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

Internal and External Validation of Machine Learning Models for Predicting Acute Kidney Injury Following Non-Cardiac Surgery Using Open Datasets

This study developed and validated a machine learning model to accurately predict acute kidney injury (AKI) after non-cardiac surgery, aiming to improve patient outcomes by assessing its clinical feasibility and generalizability. We conducted a retrospective cohort study using data from 76,032 adults who underwent non-cardiac surgery at a single tertiary medical center between March 2019 and February 2021, and used data from 5512 patients from the VitalDB open dataset for external model validation. The predictive variables for model training consisted of demographic, preoperative laboratory, and intraoperative data, including calculated statistical values such as the minimum, maximum, and mean intraoperative blood pressure. When predicting postoperative AKI, our gradient boosting machine model incorporating all the variables achieved the best results, with AUROC values of 0.868 and 0.757 for the internal and external validations using the VitalDB dataset, respectively. The model using intraoperative data performed best in internal validation, while the model with preoperative data excelled in external validation. In this study, we developed a predictive model for postoperative AKI in adult patients undergoing non-cardiac surgery using preoperative and intraoperative data, and external validation demonstrated the efficacy of open datasets for generalization in medical artificial modeling research.

Cardiopulmonary bypass management and acute kidney injury in cardiac surgery patients

BACKGROUND

Cardiopulmonary bypass (CPB) ensures tissue oxygenation during cardiac surgery. New technology allows continuous registration of CPB variables during the operation. The aim of the present investigation was to study the association between CPB management and the risk of postoperative acute kidney injury (AKI).

METHODS

This observational study based on prospectively registered data included 2661 coronary artery bypass grafting and/or valve patients operated during 2016-2020. Individual patient characteristics and postoperative outcomes collected from the SWEDEHEART registry were merged with CPB variables automatically registered every 20 s during CPB. Associations between CPB variables and AKI were analyzed with multivariable logistic regression models adjusted for patient characteristics.

RESULTS

In total, 387 patients (14.5%) developed postoperative AKI. After adjustments, longer time on CPB and aortic cross-clamp, periods of compromised blood flow during aortic cross-clamp time, and lower nadir hematocrit were associated with the risk of AKI, while mean blood flow, bladder temperature, central venous pressure, and mixed venous oxygen saturation were not. Patient characteristics independently associated with AKI were advanced age, higher body mass index, hypertension, diabetes mellitus, atrial fibrillation, lower left ventricular ejection fraction, estimated glomerular filtration rate <60 or >90 mL/min/m2 , and preoperative hemoglobin concentration below or above the normal sex-specific range.

CONCLUSIONS

To reduce the risk of AKI after cardiac surgery, aortic clamp time and CPB time should be kept short, and low hematocrit and periods of compromised blood flow during aortic cross-clamp time should be avoided if possible.

Prevalence, risk factors, and outcomes of acute kidney injury in a pediatric cardiac intensive care unit: A cross-sectional study

Background and Aims

Acute kidney injury (AKI) is a common complication in pediatric cardiac intensive care unit (CICU). This study aims to identify the prevalence, risk factors, and outcomes of AKI in pediatrics admitted to a CICU unit of a tertiary hospital.

Methods

We retrospectively gathered the data of 253 randomly selected patients admitted to the CICU unit from March 2018 to March 2022. Data were collected from EHRs. We used the Kidney Disease Improving Global Outcomes (KDIGO) criteria for identifying AKI in patients.

Results

Overall, AKI prevalence was 22.9% in our population. In the multivariable analysis, vancomycin intake (odds ratio [OR]: 2.109, 95% confidence interval [CI]: 1.15-3.84), angiography (OR: 4.38, 95% CI: 1.28-14.93), and mechanical ventilation (OR: 2.08, 95% CI: 1.02-4.23) were independent risk factors of AKI development and patients with AKI had a higher in-hospital mortality rate (OR: 5.81, 95% CI: 2.55-13.19), higher need for cardiopulmonary resuscitation (OR: 3.08, 95% CI: 1.17-8.09), and longer ICU length of stay (OR: 6.49, 95% CI: 3.31-9.67). Furthermore, furosemide administration was associated with lower risk of developing AKI (OR: 0.52, 95% CI: 0.27-0.97).

