Subclinical changes in serum creatinine and mortality after coronary artery bypass grafting

Early Creatinine Changes After Aortic Valve Replacement and Late Survival, Heart Failure, and Chronic Kidney Disease in a National Registry

BACKGROUND

The impact of small increases in serum creatinine after surgical aortic valve replacement (SAVR) that fail to meet the acute kidney injury stage 1 criteria is unknown. The aim of this study was to investigate prognosis after primary SAVR in patients with small increases in postoperative serum creatinine.

METHODS

This observational cohort study included all adult patients who underwent primary SAVR in Sweden from 2009 to 2022. The primary outcome was all-cause mortality. Secondary outcomes were chronic kidney disease and heart failure. Regression standardization addressed confounding.

RESULTS

In 16,766 patients, 4074 (24.2%) had no change in postoperative serum creatinine, 5764 (34.3%) had a small increase in postoperative serum creatinine (0.06 mg/dL ≤ Δserum creatinine <0.3 mg/dL), and 2753 (16.4%) fulfilled the Kidney Disease Improving Global Outcomes acute kidney injury stage 1 criteria. The mean age was 67 years, and 31% of patients were female. No significant difference in long-term all-cause mortality was observed in the no change group at 13 years compared with the small increase group (absolute survival difference, 2.3% [95% CI, 0%-4.6%]). A stepwise increase in the risk of 30-day mortality was observed with increasing changes in serum creatinine. At 13 years of follow-up, there was a significant difference in the risk of chronic kidney disease (absolute difference, 2.8% [95% CI, 1.0%-4.5%]) and heart failure (absolute difference, 3.5% [95% CI, 1.3%-5.7%]) between the no change and small increase groups.

CONCLUSIONS

A small increase in postoperative serum creatinine after SAVR was associated with an increased risk of adverse outcomes. The acute kidney injury definition may benefit from including more reliable and specific biomarkers together with small creatinine increases to detect kidney injury.

Isolated coronary artery bypass grafting in septuagenarians

As life expectancy increases, the number of elderly patients with coronary artery disease requiring coronary artery bypass grafting (CABG) also increases. This study aims to analyse the outcomes of isolated CABG in septuagenarians. Isolated CABG patients between 70 and 79 years from January 1, 2017, to December 31, 2022, were included. Clinical data were obtained from medical records and through a phone call. Out of 618 isolated CABG patients, 132 (21.35%) were septuagenerians. Off-pump and on-pump beating heart CABG was performed in 123 (93.18%) and 9 (6.81%), respectively. Emergency CABG was performed in two patients (1.51%). The mean expected EuroSCORE II (European System for Cardiac Operative Risk evaluation) operative mortality was 2.51%. The incidence of in-hospital mortality, stroke and atrial fibrillation was 1.5%, 0.85% and 6.06%, respectively. An intra-aortic balloon pump was used in six patients (4.5%). The actuarial survival at 1 year, 5 years and 6 years were 98.1 ± 1.4%, 85.5 ± 4.7% and 85.5 ± 4.7%, respectively. The average duration of ventilation, intensive care unit (ICU) and hospital stay were 14.18 ± 10.37 h, 2.48 ± 0.89 days and 6.07 ± 1.8 days, respectively. EuroSCORE-II grading was associated with major adverse cardiovascular events. We conclude that performing CABG on septuagenarians in Indian population is safe.

Two novel nomograms predict 30-day mortality after off-pump coronary artery bypass grafting

Background

With the development of surgical techniques and medical equipment, the mortality rate of off-pump coronary artery bypass grafting (CABG) has been declining year by year, but there is a lack of convenient and accurate predictive models. This study aims to use two nomograms to predict 30-day mortality after off-pump CABG.

Methods

Patients with isolated off-pump CABG from January 2016 to January 2021 were consecutively enrolled. Potential predictive factors were first screened by lasso regression, and then predictive models were constructed by multivariate logistic regression. To earlier identify high-risk patients, two nomograms were constructed for predicting mortality risk before and after surgery.

Results

A total of 1840 patients met the inclusion and exclusion criteria. The 30-day mortality was 3.97 % (73/1840) in this cohort. Multivariate logistic analysis showed that age, BMI<18.5 kg/m2, surgical time, creatinine, LVEF, history of previous stroke, and major adverse intraoperative events (including conversion to cardiopulmonary bypass or implantation of intra-aortic balloon pump) were independently associated with 30-day mortality. Model 1 contained preoperative and intraoperative variables, and the AUC was 0.836 (p < 0.001). The AUC of the K-fold validation was 0.819. Model 2 was only constructed by preoperative information. The AUC was 0.745 (p < 0.001). The AUC of the K-fold validation was 0.729. The predictive power of Model 1 was significantly higher than the SinoScore (DeLong's test p < 0.001).

Conclusions

The two novel nomograms could be conveniently and accurately used to predict the risk of 30-day mortality after isolated off-pump CABG.

Predictors of outcome after CABG in the South-Asian community: a propensity matched analysis

BACKGROUND

Ethnicity is not incorporated into standardized pre-operative risk-stratification tools for cardiac surgery. This study compared short-term outcomes following coronary artery bypass graft (CABG) surgery in South Asian and non-Asian patients.

METHODS

Consecutive patients undergoing isolated CABG surgery via sternotomy between the years 2011 and 2019 were retrospectively analyzed. Initially, 1957 patients were identified (799 South-Asian, 40.8%). The patient groups were then propensity matched according to 10 relevant pre-operative covariates (age, body mass index, pulmonary disease, renal failure, smoking, diabetes, ventricular function, renal failure): 675 non-Asian patients were matched against 675 Asian patients.

RESULTS

Operative mortality was 1.77% and similar between the two groups (p = 0.447). Multivariate regression analysis found predictors of operative mortality to be pre-operative serum creatinine, age, left ventricular (LV) impairment, and extent of coronary disease. The effect of creatinine on mortality was selective for South-Asian patients (p = 0.015). LV impairment was a predictor of mortality in non-Asian patients, however this effect did not exist in South-Asian patients. Predictors of short-term complications (composite of death, stroke, reoperation, hemofiltration, and pneumonia) were age and creatinine (coefficient 0.002, 95% CI 0.0004-0.004, p = 0.019) in the overall cohort. Subgroup analysis found age to remain a selective negative predictor of complications in South-Asian patients. Cox regression analysis found creatinine, age, and LVEF to influence 10-year survival, whilst ethnicity was not a predictor.

CONCLUSION

This study highlights the cumulative risk associated with ethnicity and renal disease in predicting short-term outcomes following CABG. This warrants further investigations in larger populations, thus guiding pre-operative risk-stratification.

Risk factors for development of acute renal failure in 5077 coronary artery bypass grafting patients in the current era

BACKGROUND

Acute renal failure (ARF) is one of the major complications after coronary artery bypass grafting (CABG) surgery. The risk factors are changing along with the technical evolution. The aim of this study was to identify the risk factors for ARF requiring dialysis after CABG surgery in the current era.

METHODS

Between April 2012 and November 2019, 5077 consecutive patients who underwent CABG were analyzed retrospectively. The patients were divided into ARF group and non-ARF group according to whether ARF occurred and dialysis was required after operation. Univariate analysis was performed to find possible factors associated with ARF. Any variables that had trends to be associated with ARF were included in stepwise multiple logistic regression analysis.

RESULTS

Of the 5077 patients who underwent CABG, 53 (1.04%) developed ARF requiring dialysis whereas 5024 (98.96%) were in non-ARF group. Cardiopulmonary bypass (CPB) time (odds ratio [OR], 1.009; 95% confidence interval [CI], 1.003-1.016; p = .006), insertion of intra-aortic balloon pump (IABP; OR, 19.294; 95% CI, 5.49-67.808; p = .000), and low ejection fraction (EF; OR, 0.943; 95% CI, 0.894-0.994; p = .030) were independent risk factors for development of ARF requiring dialysis in patients undergoing CABG surgery.

