recently validated formula. Kaplan-Meier survival analyses were used to compare survival times between groups stratified by level of kidney function (predicted GFR) and hematocrit. Cox proportional-hazards regression was used to explore the relationship of survival time to level of kidney function, hematocrit and their interaction.

RESULTS

Lower GFR and hematocrit were associated with a higher prevalence of traditional cardiovascular risk factors. In univariate analysis, reduced kidney function and lower hematocrit, in men and in women, were risk factors for all-cause mortality (p < 0.001 for both). After adjustment for other factors significant in univariate analysis, a 10 ml/min/1.73 m(2) lower GFR and a 1% lower hematocrit were associated with a 1.064 (95% CI: 1.033, 1.096) and 1.027 (95% CI: 1.015, 1.038) higher risk for mortality, respectively. At lower GFR and lower hematocrit, the risk was higher (p = 0.022 for the interaction) than that predicted by both factors independently.

CONCLUSIONS

Decreased kidney function and anemia are risk factors for all-cause mortality in patients with LV dysfunction, especially when both are present. These relationships need to be confirmed in additional studies.

Coronary artery bypass grafting for patients with non-dialysis-dependent renal dysfunction (serum creatinine > or =2.0 mg/dl)

INTRODUCTION

Patients with renal dysfunction carry a risk of coronary atherosclerosis. The purpose of this study was to evaluate the outcome after coronary artery bypass grafting (CABG) in patients with decreased renal function (serum creatinine > or =2.0 mg/dl).

METHODS

We retrospectively analyzed consecutive patients who had undergone isolated CABG at Shin-Tokyo Hospital between May 1, 1991 and April 31, 2000. Preoperative, perioperative, and follow-up data of the non-dialysis-dependent patients with preoperative serum creatinine equal to or more than 2.0mg/dl (group R, n=59) were collected, and compared with those of the control patients (serum creatinine < 2.0, group C, n=1666). Group R was further divided into the off-pump and on-pump CABG group and their perioperative results were compared.

RESULTS

Group R included 51 males and eight females with a mean age of 66.4. The mean number of anastomoses was not significantly different between groups; however, clump time and pump time were longer in group R. Postoperative recovery was longer in group R than in group C, which is associated with a more frequent occurrence of major complications (28.8% in group R and 10.7% in group C, P<0.0001) and mortalities (6.8% in group R and 0.5% in group C, P<0.0005). The patients who underwent off-pump CABG experienced relatively faster recovery than those who underwent on-pump CABG, despite decreased renal function. At the mean follow-up of 2.4 years, the actuarial 3-year survival rate of groups R and C were 75.3 and 96.9%, respectively (P<0.0001), excluding hospital mortality. The actuarial 3-year cardiac event-free rate was 76.7% in group R and 87.3% in group C (P<0.05).

CONCLUSIONS

Patients with decreased renal function carry significant operative risks and require prolonged hospital care. Even after adequate surgical revascularization was completed, the long-term cardiac event-free and survival rates in the patients with renal dysfunction were inferior to the patients with normal renal function.

Postoperative renal insufficiency

The poor clinical outcomes associated with postoperative HARI necessitate increased vigilance for HARI detection and intervention to minimize the progression to dialysis dependency. Patient survival significantly worsens if HARI requires the initiation of dialysis. Postoperative changes, including intravascular volume expansion, SIRS, and reduced lean body mass, frequently confound the detection of HARI. Serum creatinine levels frequently do not reflect the decreased renal function because creatinine production rate is decreased with reduced lean body mass, and the serum creatinine concentration is reduced by increased intravascular volume expansion and increased volume of distribution associated with anasarca. Additional indices of renal function must be used postoperatively, including urine output, net volume status, urinalysis with microscopic examination of the spun pellet, and corrected estimations of creatinine clearance. Few therapeutic interventions currently exist to reverse HARI other than optimization of renal perfusion and limitation of nephrotoxin exposure. Dialysis remains a cornerstone of maintenance therapy for refractory and severe HARI. Selection of dialysis modality continues to be based on modality availability and patient stability.

Stroke after coronary artery bypass: incidence, predictors, and clinical outcome

BACKGROUND AND PURPOSE

Early postoperative stroke is a serious adverse event after coronary artery bypass grafting (CABG). This study sought to investigate risk factors, prevalence, and prognostic implications of postoperative stroke in patients undergoing CABG.

METHODS

We investigated the predictors of postoperative stroke (n=333, 2%) in 16 528 consecutive patients who underwent CABG between September 1989 and June 1999 in our institution. Predictors of postoperative stroke were identified by logistic regression analysis.

RESULTS

Among the preoperative and postoperative factors, significant correlates of stroke included (1) chronic renal insufficiency (P<0.001), (2) recent myocardial infarction (P=0.01), (3) previous cerebrovascular accident (P<0.001), (4) carotid artery disease (P<0.001), (5) hypertension (P<0.001), (6) diabetes (P=0.001), (7) age >75 years (P=0.008), (8) moderate/severe left ventricular dysfunction (P=0.01), (9) low cardiac output syndrome (P<0.001), and (10) atrial fibrillation (P<0.001). Postoperative stroke was associated with longer postoperative stay (11+/-4 versus 7+/-3 days for patients without stroke, P<0.001) and with higher in-hospital mortality (14% versus 2.7% for patients without stroke; P<0.001).

CONCLUSIONS

Stroke after CABG is associated with high short-term morbidity and mortality. Increased stroke risk can be predicted by preoperative and postoperative clinical factors.

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.

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.

Risks of morbidity and mortality in dialysis patients undergoing coronary artery bypass surgery. Northern New England Cardiovascular Disease Study Group

BACKGROUND

Although dialysis patients are undergoing CABG with increasing frequency, large studies specifically comparing patient characteristics and procedure-related risks in this population have not been performed.

METHODS AND RESULTS

We conducted a regional prospective cohort study of 15,500 consecutive patients undergoing CABG in northern New England from 1992 to 1997. We used multiple logistic regression analysis to examine associations between preoperative dialysis-dependent renal failure and postoperative events and to adjust for potentially confounding variables. The 279 dialysis-dependent renal failure patients (1.8%) were 4.4 times more likely to experience in-hospital mortality than were other CABG patients (12.2% versus 3.0%, respectively; P:<0.001). Dialysis-dependent renal failure patients were older and had more comorbidities and more severe cardiac disease than did other CABG patients. After adjusting for these factors in multivariate analysis, however, dialysis-dependent renal failure patients remained 3.1 times more likely to die after CABG (adjusted odds ratio [OR] 3.1, 95% CI 2.1 to 4.7; P:<0.001). Dialysis-dependent renal failure patients compared with other CABG patients also had a substantially increased risk of postoperative mediastinitis (3.6% versus 1.2%, respectively; adjusted OR 2.4, 95% CI 1.2 to 4.7; P:=0.011) and postoperative stroke (4.3% versus 1.7%, respectively; adjusted OR 2. 1, 95% CI 1.1 to 3.9; P:=0.016), even after controlling for potentially confounding variables. Risks of reexploration for bleeding were similar for patients with and without dialysis-dependent renal failure.

CONCLUSIONS

Preoperative dialysis-dependent renal failure is a strong independent risk factor for in-hospital mortality and mediastinitis after CABG.