Conclusion

AKI is common and is associated with worse outcomes in patients with congenital heart disease. Our results emphasize the importance of early identification and monitoring of AKI in the pediatric CICU setting.

Development and external validation of multimodal postoperative acute kidney injury risk machine learning models

Objectives

To develop and externally validate machine learning models using structured and unstructured electronic health record data to predict postoperative acute kidney injury (AKI) across inpatient settings.

Materials and Methods

Data for adult postoperative admissions to the Loyola University Medical Center (2009-2017) were used for model development and admissions to the University of Wisconsin-Madison (2009-2020) were used for validation. Structured features included demographics, vital signs, laboratory results, and nurse-documented scores. Unstructured text from clinical notes were converted into concept unique identifiers (CUIs) using the clinical Text Analysis and Knowledge Extraction System. The primary outcome was the development of Kidney Disease Improvement Global Outcomes stage 2 AKI within 7 days after leaving the operating room. We derived unimodal extreme gradient boosting machines (XGBoost) and elastic net logistic regression (GLMNET) models using structured-only data and multimodal models combining structured data with CUI features. Model comparison was performed using the receiver operating characteristic curve (AUROC), with Delong's test for statistical differences.

Results

The study cohort included 138 389 adult patient admissions (mean [SD] age 58 [16] years; 11 506 [8%] African-American; and 70 826 [51%] female) across the 2 sites. Of those, 2959 (2.1%) developed stage 2 AKI or higher. Across all data types, XGBoost outperformed GLMNET (mean AUROC 0.81 [95% confidence interval (CI), 0.80-0.82] vs 0.78 [95% CI, 0.77-0.79]). The multimodal XGBoost model incorporating CUIs parameterized as term frequency-inverse document frequency (TF-IDF) showed the highest discrimination performance (AUROC 0.82 [95% CI, 0.81-0.83]) over unimodal models (AUROC 0.79 [95% CI, 0.78-0.80]).

Discussion

A multimodality approach with structured data and TF-IDF weighting of CUIs increased model performance over structured data-only models.

Conclusion

These findings highlight the predictive power of CUIs when merged with structured data for clinical prediction models, which may improve the detection of postoperative AKI.

Impact of Chronic Kidney Disease on Clinical Outcomes during Hospitalization and Five-Year Follow-Up after Coronary Artery Bypass Grafting

Background

Chronic kidney disease (CKD) is often associated with multiple comorbidities including diabetes mellitus, and each has its own complications and impact after cardiac surgery including coronary revascularization. The objective of this work was to study the impact of CKD on clinical outcomes after coronary artery bypass grafting (CABG) and to compare outcomes in patients with different grades of renal functions. We retrospectively reviewed all patients who underwent CABG from January 2016 to August 2020 at our tertiary care hospital using electronic medical records.

Results

The study included 410 patients with a median age of 60 years, and 28.6% of them had CKD and hospital mortality of 2.7%. About 71.4% of the patients had GFR > 60 mL/min per 1.73 m2, 18.1% had early CKD (GFR 30-60), 2.7% had late CKD (GFR < 30), and 7.8% of them had end-stage renal disease (ESRD) requiring dialysis. The CKD group had significantly more frequent hospital mortality (p = 0.04), acute cerebrovascular stroke (p = 0.03), acute kidney injury (AKI) (p < 0.001), longer ICU stay (p = 0.002), post-ICU stay (p = 0.001), and sternotomy wound debridement (p = 0.03) compared to the non-CKD group. The frequencies of new need for dialysis were 2.4% vs. 14.9% vs. 45.5% (p < 0.001) in the patients with GFR > 60 mL/min per 1.73 m2, early CKD, and late CKD, respectively. Acute cerebral stroke (OR: 10.29, 95% CI: 1.82-58.08, and p = 0.008), new need for dialysis (OR: 25.617, 95% CI: 13.78-85.47, and p < 0.001), and emergency surgery (OR: 3.1, 95% CI: 1.82-12.37, and p = 0.036) were the independent predictors of hospital mortality after CABG. The patients with CKD had an increased risk of strokes (HR: 2.14, 95% CI: 1.20-3.81, and p = 0.01) but insignificant mortality increase (HR: 1.44, 95% CI: 0.42-4.92, and p = 0.56) during follow-up.