CONCLUSION

Our study identified prolonged CPB time, insertion of IABP, and low EF as independent risk factors for developing ARF requiring dialysis after CABG. The results suggest that shortening of CPB time and protection of cardiac function are important factors to prevent ARF and that special care should be taken to protect the renal function when the patient need insertion of IABP.

Biochemical interaction of pyrvinium in gentamicin-induced acute kidney injury by modulating calcium dyshomeostasis and mitochondrial dysfunction

Acute kidney injury (AKI) has a poor clinical prognosis and increases the risk of chronic kidney failure (CKD). It is a common complication of organ failure in hospitalised patients (10-15% of all hospitalizations) and in intensive care unit (ICU) patients, with an incidence of up to 50%. Concerning ICU, AKI has a mortality rate ranging from 27% to 35%, rising to 60%-65% when dialysis is needed, with roughly 5%-20% of survivors requiring dialysis on discharge. AKI is believed to cause over 7 million deaths per year worldwide. Currently, there is no treatment for AKI or its progression to CKD. When activated by AKI, numerous pathways have been suggested as possible contributors to CKD progression. Wnt/β-catenin is a crucial regulator of kidney development that increases following the injury. Despite the overwhelming evidence that Wnt/β-catenin promotes AKI, tubulointerstitial fibrosis, a hallmark of CKD progression, is also promoted by this pathway. The therapeutic potential of Wnt/β-catenin in the treatment of AKI and the progression from AKI to CKD is being studied. This hypothesis aims to determine whether the Wnt/β-catenin inhibitor pyrvinium has a beneficial effect on the renal dysfunction and damage caused by Gentamicin.

Urinary TIMP-2 and IGFBP-7 protein levels as early predictors of acute kidney injury after cardiac surgery

BACKGROUND

Acute kidney injury (AKI) is a frequent complication associated with on-pump cardiac surgery. Early recognition may alter their prognosis. Therefore, the urinary concentrations of TIMP-2 (tissue inhibitor of metalloproteinases-2) and IGFBP7 (insulin-like growth factor-binding protein) as predictors for AKI were studied.

METHODS

Repetitive blood and urine samples were collected consecutively from 50 patients. Demographic, intra-, and postoperative data were recorded prospectively. To calculate the production of the TIMP-2 and IGFBP-7 protein concentrations, urinary samples were taken preoperatively, intraoperatively at 30 and 60 min after aortic clamping and at 0, 6, 12, and 24 h after admission to the intensive care unit (ICU).

RESULTS

AKI occurred in 14 patients (28%), all of them at Kidney Disease: Improving Global Outcomes stage 1. Predictive value for [TIMP-2] × [IGFBP7] was shown at 0 and 24 h after admission to ICU. At 0 h, the sensitivity was 84.6% and the specificity 55.6% for an ideal calculated cutoff at 0.07. After 24 h, the ideal cutoff amounted to 0.35 with a sensitivity of 53.8% and a specificity of 88.2%. The receiver operating characteristic curves demonstrated areas under the curve of 0.725 and 0.718. The suggested cutoffs of 0.3 and 2.0 could not be confirmed. The serum creatinine was reached to the peak median within 48 h after admission to ICU.

CONCLUSION

Postoperative risk assessment for the development of AKI can be established by [ TIMP - 2 ] × [ IGFBP 7 ] . Previously suggested cutoff values could not be confirmed. A correlation with urinary dilution parameters may enable the identification of more universal cutoffs.

Early recognition of cardiac surgery-associated acute kidney injury: lack of added value of TIMP2 IGFBP7 over short-term changes in creatinine (an observational pilot study)

Background

For the detection of cardiac surgery-associated acute kidney injury (CS-AKI), the performance of urine tissue inhibitor of metalloproteinase 2 insulin-like growth factor-binding protein 7 (TIMP2 IGFBP7) has never been compared with that of very early changes in plasma creatinine (∆pCr). We hypothesized that, in the context of perioperative haemodilution, lack of postoperative decrease in pCr would be of honourable performance for the detection of CS-AKI. We therefore aimed at comparing these biomarkers and their kinetics (primary objective). As secondary objectives, we assessed plasma neutrophil gelatinase-associated lipocalin (pNGAL), cystatin C (pCysC) and urea (pUrea). We also determined the ability of these biomarkers to early discriminate persistent from transient CS-AKI.

Methods

Patients over 75 years-old undergoing aortic valve replacement with cardiopulmonary bypass (CPB) were included in this prospective observational study. Biomarkers were measured before/after CPB and at the sixth postoperative hour (H6).

Results

In 65 patients, CS-AKI occurred in 27 (42%). ∆pCr from post-CPB to H6 (∆pCr_postCPB-H6): outperformed TIMP2 IGFBP7 at H6 and its intra- or postoperative changes: area under the receiver operating characteristic curve (AUC_ROC) of 0.84 [95%CI:0.73–0.92] vs. ≤0.67 [95%CI:0.54–0.78], p ≤ 0.03. The AUC_ROC of pNGAL, pCysC and pUrea did not exceed 0.72 [95%CI:0.59–0.83]. Indexing biomarkers levels for blood or urine dilution did not improve their performance. Combining TIMP2 IGFBP7 and ∆pCr_postCPB-H6 was of no evident added value over considering ∆pCr_postCPB-H6 alone. For the early recognition of persistent CS-AKI, no biomarker outperformed ∆pCr_postCPB-H6 (AUC_ROC = 0.69 [95%CI:0.48–0.85]).

Conclusions

In this hypothesis-generating study mostly testing early detection of mild CS-AKI, there was no evident added value of the tested modern biomarkers over early minimal postoperative changes in pCr: despite the common perioperative hemodilution in the setting of cardiac surgery, if pCr failed to decline within the 6 h after CPB, the development of CS-AKI was likely. Confirmatory studies with more severe forms of CS-AKI are required.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12871-021-01387-6.

A randomised controlled trial of succinylated gelatin (4%) fluid on urinary acute kidney injury biomarkers in cardiac surgical patients

Background

Fluid resuscitation is frequently required for cardiac surgical patients admitted to the intensive care unit. The ideal fluid of choice in regard to efficacy and safety remains uncertain. Compared with crystalloid fluid, colloid fluid may result in less positive fluid balance. However, some synthetic colloids are associated with increased risk of acute kidney injury (AKI). This study compared the effects of succinylated gelatin (4%) (GEL) with compound sodium lactate (CSL) on urinary AKI biomarkers in patients after cardiac surgery.

Methods

Cardiac surgical patients who required an intravenous fluid bolus of at least 500 mL postoperatively were randomly allocated to receive GEL or CSL as the resuscitation fluid of choice for the subsequent 24 h. Primary outcomes were serial urinary neutrophil gelatinase-associated lipocalin (NGAL) and cystatin C concentrations measured at baseline, 1 h, 5 h and 24 h after enrolment, with higher concentrations indicating greater kidney injury. Secondary biomarker outcomes included urinary clusterin, α1-microglobulin and F₂-isoprostanes concentrations. Differences in change of biomarker concentration between the two groups over time were compared with mixed-effects regression models. Statistical significance was set at P < 0.05.

Results

Forty cardiac surgical patients (n = 20 per group) with similar baseline characteristics were included. There was no significant difference in the median volume of fluid boluses administered over 24 h between the GEL (1250 mL, Q1–Q3 500–1750) and CSL group (1000 mL, Q1–Q3 500–1375) (P = 0.42). There was a significantly greater increase in urinary cystatin C (P < 0.001), clusterin (P < 0.001), α1-microglobulin (P < 0.001) and F₂-isoprostanes (P = 0.020) concentrations over time in the GEL group, compared to the CSL group. Change in urinary NGAL concentration (P = 0.68) over time was not significantly different between the groups. The results were not modified by adjustment for either urinary osmolality or EuroSCORE II predicted risk of mortality.

Conclusions

This preliminary randomised controlled trial showed that use of succinylated gelatin (4%) for fluid resuscitation after cardiac surgery was associated with increased biomarker concentrations of renal tubular injury and dysfunction, compared to crystalloid fluid. These results generate concern that use of intravenous gelatin fluid may contribute to clinically relevant postoperative AKI.

Trial registration ANZCTR.org.au, ACTRN12617001461381. Registered on 16th October, 2017, http://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=373619&isReview=true.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40635-021-00412-9.

Defining Acute Kidney Injury

Acute kidney injury (AKI) is a syndrome of impaired kidney function associated with reduced survival and increased morbidity. International consensus criteria were developed based on changes in serum creatinine and urine output. Based on these definitions, epidemiologic studies have shown strong associations with clinical outcomes including death and dialysis. However, numerous limitations exist for creatinine and urine volume as markers of AKI and novel biomarkers have been developed to detect cellular stress or damage. Persistent AKI and acute kidney disease are relatively new concepts that explore the idea of AKI as a continuum with chronic kidney disease.

Perfusion parameters during cardiopulmonary bypass as a predictor of acute kidney injury after aortic valve replacement

Background

Acute kidney injury (AKI) is a major complication after cardiac surgery and significantly affects postoperative mortality and morbidity. This study was conducted to evaluate the association between target pump flow to achieve adequate oxygen delivery (DO₂) and postoperative renal function after aortic valve replacement.

Methods

From January 2017 to May 2020, 281 patients (male:female, 160:121; mean age, 68±11 years) who underwent aortic valve replacement were retrospectively reviewed. Target pump flow was calculated based on DO₂ level of 280 mL/min/m². The primary endpoint was postoperative renal dysfunction, defined as the ratio of postoperative peak creatinine level to preoperative value. The ratio of the lowest actual pump flow to the ideal target pump flow, other hemodynamic variables related with cardiopulmonary bypass, intraoperative transfusion, and preoperative characteristics were analyzed to identify factors associated with the primary endpoint using a multivariable linear regression model.

Results

Preoperative and peak postoperative creatinine levels were 0.94±0.33 mg/dl and 1.15±0.56 mg/dl, respectively (ratio, 1.22±0.33). The ideal target pump flow was 4.70±0.59 L/min, whereas the lowest actual pump flow was 3.77±0.47 L/min (ratio, 0.81±0.13). The multivariable model showed that the ratio of the lowest pump flow to target pump flow (β±standard error, –0.405±0.162, P=0.013), as well as sex, stroke history, emergency operation, and transfusion of red blood cells were associated with the primary endpoint.

Conclusions

Low actual nadir pump flow compared to the ideal target pump flow based on DO₂ is associated with the risk of AKI after aortic valve replacement.

The impact of diabetes mellitus on acute kidney injury after coronary artery bypass grafting

Background

Diabetes mellitus(DM) is an indicator affects postoperative mortality and morbidity after coronary artery bypass grafting (CABG). Acute kidney injury (AKI) is one of the frequent postoperative complications after CABG. This multi-centre register study designed to investigate the impact of DM on postoperative AKI in primary isolated CABG patients.

Methods

We included all patients (n = 4325) from Jiangsu Province CABG register who underwent primary isolated CABG from September 2017 to August 2019. The patients were divided into 3 groups: No-DM group(n = 3067), DM-oral group (DM with oral hypoglycemic agents, n = 706) and DM-insulin group (DM with insulin treatment, n = 552). The development and severity of AKI were based on Acute Kidney Injury Network (AKIN) criteria.

Results

There were totally 338, 108 and 145 patients developed AKI in No-DM, DM-oral and DM-insulin group respectively. Comparing with No-DM group, DM-oral group had a higher rate of AKI(χ² = 10.071, p = 0.002), DM-insulin group had a higher rate(χ² = 94.042, p<0.001) and severity of AKI(χ² = 10.649, p = 0.005). The adjusted odds ratio for AKI was 1.26 (95% CI 1.03–1.57) in DM-oral group and 3.92 (95% CI 3.27–5.16) in DM-insulin group, in comparison with No-DM group.

Conclusions

Independent of baseline renal function or cardiac function, DM was associated with an increased risk of AKI after CABG, especially in patients with insulin treatment, who also had a higher severity of AKI.

A Better Predictor of Acute Kidney Injury After Cardiac Surgery: The Largest Area Under the Curve Below the Oxygen Delivery Threshold During Cardiopulmonary Bypass

Background

The aim of this study was to compare the predictive accuracy of acute kidney injury (AKI) after cardiac surgery using cardiopulmonary bypass for the largest area under the curve (AUC) below the oxygen delivery (DO₂) threshold and the cumulative AUC below the DO₂ threshold.

Methods and Results

From March 2017 to October 2019, 202 patients who had undergone cardiac surgery with cardiopulmonary bypass were enrolled. The perfusion parameters were recorded every 20 seconds, and the DO₂ (10×pump flow index [L/min per m²]×[hemoglobin (g/dL)×1.36×arterial oxygen saturation (%)+partial pressure of arterial oxygen (mm Hg)×0.003]) threshold of 300 mL/min per m² was considered to define sufficient DO₂. The nadir DO₂, the cumulative AUC below the DO2300, and the largest AUC below the DO2300 were used to predict the incidence of AKI. Postoperative AKI was observed in 12.4% of patients (25/202). By multivariable analysis, the largest AUC below the DO2300 ≥880 (odds ratio [OR], 4.9; 95% CI, 1.2–21.5 [P=0.022]), preoperative hemoglobin concentration ≤11.6 g/dL (OR, 7.6; 95% CI, 2.0–32.3 [P=0.004]), and red blood cell transfusions during cardiopulmonary bypass ≥2 U (OR, 3.3; 95% CI, 1.0–11.1 [P=0.041]) were detected as independent risk factors for AKI. Receiver operating curve analysis revealed that the largest AUC below the DO2300 was more accurate to predict postoperative AKI compared with the nadir DO₂ and the cumulative AUC below the DO2300 (differences between areas, 0.0691 [P=0.006] and 0.0395 [P=0.001]).

Conclusions

These data suggest that a high AUC below the DO2300 is an important independent risk factor for AKI after cardiopulmonary bypass, which could be considered for risk prediction models of AKI.

The Impact of Acute Kidney Injury in the Perioperative Period on the Incidence of Postoperative Delirium in Patients Undergoing Coronary Artery Bypass Grafting-Observational Cohort Study

Recent data indicate that acute kidney damage leads to inflammation in the brain and other distant organs. The purpose of this study was to investigate the effect of acute kidney injury (AKI) according to the Kidney Disease Improving Global Outcome (KDIGO) criteria on the occurrence of postoperative delirium in patients undergoing coronary artery bypass grafting (CABG). We performed a retrospective cohort analysis that included all consecutive patients undergoing elective CABG. The CAM-ICU (Confusion Assessment Method for Intensive Care Unit) was used for delirium assessment. Patients were divided into four groups, depending on the occurrence of AKI in the perioperative period according to KDIGO criteria. Overall, 902 patients were included in the final analysis, the mean age was 65.95 ± 8.01 years, and 76.83% were males (693/957). The majority of patients presented with normal kidney function-baseline creatinine level of 0.91 ± 0.21 (mg/dL). The incidence of AKI in the perioperative setting was 22.17% (200/902). Postoperative delirium was diagnosed in 115/902 patients (12.75%). Compared with no AKI, the odds of developing POD were increased for KDIGO stage 1 (OR 2.401 (95% confidence interval 1.484–3.884), p < 0.001); KDIGO stage 2 (OR 3.387 (95% confidence interval 1.459–7.866), p = 0.005); and highest for KDIGO stage 3 (OR equal to 9.729 (95% confidence interval 2.675–35.382), p = 0.001). Acute kidney injury, based on AKI staging, should be regarded as an independent risk factor for postoperative delirium after cardiac surgery.