Conclusion

The patients with CKD, especially the late grade, had worse postoperative early and late outcomes compared to non-CKD patients after CABG. Patients with dialysis-independent CKD had increased risks of needing dialysis, hospital mortality, and permanent dialysis after CABG.

Prediction of acute kidney injury risk after cardiac surgery: using a hybrid machine learning algorithm

Background

Acute kidney injury (AKI) is a serious complication after cardiac surgery. We derived and internally validated a Machine Learning preoperative model to predict cardiac surgery-associated AKI of any severity and compared its performance with parametric statistical models.

Methods

We conducted a retrospective study of adult patients who underwent major cardiac surgery requiring cardiopulmonary bypass between November 1st, 2009 and March 31st, 2015. AKI was defined according to the KDIGO criteria as stage 1 or greater, within 7 days of surgery. We randomly split the cohort into derivation and validation datasets. We developed three AKI risk models: (1) a hybrid machine learning (ML) algorithm, using Random Forests for variable selection, followed by high performance logistic regression; (2) a traditional logistic regression model and (3) an enhanced logistic regression model with 500 bootstraps, with backward variable selection. For each model, we assigned risk scores to each of the retained covariate and assessed model discrimination (C statistic) and calibration (Hosmer–Lemeshow goodness-of-fit test) in the validation datasets.

Results

Of 6522 included patients, 1760 (27.0%) developed AKI. The best performance was achieved by the hybrid ML algorithm to predict AKI of any severity. The ML and enhanced statistical models remained robust after internal validation (C statistic = 0.75; Hosmer–Lemeshow p = 0.804, and AUC = 0.74, Hosmer–Lemeshow p = 0.347, respectively).

Conclusions

We demonstrated that a hybrid ML model provides higher accuracy without sacrificing parsimony, computational efficiency, or interpretability, when compared with parametric statistical models. This score-based model can easily be used at the bedside to identify high-risk patients who may benefit from intensive perioperative monitoring and personalized management strategies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12911-022-01859-w.

Elevated Levels of Urinary Biomarkers TIMP-2 and IGFBP-7 Predict Acute Kidney Injury in Neonates after Congenital Heart Surgery

Objectives  This article investigated the utility of urine biomarkers tissue inhibitor of metalloproteinase-2 (TIMP-2) and insulin-like growth factor binding protein-7 (IGFBP-7) in identifying acute kidney injury (AKI) in neonates after congenital heart surgery (CHS). TIMP-2 and IGFBP-7 are cell cycle arrest proteins detected in urine during periods of kidney stress/injury. Methods  We conducted a single-center, prospective study between September 2017 and May 2019 with neonates undergoing CHS requiring cardiopulmonary bypass (CPB). Urine samples were analyzed using NephroCheck prior to surgery and 6, 12, 24, and 96 hours post-CPB. All patients were evaluated using the Acute Kidney Injury Network (AKIN) criteria. Wilcoxon rank sum tests were used to compare the medians of the [TIMP-2*IGFBP-7] values in the AKIN negative and positive groups at each time point. Receiver operating characteristic curves were used to measure how well the [TIMP-2*IGFBP-7] values predict AKIN status. Results  Thirty-six patients were included. No patients met the AKIN criteria for AKI preoperatively. Postoperatively, 19 patients (53%) met the AKIN criteria for AKI diagnosis: 13 (36%) stage 1, 5 (14%) stage 2, and 1 (3%) stage 3. None required renal replacement therapy. At the 24-hour time points, patients who met the AKIN criteria for AKI had a statistically significantly higher [TIMP-2*IGFBP7] values than the patients without AKI (1.1 vs. 0.27 [ng/mL] ² /1,000) at 24 hours (adj- p  = 0.0019). Conclusion  AKI is a serious complication associated with adverse outcomes in patients undergoing cardiac surgery. [TIMP-2*IGFBP-7] urinary level 24 hours after CPB is a good predictor of AKI in this population.