The effect of time between angiography and coronary artery bypass grafting on postoperative acute kidney injury in patients with diabetes mellitus

Background

This study aims to investigate the effect of time interval between coronary angiography and coronary artery bypass grafting surgery on postoperative acute kidney injury in patients with diabetes mellitus.

Methods

Between December 2013 and November 2016, a total of 421 diabetic patients (274 males, 147 females; mean age 60±9.2 years; range, 31 to 84 years) who underwent coronary artery bypass grafting were included in the study. Data including demographic characteristics of the patients, comorbidities, medical, and surgical histories, previous coronary angiographies, and operative and laboratory results were retrospectively analyzed. The patients were divided into two groups as those with acute kidney injury (n=108) and those without acute kidney injury (n=313). The Risk, Injury, Failure, Loss, End-Stage Kidney Disease (RIFLE) criteria were used to define acute kidney injury. The patients were further classified into three subgroups according to the time interval: 0-3 days, 4-7 days, and >7 days.

Results

There was no statistically significant difference in the median time between coronary angiography and coronary artery bypass grafting between the patients with and without acute kidney injury (11.5 and 12.0 days; respectively p=0.871). There was no significant difference in the risk factors for acute kidney injury among the subgroups. Multivariate analysis revealed that previous myocardial infarction (odds ratio [OR]: 5.192, 95% confidence interval [CI]: 2.176-12.38; p<0.001) and the increase in the creatinine levels in the first postoperative day (OR: 4.102 and 95% CI: 1.278- 13.17; p=0.018) were independent predictors of acute kidney injury.

Conclusion

Coronary artery bypass grafting can be performed without any delay after coronary angiography without an increase in the postoperative risk of acute kidney injury in patients with diabetes mellitus.

Perioperative Biomarkers Predicting Postoperative Atrial Fibrillation Risk After Coronary Artery Bypass Grafting: A Narrative Review

Postoperative atrial fibrillation (POAF) after cardiac surgery remains a highly prevalent and costly condition that negatively impacts patient quality of life and survival. Numerous retrospective studies, meta-analysis, and review papers have been reported identifying POAF risk based on patients' risk factors and clinical biomarkers. In this narrative review, the authors report significant variations among selected pre- and perioperative biomarkers used to predict POAF incidence in patients without a history of atrial fibrillation (AF). POAF prediction based on B-type natriuretic peptide, N-terminal pro B-type natriuretic peptide, C-reactive protein, interleukin-6, creatinine, and plasminogen activator inhibitor-1 differs significantly among different studies, thereby limiting their clinical utility to predict POAF risk with high accuracy. Conversely, soluble vascular endothelial cells adhesion molecule-1, soluble CD40 ligand, Galectin-3, and aldosterone show promise for better POAF prediction. However, the current datasets for these selected biomarkers are not of sufficient size to validate the broad clinical application specifically for patients with no prior history of AF.

Prolonged use of noninvasive positive pressure ventilation after extubation among patients in the intensive care unit following cardiac surgery: The predictors and its impact on patient outcome

This retrospective, observational cohort study aimed to determine the independent risk factors and impact of prolonged non-invasive positive pressure ventilation (NIPPV) after extubation among patients in the intensive care unit following cardiac surgery. Patients who received prophylactic NIPPV after extubation were categorized into prolonged (NIPPV duration >3 days, n = 83) and non-prolonged groups (NIPPV duration ≤3 days, n = 105). The perioperative characteristics and hospital outcomes were recorded. The multivariate analyses identified the preoperative residual volume/total lung capacity (RV/TLC) ratio (adjusted odds ratio [AOR]: 1.10; 95% CI:1.01–1.19, p = 0.022) and postoperative acute kidney injury (AKI) with Kidney Disease Improving Global Outcomes (KDIGO) stage 2–3, 48 h after surgery (AOR: 3.87; 95% CI:1.21–12.37, p = 0.023) as independent predictors of prolonged NIPPV. Patients with both RV/TLC ratio > 46.5% and KDIGO stage 2–3 showed a highly increased risk of prolonged NIPPV (HR 27.17, p = 0.010), which was in turn associated with higher risk of postoperative complications and prolonged ICU and hospital stays. Preoperative RV/TLC ratio and postoperative AKI could identify patients at higher risk for prolonged NIPPV associated with poor outcomes. These findings may allow early recognition of patients who are at a higher risk for prolonged NIPPV, and help refine the perioperative management and critical care.

Predictive risk factors of acute kidney injury after on-pump coronary artery bypass grafting

Background

Acute kidney injury (AKI) is a common complication after coronary artery bypass grafting (CABG) and increases the risk of short and long-term morbidity and mortality. The aim of our study is to identify preoperative and intraoperative risk factors for development of AKI after primary isolated on-pump CABG.

Methods

In the retrospective study, 210 consecutive patients who underwent primary isolated on-pump CABG from January 2007 to March 2016 were included. The patients were divided into without AKI group (Group 1) and AKI group (Group 2) after operation. The s-Cr levels were recorded pre and postoperatively. The demographics, preoperative and postoperative data were collected from patient's medical profile and analyzed statistically.

Results

AKI developed in 40.5% of the patients (85 patients out of 210 patients). Age (Group 1; Group 2, 63.7±8.6; 67.2±8.2, P=0.004), body surface area (BSA) (Group 1; Group 2, 1.71±0.16; 1.64±0.16, P=0.003), body weight (Group 1; Group 2, 64.1±10.0; 60.7±10.2, P=0.017) were statistically significant for the development of AKI. However, preoperative hemoglobin, blood urea nitrogen (BUN), creatinine, estimated glomerular filtration rate (eGFR) and C-reactive protein (CRP) were not significant. As intraoperative factors, total pump time (TPT), aortic cross clamp time and transfusion were not significant. Female gender (OR 1.88; P=0.044), preoperative proteinuria (OR 2.711; P=0.011) and emergent operation (OR 2.641; P=0.035) were risk factors in univariate analysis. Preoperative proteinuria (OR 2.396; P=0.035) was only risk factor in multivariate analysis.

Conclusions

Preoperative proteinuria was an independent predictor of postoperative AKI in patients undergoing primary isolated on-pump CABG. The accurate risk prediction of AKI after surgery can help clinicians manage more effectively in high-risk patients.

Transient acute kidney injury after cardiac surgery does not independently affect postoperative outcomes

BACKGROUND

The objective of this study was to assess the incidence of in-hospital acute kidney injury (AKI) after cardiac surgery by comparing preoperative baseline renal function with renal function during the postoperative period and at discharge, and to relate these indices with in-hospital postoperative outcomes.

METHODS

A retrospective analysis was performed over a 4-year period from a series of 426 adult patients. Kidney function was based on serum creatinine (SCr), Cockroft-Gault estimated creatinine clearance (eCrCl), and glomerular filtration rate estimated with the Modification of Diet in Renal Disease formula (eGFR). Baseline values were compared with "peak" values of altered kidney function postoperatively, and "discharge" values. In-hospital mortality and complication rates were compared between patients with transient and persistent AKI, and those without postoperative AKI.

RESULTS

After surgery, AKI (Risk-Injury-Failure-Loss-Endstage [RIFLE] classes Injury and Failure) was diagnosed in 14.6-17.5% of patients based on peak values. AKI diagnosis was reduced to 3.6-4.5% when SCr, eCrCl, and eGFR were measured at discharge. In-hospital mortality of patients with transient AKI was 4% versus 26% in patients with AKI at discharge (odds ratio = 0.11, 95% confidence interval 0.02-0.62, P = 0.011).

CONCLUSIONS

A diagnosis of AKI based on measurements of eGFR during the postoperative period was nearly four times more frequent than the same diagnosis at discharge. Transient AKI was the predominate presentation of postoperative kidney dysfunction in this study. Transient AKI did not affect in-hospital outcomes compared with patients without AKI. Patients with persistent AKI at discharge had the highest mortality.