Rationale and Design of Assessing the Effectiveness of Short-Term Low-Dose Lithium Therapy in Averting Cardiac Surgery-Associated Acute Kidney Injury: A Randomized, Double Blinded, Placebo Controlled Pilot Trial

Background: Burgeoning pre-clinical evidence suggests that therapeutic targeting of glycogen synthase kinase 3β (GSK3β), a convergence point of multiple cellular protective signaling pathways, confers a beneficial effect on acute kidney injury (AKI) in experimental models. However, it remains unknown if GSK3β inhibition likewise mitigates AKI in humans. Cardiac surgery associated acute kidney injury (CSA-AKI) poses a significant challenge for clinicians and currently the only treatment available is general supportive measures. Lithium, an FDA approved mood stabilizer, is the best-known GSK3β inhibitor and has been safely used for over half a century as the first line regimen to treat bipolar affective disorders. This study attempts to examine the effectiveness of short term low dose lithium on CSA-AKI in human patients.

Methods/Design: This is a single center, prospective, randomized, double blinded, placebo controlled pilot study on patients undergoing cardiac surgery with cardiopulmonary bypass. Patients will be randomized to receive a small dose of lithium or placebo treatment for three consecutive days. Renal function will be measured via creatinine as well as novel AKI biomarkers. The primary outcome is incidence of AKI according to Acute Kidney Injury Network (AKIN) criteria, and secondary outcomes include receipt of new dialysis, days on dialysis, days on mechanical ventilation, infections within 1 month of surgery, and death within 90 days of surgery.

Discussion: As a standard selective inhibitor of GSK3β, lithium has been shown to exert a beneficial effect on tissue repair and regeneration upon acute injury in multiple organ systems, including the central nervous system and hematopoietic system. In experimental AKI, lithium at small doses is able to ameliorate AKI and promote kidney repair. Successful completion of this study will help to assess the effectiveness of lithium in CSA-AKI and could potentially pave the way for large-scale randomized trials to thoroughly evaluate the efficacy of this novel regimen for preventing AKI after cardiac surgery.

Trial Registration: This study was registered prospectively on the 17th February 2017 at ClinicalTrials.gov (NCT03056248, https://clinicaltrials.gov/ct2/show/NCT03056248?term=NCT03056248&draw=2&rank=1).

Predicting the Risk of Acute Kidney Injury in Patients After Percutaneous Coronary Intervention (PCI) or Cardiopulmonary Bypass (CPB) Surgery: Development and Assessment of a Nomogram Prediction Model

Background

We sought to create a model that incorporated ultrasound examinations to predict the risk of acute kidney injury (AKI) after percutaneous coronary intervention (PCI) or cardiopulmonary bypass (CPB) surgery.

Material/Methods

A total of 292 patients with AKI after PCI or CPB surgery were enrolled for the study. Afterwards, treatment-related information, including data pertaining to ultrasound examination, was collected. A random forest model and multivariate logistic regression analysis were then used to establish a predictive model for the risk of AKI. Finally, the predictive quality and clinical utility of the model were assessed using calibration plots, receiver-operating characteristic curve, C-index, and decision curve analysis.

Results

Predictive factors were screened and the model was established with a C-index of 0.955 in the overall sample set. Additionally, an area under the curve of 0.967 was obtained in the training group. Moreover, decision curve analysis also revealed that the prediction model had good clinical applicability.

Conclusions

The prediction model was efficient in predicting the risk of AKI by incorporating ultrasound examinations and a number of factors. Such included operation methods, age, congestive heart failure, body mass index, heart rate, white blood cell count, platelet count, hemoglobin, uric acid, and peak intensity (kidney cortex as well as kidney medulla).

RenalGuard system and conventional hydration for preventing contrast-associated acute kidney injury in patients undergoing cardiac interventional procedures: A systematic review and meta-analysis

BACKGROUND

Contrast-associated acute kidney injury (CA-AKI) can increase the mortality of patients undergoing transcatheter aortic valve replacement (TAVR) or percutaneous coronary intervention (PCI). The purpose of this paper was to compare the efficacy of the RenalGuard System and conventional hydration regimen in preventing CA-AKI in patients with TAVR or PCI.

METHODS

We searched PubMed, Embase, Web of Science, and the Cochrane Central Register of Clinical Trials (last updated July 11, 2020) for suitable reports. The primary outcome was the occurrence of CA-AKI. The secondary outcomes were renal replacement therapy (RRT), major cardiovascular events (MACEs), and other adverse complications.

RESULTS

The search strategy yielded 270 studies (with data for 2067 participants). In the subgroup of PCI, low incidence of CA-AKI (6.7% vs 15.7%; 95%CI: 0.27 to 0.54; I² = 8%; P < 0.00001) associate with RenalGuard group (RG) rather than control group (CG). Similarly, in the subgroup of TAVR, a low incidence of CA-AKI (15.6% vs 26.9%; 95%CI: 0.35 to 0.82; I² = 88%; P = 0.004) relates to RG. However, this result is highly heterogeneous. Compare with conventional hydration, RenalGuard significantly reduce the incidence of pulmonary edema (1.5%vs4.1%; 95%CI: 0.18 to 0.72; I² = 0%; P = 0.004).

CONCLUSIONS

RenalGuard System can lessen the risk of CA-AKI and RRT in patients undergoing PCI. But for patients experiencing TAVR, due to unique hemodynamic effects, the role of RenalGuard remains questionable. RenalGuard is more secure than conventional hydration. Future work should elucidate the feasibility and safety of this prophylactic intervention in cardiac interventional therapy.

Predictors of Acute Kidney Injury Following Surgical Valve Replacement

BACKGROUND

 Acute kidney injury is a serious complication after surgical valve replacement and holds increased mortality rates.

OBJECTIVES

 To study predictors of acute kidney injury after surgical valve replacement.

MATERIALS AND METHODS

 Patients who underwent valve surgery procedures at our center were included. Procedures included aortic valve replacement (AVR), mitral valve replacement (MVR), AVR with coronary artery bypass grafting (CABG), MVR with CABG, or AVR and MVR with/without CABG.

RESULTS

 A total of 346 patients were included. The mean age was 51.56 (16.1). Males (n = 178) comprised 51%.At the univariate level analysis, predictors of acute kidney injury were found including age, ejection fraction, hypertension, history of CAD, emergency surgery, recent myocardial infarction, diabetes, atrial fibrillation, history of heart failure, mitral regurgitation (MR), pump time >120 minutes, aortic cross clamp >90 minutes, perioperative blood transfusion, re-exploration for bleeding, use of mechanical and biologic valve in aortic position, use of biologic valve in mitral position, prolonged inotropic support, postoperative stroke, and use of angiotensin converting enzyme inhibitors (ACEi) < a month, (all p < 0.05).By Logistic regression analysis, Age (p < 0.0001, odds ratio[AOR] = 1.076), hypertension (p = 0.039, AOR = 1.829), heart failure (p = 0.019, AOR = 2.448), MR (p = 0.0001, AOR = 3.110), use of ACEi <month (p = 0.043, AOR= 2.181), pump time >120 minutes (p = 0.022, AOR = 1.797), perioperative blood transfusion (p = 0.008, AOR = 2.532), and prolonged inotropic support (p = 0.012, AOR = 2.591) were significant and independent predictors of AKI.