High central venous pressure is associated with acute kidney injury and mortality in patients underwent cardiopulmonary bypass surgery

PURPOSE

We sought to investigate the relationship between high CVP, AKI, and mortality in patients undergoing cardiac surgery with cardiopulmonary bypass.

MATERIALS

All patients aged 18 years or older who underwent cardiac surgery with CPB were prospectively reviewed. Patients were excluded when renal artery were involved before and during surgery. Patients were dichotomized into high CVP group(>10 mmHg) and low CVP group(<10 mmHg). All patients were followed by telephone.

RESULTS

A total of 1941 patients were included in observed study. In high CVP group, three hundred forty-seven patients (43.32%) developed AKI, while eighty-six (7.543%) in low CVP group(P <0.0001). Furthermore, in every KDIGO stage, patients of AKI in high CVP group were more than those in low CVP group(P <0.0001). The incidence of AKI increased as CVP increased, especially when CVP was higher than 10cmH2O. In a median follow-up time of 9.2 months, Crude mortality is 8.365% in the high CVP group compared to 1.929% in the low CVP group (p<0.0001). In multivariate analysis, CVP remained the independent predictor of survival.

CONCLUSIONS

High CVP is associated with AKI , and it is independently related to all-cause mortality in patients underwent cardiovascular surgery with cardiopulmonary bypass.

Randomized trial of one-hour sodium bicarbonate vs standard periprocedural saline hydration in chronic kidney disease patients undergoing cardiovascular contrast procedures

Background

Guidelines advise periprocedural saline hydration for prevention of contrast induced-acute kidney injury (CI-AKI). We analysed whether 1-hour sodium bicarbonate hydration administered solely prior to intra-arterial contrast exposure is non-inferior to standard periprocedural saline hydration in chronic kidney disease (CKD) patients undergoing elective cardiovascular diagnostic or interventional contrast procedures.

Methods

We performed an open-label multicentre non-inferiority trial between 2011–2014. Patients were randomized to 1 hour pre-procedure sodium bicarbonate hydration (250 ml 1.4%, N = 168) or 4–12 hours saline hydration (1000 ml 0.9%, N = 165) prior to and following contrast administration (2000 ml of saline total). Primary outcome was the relative serum creatinine increase (%) 48–96 hours post contrast exposure. Secondary outcomes were: incidence of CI-AKI (serum creatinine increase>25% or >44μmol/L), recovery of renal function, the need for dialysis, and hospital costs within two months follow-up.

Results

Mean relative creatinine increase was 3.1% (95%CI 0.9 to 5.2%) in the bicarbonate and 1.1% (95%CI -1.2 to 3.5%) in the saline arm, mean difference 1.9% (95%CI -1.2 to 5.1%, p-non-inferiority <0.001). CI-AKI occurred in 11 (6.7%) patients randomized to sodium bicarbonate and 12 (7.5%) to saline (p = 0.79). Renal function did not fully recover in 40.0% and 44.4% of CI-AKI patients, respectively (p = 0.84). No patient required dialysis. Mean costs for preventive hydration and clinical preparation for the contrast procedure were $1158 for sodium bicarbonate vs. $1561 for saline (p < 0.001).

Conclusion

Short hydration with sodium bicarbonate prior to elective cardiovascular diagnostic or therapeutic contrast procedures is non-inferior to standard periprocedural saline hydration in CKD patients with respect to renal safety and results in considerable healthcare savings.

Trial registration

Netherlands Trial Register (http://www.trialregister.nl/trialreg/index.asp), Nr NTR2699

Perioperative risk factors for acute kidney injury after off-pump coronary artery bypass grafting: a retrospective study

Background

Acute kidney injury (AKI) after cardiac surgery is associated with increased morbidity and mortality. Although morbidity of AKI after off-pump coronary artery bypass grafting (OPCAB) has been investigated, little is known about risk factors for AKI after OPCAB. To identify risk factors for AKI, we examined the association between perioperative variables and AKI after OPCAB.

Findings

We reviewed the medical records of consecutive adult patients who underwent isolated OPCAB between January 2010 and February 2013 in a single institute, retrospectively. The primary outcome was the incidence of AKI evaluated using Acute Kidney Injury Network classifications during the first 48 h postoperatively. We investigated preoperative and intraoperative variables, including hemodynamic parameters, as potential risk factors for AKI. The relationship between candidates of AKI and incidence of AKI was examined by multivariate logistic regression analysis.A total of 298 patients were enrolled in this study. Acute kidney injury occurred in 47 patients (15.7%). Multivariate logistic regression analysis showed that intraoperative furosemide administration (odds ratio [OR], 5.163; 95% confidence interval, 2.171 to 12.185; P < 0.001] and diabetes mellitus (OR, 1.954; 95% confidence interval, 1.004 to 3.880; P = 0.049) were significantly associated with AKI.

Conclusions

Intraoperative furosemide administration and diabetes mellitus were significantly associated with AKI in patients who had received OPCAB.

Relation of subclinical serum creatinine elevation to adverse in-hospital outcomes among myocardial infarction patients

BACKGROUND:

Acute kidney injury is associated with adverse outcomes after acute ST elevation myocardial infarction (STEMI). It remains unclear, however, whether subclinical increase in serum creatinine that does not reach the consensus criteria for acute kidney injury is also related to adverse outcomes in STEMI patients undergoing primary percutaneous coronary intervention.

METHODS:

We conducted a retrospective study of 1897 consecutive STEMI patients between January 2008 and May 2016 who underwent primary percutaneous coronary intervention, and in whom acute kidney injury was not diagnosed throughout hospitalization. We investigated the incidence of subclinical acute kidney injury (defined as serum creatinine increase of ≥ 0.1 and < 0.3 mg/dl) and its relation to a composite end point of adverse in hospital outcomes.

RESULTS:

Subclinical acute kidney injury was detected in 321 patients (17%). Patients with subclinical acute kidney injury had increased rate of the composite end point of adverse in-hospital events (20.3% vs. 9.7%, p<0.001), a finding which was independent of baseline renal function. Individual components of this end point (occurrence of heart failure, atrial fibrillation, need for mechanical ventilation and in-hospital mortality) were all significantly higher among patients with subclinical acute kidney injury ( p< 0.05 for all). In a multivariable regression model subclinical acute kidney injury was independently associated with higher risk for adverse in-hospital events (odds ratio 1.92.6, 95% confidence interval: 1.23-2.97, p=0.004).

CONCLUSIONS:

Among STEMI patients treated with primary percutaneous coronary intervention, small, subclinical elevations of serum creatinine, while not fulfilling the consensus criteria for acute kidney injury, may serve as a significant biomarker for adverse outcomes.

Comparison of three early biomarkers for acute kidney injury after cardiac surgery under cardiopulmonary bypass

Background

Acute kidney injury (AKI) is a serious complication after cardiac surgery, being associated with a high mortality. We assessed three urinary biomarkers, L-type fatty acid-binding protein (L-FABP), neutrophil gelatinase-associated lipocalin (NGAL), and angiotensinogen, which are elevated through different mechanisms, and investigated which of these biomarkers was the earliest and most useful indicator of AKI after cardiac surgery.

Methods

This study was a prospective observational study conducted at a single-institution university hospital. All patients were adults aged under 80 years who underwent cardiac surgery with cardiopulmonary bypass between November 2013 and January 2015. Perioperatively, urine samples were obtained from all patients at five points. Based on AKI criteria, patients were divided into two groups: AKI group (n = 11) and non-AKI group (n = 39), according to postoperative serum creatinine (Cr) levels.

Results

Urinary L-FABP, NGAL, angiotensinogen, and Cr were measured perioperatively. L-FABP was significantly higher in the AKI group than in the non-AKI group at the end of surgery and 3 h after surgery. L-FABP levels were 601.5 ± 341.7 and 233.8 ± 127.2 μg/g Cr in the AKI and non-AKI groups, respectively. Three hours after surgery, NGAL levels were 950.5 ± 827.9 and 430.0 ± 250.6 μg/g Cr in the AKI and non-AKI groups, respectively, the level being significantly higher in the AKI group than in the non-AKI group. There were no significant differences in urinary angiotensinogen levels between the two groups at any time point.