CONCLUSION

 Independent predictors of acute kidney injury following valve surgeries include age, hypertension, heart failure, MR, use of ACEi <month, perioperative blood transfusion, and prolonged pump time or inotropic support.

Outcome of Postcardiac Surgery Acute Myocardial Infarction and Role of Emergency Percutaneous Coronary Interventions

Background. Cardiac surgery carries a well-known risk of perioperative myocardial infarction (MI), which is associated with high morbidity and both in-hospital and late mortality. The rapid haemodynamics deterioration and presence of myocardial ischemia early after cardiac surgical operations is a complex life-threatening condition where rapid diagnosis and management is of fundamental importance. Objective. To analyse the factors associated with mortality of patients with postcardiotomy MI and to study the role of emergency coronary angiography in management and outcome. Methods. We retrospectively enrolled adult patients diagnosed to have postcardiotomy MI and underwent emergency coronary angiography at our tertiary care hospital between January 2016 and August 2019. Results. Sixty-one patients from consecutive 1869 adult patients who underwent cardiac surgeries were enrolled in our study. The studied patients had a mean age of 49 ± 16.2 years with a mean BMI of 29.5 ± 6.6 and 65.6% of them were males. As compared to the survivors group, the nonsurvivors of perioperative MI had significant preoperative CKD, postoperative AKI, longer CPB time, frequent histories of previous PCI, previous cardiotomies, pre and postoperative ECMO use, higher median troponin I levels, higher peak and 24 hours median lactate levels. Regression analysis revealed that reoperation for revascularization (OR: 23; 95% CI: 8.27–217.06; P=0.034) and hyperlactataemia (OR: 3.21; 95% CI: 1.14–9.04; P=0.027) were independent factors associated with hospital mortality after perioperative MI. Hospital mortality occurred in 25.7% vs 86.7% (P<0.001), AKI occurred in 37.1% vs 93.3% (P<0.001), haemodialysis was used in 28.6% vs 80% (P=0.002), and mediastinal exploration for bleeding was performed in 31.4% vs 80% (P=0.006) in the PCI and reoperation groups, respectively, while there were no significant differences regarding gastrointestinal bleeding, cerebral strokes, or intracerebral bleeding. The median peak troponin level was 795 (IQR 630–1200) vs 4190 (IQR 3700–6300) (P<0.001) in the PCI and reoperation groups, respectively. Absence of significant angiographic findings occurred in 18% of patients. Conclusions. Perioperative MI is associated with significant morbidities and hospital mortality. Reoperation for revascularization and progressive hyperlactataemia are independent predictors of hospital mortality. Emergency coronary angiography is helpful in diagnosis and management of perioperative MI.

Outcome of Postcardiac Surgery Acute Myocardial Infarction and Role of Emergency Percutaneous Coronary Interventions