Conclusions

We demonstrated the utility of L-FABP and NGAL, but not angiotensinogen in the early recognition of AKI. The problem of the different peak points among biomarkers needs to be resolved for discovery of a panel of biomarkers.

Minor Postoperative Increases of Creatinine Are Associated with Higher Mortality and Longer Hospital Length of Stay in Surgical Patients

BACKGROUND

Surgical patients frequently experience postoperative increases in creatinine levels. The authors hypothesized that even small increases in postoperative creatinine levels are associated with adverse outcomes.

METHODS

The authors examined the association of postoperative changes from preoperative baseline creatinine with all-cause in-hospital mortality and hospital length of stay (HLOS) in a retrospective analysis of surgical patients at a single tertiary care center between January 2006 and June 2012.

RESULTS

The data of 39,369 surgical patients (noncardiac surgery n = 37,345; cardiac surgery n = 2,024) were analyzed. Acute kidney injury (AKI)-by definition of the Kidney Disease: Improving Global Outcome group-was associated with a five-fold higher mortality (odds ratio [OR], 4.8; 95% CI, 4.1 to 5.7; P < 0.001) and a longer HLOS of 5 days (P < 0.001) after adjusting for age, sex, comorbidities, congestive heart failure, preoperative hemoglobin, preoperative creatinine, exposure to radiocontrast agent, type of surgery, and surgical AKI risk factors. Importantly, even minor creatinine increases (Δcreatinine 25 to 49% above baseline but < 0.3 mg/dl) not meeting AKI criteria were associated with a two-fold increased risk of death (OR, 1.7; 95% CI, 1.3 to 2.4; P < 0.001) and 2 days longer HLOS (P < 0.001). This was more pronounced in noncardiac surgery patients. Patients with minor creatinine increases had a five-fold risk of death (OR, 5.4; 95% CI, 1.5 to 20.3; P < 0.05) and a 3-day longer HLOS (P < 0.01) when undergoing noncardiac surgery.

CONCLUSIONS

Even minor postoperative increases in creatinine levels are associated with adverse outcomes. These results emphasize the importance to find effective therapeutic approaches to prevent or treat even mild forms of postoperative kidney dysfunction to improve surgical outcomes.

The predictive value of s-cystatin C for mortality after coronary artery bypass surgery

OBJECTIVES

To evaluate serum creatinine (s-creatinine) and serum cystatin C (s-cystatin C) levels and estimated glomerular filtration rate (eGFR) at different time points as predictors for mortality in patients undergoing coronary artery bypass grafting (CABG).

METHODS

A total of 1638 patients undergoing elective CABG were studied prospectively over a median follow-up of 3.5 years (range, 2.0-5.0 years). Renal function was assessed by a comparison of s-creatinine, s-cystatin C values measured preoperatively and at the lowest postoperative level of renal function. The eGFR was estimated by different formulas: Modification of Diet in Renal Disease, the 2009 Chronic Kidney Disease Epidemiology (CDK-EPI) for s-creatinine, the 2012 CKD-EPI formula for s-cystatin C, the 2012 CKD-EPI formula for s-cystatin C and s-creatinine in combination, and the Caucasian Asian, Pediatric, and Adult subjects formula for s-cystatin C. Cox proportional hazards model analysis and C-statistics were used to evaluate independent predictors of mortality and to assess the predictive ability of the different renal function measures.

RESULTS

The 30-day mortality was 0.8%. Overall survival was 96.1% ± 0.4% at 2 years and 90.0% ± 1.2% at 5 years. Preoperative s-cystatin C showed greater predictive power than s-creatinine for overall mortality (area under the curve, 0.794 vs 0.653). Preoperative s-cystatin C (hazard ratio [HR], 1.65; 95% confidence interval [CI], 1.36-1.99) and eGFR based on s-cystatin C (HR, 0.96; 95% CI, 0.95-0.98), were both independent predictors of mortality. The unadjusted HR for mortality comparing the lowest preoperative cystatin C quintile (Q1) with Q4-Q5 were as follows: Q1 versus Q5, HR, 2.0; 95% CI, 1.6-2.5 (P < .001); Q1 versus Q4, HR, 1.6; 95% CI, 1.2-2.2 (P = .005).

CONCLUSIONS

The s-cystatin C level and s-cystatin C-based eGFR measured preoperatively are strong predictors for mortality after elective CABG.

Acute Kidney Injury in Cardiorenal Syndrome Type 1 Patients: A Systematic Review and Meta-Analysis

BACKGROUND

We evaluated the epidemiology and outcome of acute kidney injury (AKI) in patients with cardiorenal syndrome type 1 (CRS-1) and its subgroups: acute heart failure (AHF), acute coronary syndrome (ACS) and after cardiac surgery (CS).

SUMMARY

We performed a systematic review and meta-analysis. CRS-1 was defined by AKI (based on RIFLE, AKIN and KDIGO), worsening renal failure (WRF) and renal replacement therapy (RRT). We investigated the three most common clinical causes of CRS-1: AHF, ACS and CS. Out of 332 potential papers, 64 were eligible - with AKI used in 41 studies, WRF in 25 and RRT in 20. The occurrence rate of CRS-1, defined by AKI, WRF and RRT, was 25.4, 22.4 and 2.6%, respectively. AHF patients had a higher occurrence rate of CRS-1 compared to ACS and CS patients (AKI: 47.4 vs. 14.9 vs. 22.1%), but RRT was evenly distributed among the types of acute cardiac disease. AKI was associated with an increased mortality rate (risk ratio = 5.14, 95% CI 3.81-6.94; 24 studies and 35,227 patients), a longer length of stay in the intensive care unit [LOSICU] (median duration = 1.37 days, 95% CI 0.41-2.33; 9 studies and 10,758 patients) and a longer LOS in hospital [LOShosp] (median duration = 3.94 days, 95% CI 1.74-6.15; 8 studies and 35,227 patients). Increasing AKI severity was associated with worse outcomes. The impact of CRS-1 defined by AKI on mortality was greatest in CS patients. RRT had an even greater impact compared to AKI (mortality risk ratio = 9.2, median duration of LOSICU = 10.6 days and that of LOShosp = 20.2 days).

KEY MESSAGES

Of all included patients, almost one quarter developed AKI and approximately 3% needed RRT. AHF patients experienced the highest occurrence rate of AKI, but the impact on mortality was greatest in CS patients.

Type 1 and type 2 diabetes mellitus and risk of acute kidney injury after coronary artery bypass grafting

BACKGROUND

Our objective was to investigate the association between type 1 diabetes mellitus (T1DM), type 2 diabetes mellitus (T2DM), and acute kidney injury (AKI) in patients who underwent coronary artery bypass grafting (CABG).

METHODS

We included all patients (n = 36,106) from the SWEDEHEART register who underwent primary isolated CABG in Sweden from 2003 to 2013. Information on type of diabetes was retrieved from the Swedish National Diabetes Register. Acute kidney injury was defined as an absolute increase by 0.3 mg/dL (26 μmol/L) or a relative increase by at least 50% in postoperative serum creatinine compared with preoperative levels. Odds ratios with 95% CIs for AKI in patients with T1DM and T2DM were compared with those patients without diabetes using logistic regression.

RESULTS

In total, there were 457 patients (1.3%) with T1DM and 5124 (14%) with T2DM. Among patients with T1DM and T2DM, 145 (32%) and 1037 (20%), respectively, developed AKI, compared with 4017 (13%) in patients without diabetes. The adjusted odds ratio for AKI was 4.89 (95% CI 3.82-6.25) in patients with T1DM and 1.27 (95% CI 1.16-1.40) in patients with T2DM, in comparison with patients without diabetes.