Background. Cardiac surgery carries a well-known risk of perioperative myocardial infarction (MI), which is associated with high morbidity and both in-hospital and late mortality. The rapid haemodynamics deterioration and presence of myocardial ischemia early after cardiac surgical operations is a complex life-threatening condition where rapid diagnosis and management is of fundamental importance. Objective. To analyse the factors associated with mortality of patients with postcardiotomy MI and to study the role of emergency coronary angiography in management and outcome. Methods. We retrospectively enrolled adult patients diagnosed to have postcardiotomy MI and underwent emergency coronary angiography at our tertiary care hospital between January 2016 and August 2019. Results. Sixty-one patients from consecutive 1869 adult patients who underwent cardiac surgeries were enrolled in our study. The studied patients had a mean age of 49 ± 16.2 years with a mean BMI of 29.5 ± 6.6 and 65.6% of them were males. As compared to the survivors group, the nonsurvivors of perioperative MI had significant preoperative CKD, postoperative AKI, longer CPB time, frequent histories of previous PCI, previous cardiotomies, pre and postoperative ECMO use, higher median troponin I levels, higher peak and 24 hours median lactate levels. Regression analysis revealed that reoperation for revascularization (OR: 23; 95% CI: 8.27–217.06; P=0.034) and hyperlactataemia (OR: 3.21; 95% CI: 1.14–9.04; P=0.027) were independent factors associated with hospital mortality after perioperative MI. Hospital mortality occurred in 25.7% vs 86.7% (P<0.001), AKI occurred in 37.1% vs 93.3% (P<0.001), haemodialysis was used in 28.6% vs 80% (P=0.002), and mediastinal exploration for bleeding was performed in 31.4% vs 80% (P=0.006) in the PCI and reoperation groups, respectively, while there were no significant differences regarding gastrointestinal bleeding, cerebral strokes, or intracerebral bleeding. The median peak troponin level was 795 (IQR 630–1200) vs 4190 (IQR 3700–6300) (P<0.001) in the PCI and reoperation groups, respectively. Absence of significant angiographic findings occurred in 18% of patients. Conclusions. Perioperative MI is associated with significant morbidities and hospital mortality. Reoperation for revascularization and progressive hyperlactataemia are independent predictors of hospital mortality. Emergency coronary angiography is helpful in diagnosis and management of perioperative MI.

Cardiovascular death and progression to end-stage renal disease after major surgery in elderly patients

BACKGROUND

Reliable estimates for risk of cardiovascular-specific mortality and progression to end-stage renal disease (ESRD) among elderly patients undergoing major surgery are not available. This study aimed to develop simple risk scores to predict these events.

METHODS

In a single-centre cohort of elderly patients undergoing major surgery requiring hospital stay longer than 24 h, progression to ESRD and long-term cardiovascular-specific mortality were modelled using multivariable subdistribution hazard models, adjusting for co-morbidity, frailty and type of surgery.

RESULTS

Before surgery, 2·9 and 11·9 per cent of 16 655 patients had ESRD and chronic kidney disease (CKD) respectively. During the hospital stay, 46·9 per cent of patients developed acute kidney injury (AKI). Patients with kidney disease had a significantly higher risk of cardiovascular-specific (CV) mortality compared with patients without kidney disease (adjusted hazard ratio (HR) for CKD without AKI 1·60, 95 per cent c.i. 1·25 to 2·01; AKI without CKD 1·70, 1·52 to 1·87; AKI with CKD 2·80, 2·50 to 3·20; ESRD 5·21, 4·32 to 6·27), as well as increased progression to ESRD (AKI without CKD 5·40, 3·44 to 8·35; CKD without AKI 8·80, 4·60 to 17·00; AKI with CKD 31·60, 19·90 to 49·90). CV Death and ESRD Risk scores were developed to predict CV mortality and progression to ESRD. Calculated CV Death and ESRD Risk scores performed well with c-statistics: 0·77 (95 per cent c.i. 0·76 to 0·78) and 0·82 (0·78 to 0·86) respectively at 1 year.

CONCLUSION

Kidney disease in elderly patients undergoing major surgery is associated with a high risk of CV mortality and progression to ESRD. Risk scores can augment the shared decision-making process of informed consent and identify patients requiring postoperative renal-protective strategies.

Influence of preoperative serum creatinine level and intraoperative volume of contrast medium on the risk of acute kidney injury after transfemoral transcatheter aortic valve implantation: a retrospective observational study

Objective

This study aimed to determine if contrast medium volume (CMV) is a risk factor for acute kidney injury (AKI) during transcatheter aortic valve implantation (TAVI) via a transfemoral approach performed without major complications. All TAVI procedures performed at our institution between March 2014 and March 2018 were retrospectively reviewed. AKI was diagnosed using the Acute Kidney Injury Network classification based on the Valve Academic Research Consortium-2 definition. Procedures performed via a transapical approach and those in which circulatory dynamics failed intraoperatively were excluded.