CONCLUSIONS

Both T1DM and T2DM were associated with an increased risk of AKI after CABG. The risk was markedly higher in patients with T1DM than in those with T2DM and was independent of preoperative renal function.

Risk factors for mortality of patients undergoing coronary artery bypass graft surgery

Introduction

Coronary artery bypass grafting is a safe procedure performed worldwide with low rates of mortality and morbidity in general population.

Objective

To investigate risk factors for mortality of patients undergoing coronary artery bypass grafting coronary artery bypass grafting surgery.

Methods

A total of 1,628 consecutive patients undergoing on-pump coronary artery bypass grafting were retrospectively studied from December 1999 to February 2012. Data analysis involved paired Student t test, Mann-Whitney test and Fisher’s exact test for the categorical data. Logistic regression, Odds Ratio and 95%CI were used for definition of risk factors for mortality.

Results

Of a total of 1,628 patients undergoing on-pump coronary artery bypass grafting, 141 (8.7%) died. The following risk factors for mortality were identified after logistic regression: dialysis (OR=7.61; 95%CI 3.58-16.20), neurologic dysfunction type I (OR=4.42; 95%CI 2.48-7.81), use of IABP (OR=3.38; 95%CI 1.98-5.79), cardiopulmonary bypass time (OR=3.09; 95%CI 2.04-4.68), serum creatinine on admission and peak values > 0.4mg/dL (OR=2.67; 95%CI 1.79-4.00), age > 65 years (OR=2.31; 95%CI 1.55-3.44), and time between hospital admission and and surgical procedure (OR=1.53; 95%CI 1.03-2.27).

Conclusion

Dialysis, type I neurologic dysfunction, use of IABP, cardiopulmonary bypass time (> 115 minutes), serum creatinine on admission and peak values>0.4mg/dL, age > 65 years and time between hospital admission and surgical procedure were considered as risk factors for mortality in patients undergoing on-pump coronary artery bypass grafting surgery.

Clinical SYNTAX Score Can Predict Acute Kidney Injury following On-Pump but Not Off-Pump Coronary Artery Bypass Surgery

BACKGROUND

The complexity of coronary artery disease is usually a neglected factor in risk stratification systems. We aimed to analyze the discriminative ability of the clinical SYNTAX score (CSS) for acute kidney injury (AKI) following on- and off-pump coronary artery surgery.

METHODS

A total of 193 patients were reviewed in this study. Patients were divided into two groups according to the surgical procedure (group I: off-pump coronary artery bypass grafting, n = 89; group II: on-pump coronary artery bypass grafting, n = 104). Preoperative demographic data, the CSS and postoperative renal functions were evaluated. The postoperative AKI classification was made using the RIFLE (Risk, Injury, Failure, Loss of function, and End-stage renal disease) criteria.

RESULTS

Postoperative AKI occurred in 14 of 89 patients (15.7%) in group I and in 29 of 104 patients in group II (27.8%; p = 0.046). The CSS did not vary much between the groups (31.52 ± 13.08 vs. 29.89 ± 15.70; p = 0.638). In group I, the CSS was not different between patients with AKI and those without AKI (30.167 ± 3.93 vs. 31.91± 14.75; p = 0.78). In group II, the CSS was 36.85 ± 18.33 in patients with AKI and 28.02 ± 12.32 in those without, and the difference was significant (p = 0.02). The discriminative ability of the CSS for postoperative AKI using the AUC analysis was 0.500 in group I and 0.840 in group II.

CONCLUSION

The CSS may be a simple and successful means of risk prediction of postoperative AKI in on-pump coronary artery surgery.

Acute kidney injury based on KDIGO (Kidney Disease Improving Global Outcomes) criteria in patients with elevated baseline serum creatinine undergoing cardiac surgery

INTRODUCTION

Preoperatively elevated serum creatinine (SCr) is considered an independent risk factor for morbidity and mortality after cardiac surgery. The aim of this study was to apply the Kidney Disease Improving Global Outcomes classification for acute kidney injury in a population of patients with preoperatively elevated serum creatinine who underwent cardiac surgery (coronary artery bypass grafting or cardiac valve surgery) and to evaluate the acute worsening of renal function as a predictor of 30-day mortality.

METHODS

This was a single-center retrospective study that included patients from the Postoperative Cardiac Surgery Intensive Care Unit of the Hospital de Base, São José do Rio Preto Medical School. Demographics, type of surgery, laboratory data and pre, peri and postoperative data were obtained from a prospectively collected database. From January 2003 to June 2013, 2,878 patients underwent cardiac surgery, either coronary artery bypass grafting or cardiac valve surgery, at the Hospital de Base of São José do Rio Preto Medical School. Out of those, 918 showed elevated preoperative serum creatinine, with SCr > 1.30 mg/dL for men and > 1.00 mg/dL for women. Five hundred and forty nine patients (60%) undergoing coronary artery bypass grafting and 369 patients (40%) undergoing cardiac valve surgery. A Multivariate Cox Proportional Hazard Model (stepwise) was used to assess the relationship between AKI and mortality at 30 days.

RESULTS

Out of the 918 patients studied, 391 (43%) had postoperative AKI: 318 (35%) had Kidney Disease Improving Global Outcomes stage 1, 27 (2.9%) had Kidney Disease Improving Global Outcomes stage 2, and 46 (5.0%) had Kidney Disease Improving Global Outcomes stage 3. Patients in every stage of acute kidney injury showed progressive increase in EuroSCORE values, 30-day mortality rates, cardiopulmonary bypass duration, and intensive care length of stay. Among patients classified as Kidney Disease Improving Global Outcomes stage 3, 76% required dialysis with a 30-day mortality of 66%. The Cox proportional hazards model showed that the hazard ratio for 30-day mortality was 4.8 for Kidney Disease Improving Global Outcomes stage 1 patients, 13.5 for Kidney Disease Improving Global Outcomes stage 2 patients, and 20.8 for Kidney Disease Improving Global Outcomes stage 3 patients (P<0.001 for all). Subgroup analyses (coronary artery bypass grafting and cardiac valve surgery) had similar results.

CONCLUSION

In this population, acute kidney injury based on the Kidney Disease Improving Global Outcomes criteria was a powerful predictor of 30-day mortality in patients with elevated preoperative serum creatinine who underwent cardiac surgery (coronary artery bypass grafting or cardiac valve surgery).

Neutrophil gelatinase-associated lipocalin combined with delta serum creatinine provides early risk stratification for adverse outcomes after cardiac surgery: a prospective observational study

OBJECTIVES

Novel biomarkers of renal injury appear inconsistent in identifying a creatinine-based diagnosis of acute kidney injury. To be clinically useful, novel acute kidney injury biomarkers should identify patients at increased risk for adverse outcomes that are a consequence of acute kidney injury earlier and with greater utility than conventional creatinine-based metrics. We sought to determine the prognostic utility of both urinary neutrophil gelatinase-associated lipocalin and varying creatinine-based metrics of renal injury at multiple time points associated with cardiac surgery.

DESIGN

Prospective observational study.

SETTING

Academic medical center.

PATIENTS

Six hundred three adults undergoing cardiac surgery.

INTERVENTIONS

Nil.

MEASUREMENTS AND MAIN RESULTS

Urinary neutrophil gelatinase-associated lipocalin was measured at baseline and again less than 1 hour, 3 hours, and 18-24 hours after separation from cardiopulmonary bypass. Creatinine-based metrics included a Kidney Disease: Improving Global Outcomes definition of acute kidney injury through 7 days postoperatively as well as ΔSCr-initial, defined as the incremental change in SCr from baseline to first postoperative measure. Multivariable regression determined the prognostic utility of neutrophil gelatinase-associated lipocalin and creatinine, alone and in combination, for the primary composite outcome of hospital mortality or renal replacement therapy. The primary outcome occurred in 25 patients. Adjusted for covariates ΔSCr-initial greater than or equal to 0.0 mg/dL provided early prognostic utility for the primary outcome (odds ratio, 8.9; 95% CI, 3.0-26.6), the odds ratio comparable to a creatinine-based Kidney Disease: Improving Global Outcomes definition of acute kidney injury applied over 7 days postoperatively. The upper quartile of urinary neutrophil gelatinase-associated lipocalin best predicted the primary outcome when measured 18-24 hours post-cardiopulmonary bypass (odds ratio, 18.6; 95% CI, 5.1-68.4; p = 0.001) with earlier post-cardiopulmonary bypass measures of uncertain utility. Combining both ΔSCr-initial and neutrophil gelatinase-associated lipocalin measured 3 hours after cardiopulmonary bypass provided excellent early risk stratification for the primary outcome (odds ratio, 18.3; 95% CI, 4.5-75.0).

CONCLUSIONS

Combining urinary neutrophil gelatinase-associated lipocalin with a novel creatinine-based metric, both available soon after completion of surgery, may provide previously unavailable early and effective risk stratification for serious adverse outcomes after cardiac surgery.

Prognostic value of acute kidney injury after cardiac surgery according to kidney disease: improving global outcomes definition and staging (KDIGO) criteria

Objectives

The definition of acute renal failure has been recently reviewed, and the term acute kidney injury (AKI) was proposed to cover the entire spectrum of the syndrome, ranging from small changes in renal function markers to dialysis needs. This study was aimed to evaluate the incidence, morbidity and mortality associated with AKI (based on KDIGO criteria) in patients after cardiac surgery (coronary artery bypass grafting or cardiac valve surgery) and to determine the value of this feature as a predictor of hospital mortality (30 days).

Methods

From January 2003 to June 2013, a total of 2,804 patients underwent cardiac surgery in our service. Cox proportional hazard models were used to determine the association between the development of AKI and 30-day mortality.

Results

A total of 1,175 (42%) patients met the diagnostic criteria for AKI based on KDIGO classification during the first 7 postoperative days: 978 (35%) patients met the diagnostic criteria for stage 1 while 100 (4%) patients met the diagnostic criteria for stage 2 and 97 (3%) patients met the diagnostic criteria for stage 3. A total of 63 (2%) patients required dialysis treatment. Overall, the 30-day mortality was 7.1% (2.2%) for patients without AKI and 8.2%, 31% and 55% for patients with AKI at stages 1, 2 and 3, respectively. The KDIGO stage 3 patients who did not require dialysis had a mortality rate of 41%, while the mortality of dialysis patients was 62%. The adjusted Cox regression analysis revealed that AKI based on KDIGO criteria (stages 1–3) was an independent predictor of 30-day mortality (P<0.001 for all. Hazard ratio = 3.35, 11.94 and 24.85).

Conclusion

In the population evaluated in the present study, even slight changes in the renal function based on KDIGO criteria were considered as independent predictors of 30-day mortality after cardiac surgery.

Impact of cardiopulmonary bypass on acute kidney injury following coronary artery bypass grafting: a matched pair analysis

BACKGROUND

Postoperative Acute Kidney Injury (AKI) after coronary artery bypass grafting (CABG) is a common complication associated with significant morbidity and mortality. Cardiopulmonary bypass (CPB) is accepted to contribute to the occurrence of AKI and is of particular importance as it can be avoided by using the off-pump technique. However the renoprotective properties of off-pump (CABG) are controversial. This analysis evaluates the impact of cardiopulmonary bypass on renal function.

METHODS

A matched-pair analysis of 1428 patients undergoing coronary artery bypass grafting was conducted. The patients were stratified according to their preoperative renal function and to risk factors for postoperative AKI. The development of the glomerular filtration rate (GFR) from before surgery until hospital discharge was analyzed. Incidence of AKI were analyzed. Furthermore the impact of CPB duration on postoperative GFR was assessed.

RESULTS

The occurrence of AKI increases the risk of thirty-day mortality (odds ratio of 4.3). The postoperative GFR decreases significantly after coronary artery bypass grafting but does not differ between onpump and offpump CABG (60.2 ± 24.5 vs 60.7 ± 24.8; p=0.54). No difference regarding the incidence (26.6% vs 25%) and severity of AKI between cardiopulmonary bypass and the off-pump technique could be found. Duration of cardiopulmonary bypass does not correlate with the decline in postoperative glomerular filtration rate (Pearson Product Moment Correlation; p>0.050).

CONCLUSION

Neither the mere use nor duration of cardiopulmonary bypass proofed to be a risk factor for developing postoperative AKI in CABG patients with a comparable preoperative risk profile for postoperative renal dysfunction. Furthermore, the severity of postoperative AKI is not affected by the use of cardiopulmonary bypass.

Minimal changes in postoperative creatinine values and early and late mortality and cardiovascular events after coronary artery bypass grafting

Acute kidney injury (AKI) after coronary artery bypass grafting (CABG) is associated with adverse outcomes. This study investigated if already a minimal change of 0 to 0.3 mg/dl in postoperative serum creatinine values was associated with early death and long-term cardiovascular outcomes and death. From the SWEDEHEART registry, we included 25,686 patients who underwent elective, isolated, primary CABG in Sweden from 2000 to 2008. AKI was categorized according to increases in postoperative creatinine values: group 1, 0 to 0.3 mg/dl; group 2, 0.3 to 0.5 mg/dl; and group 3, >0.5 mg/dl. The primary outcome measure was death from any cause. During a mean follow-up of 6 years, there were 4,350 deaths (17%) and 7,095 hospitalizations (28%) for myocardial infarction, stroke, heart failure, or death (secondary outcome). The adjusted odds ratios (95% confidence interval [CI]) for early mortality in AKI groups 1 to 3 were 1.37 (0.84 to 2.21), 3.64 (2.07 to 6.38), and 15.4 (9.98 to 23.9), respectively. For long-term mortality, the corresponding hazard ratios (95% CI) were 1.07 (1.00 to 1.15), 1.33 (1.19 to 1.48), and 2.11 (1.92 to 2.32), respectively. There was a significant association between each AKI group and the composite outcome (HR 1.09, 95% CI 1.03 to 1.15; HR 1.39, 95% CI 1.27 to 1.52; and HR 1.99, 95% CI 1.84 to 2.16, respectively). In conclusion, already a minimal increase in the postoperative serum creatinine level after CABG was independently associated with long-term all-cause mortality and cardiovascular outcomes, regardless of preoperative renal function.

COMT-Val158Met-polymorphism is not a risk factor for acute kidney injury after cardiac surgery

BACKGROUND

Cardiac surgery-associated acute kidney injury (CSA-AKI) depicts a major complication after cardiac surgery using cardiopulmonary bypass (CPB).

OBJECTIVE

CSA-AKI has clearly been linked to increased perioperative morbidity and mortality. Dysregulations of vasomotor tone are assumed to be causal for CSA-AKI. While catechol-O-methyltransferase (COMT) is involved in metabolizing catecholamines, a single-nucleotide polymorphism (SNP) in the COMT gene leads to different enzyme activities according to genotype. Pilot studies found associations between those COMT genotypes and CSA-AKI.

METHODS

We prospectively included 1741 patients undergoing elective cardiac surgery using cardiopulmonary bypass (CPB). Patients were genotyped for COMT-Val158Met-(G/A) polymorphism (rs4680).

RESULTS

Demographic characteristics and procedural data revealed no significant differences between genotypes. No association between COMT genotypes and the RIFLE criteria could be detected. A multiple linear regression analysis for postoperative creatinine increase revealed highly significant associations for aortic cross-clamp time (P < 0.001), CPB time (P < 0.001), norepinephrine (P < 0.001), and age (P < 0.001). No associations were found for COMT genotypes or baseline creatinine. With an R (2) = 0.39 and a sample size of 1741, the observed power of the regression analysis was >99%.

CONCLUSIONS

Based on our results, we can rule out an association between the COMT-Val158Met-(G/A) polymorphism and the appearance of CSA-AKI.