Results

Eighty-one (96.4%) of 100 patients scheduled for TAVI were enrolled; seven (8.6%) developed AKI and 74 (91.4%) did not. The serum creatinine (SCr) level was significantly higher (p < 0.05) and the estimated glomerular filtration rate was significantly lower in the AKI group (p < 0.05). The CMV was significantly higher in the AKI group (103 ml vs 84 ml, p < 0.05), as was the CMV × SCr/BW value (3.34 vs 1.49, p < 0.01). The area under the curve for CMV × SCr/BW was 0.9228 and the cut-off value was 2.99. The CMV, SCr, and estimated glomerular filtration rate affect the likelihood of AKI after transfemoral TAVI and a CMV × SCr/BW value > 2.99 accurately predicts AKI.

Electronic supplementary material

The online version of this article (10.1186/s13104-019-4527-2) contains supplementary material, which is available to authorized users.

Patients with Atrial Fibrillation and Chronic Kidney Disease More Often Undergo Angioplasty of Left Main Coronary Artery - a 867 Patient Study

BACKGROUND/AIMS

Several studies have implicated atrial fibrillation (AF) as a contributing factor in chronic kidney disease (CKD) and cardiovascular events. The prevalence of coronary artery disease (CAD) in patients with AF varies substantially from 17% to 46.5%. There are only few studies concerning renal function in population with AF undergoing coronary angiography. The aim of the present study was to assess which type of AF is dominant in CKD population scheduled for coronary angiography and if it can influence patients' outcome, the association between renal impairment and the type of coronary procedures in AF patients and the influence of renal function on in-hospital mortality.

METHODS

We retrospectively studied 867 patients with AF hospitalized due to coronary angiography in two year time. The cut off value of CKD was eGFR ≤ 60 ml/min./1.73m2 evaluated by CKD-EPI formula.

RESULTS

A total of 867 patients with AF (44% women; mean age 72±10 years) were included in the analysis. The mean eGFR was 44±11ml/min./1.73m2 in patients with CKD and 89±18 ml/min./1.73m2 in patients with preserved renal function. Patients with CKD and AF were older (p< 0.001), had more often diabetes (p=0.009), heart failure (p< 0.001) and anaemia (p< 0.001). Patients with CKD and AF had more often permanent type of AF (p< 0.001). In CKD patients CHA2DS2VASc score was 4.3±1.5 and HAS-BLED score was 2.0±1.2 and it was significantly higher as compared to population with preserved renal function (p< 0.001, p=0.02, respectively). The use of oral anticoagulation was less frequent in CKD group (p< 0.001) although these patients had higher CHA2DS2VASc score. Patients with AF and CKD were more often admitted due to myocardial infarction (STEMI or NSTEMI) (p=0.02, p< 0.001, respectively) and more often underwent percutaneous coronary intervention (PCI) (p=0.01). Among coronary arteries the percutaneous coronary intervention (PCI) of left main artery was done more frequently in CKD patients (p=0.01). Among CKD population in-hospital mortality was significantly higher in patients with eGFR < 30 ml/min (p< 0.001).

CONCLUSION

Patients with CKD had more often permanent type of AF. Percutaneous interventions of the left main coronary artery, the only elective procedures influencing patients' prognosis, were done more frequently in CKD patients with AF. In-hospital mortality was significantly higher in patients with severe renal impairment. Despite the higher risk of ischaemic stroke in CKD group the use of oral anticoagulation therapy was significantly less frequent and the patients were deprived of the confirmed benefits of such treatment.

Risk factors and early outcomes of acute renal injury after thoracic aortic endograft repair for type B aortic dissection

Background

Thoracic endovascular aortic repair (TEVAR) has become an emerging treatment modality for acute type B aortic dissection (TBAD) patients in recent years. The risk factors and impacts of acute kidney injury (AKI) after percutaneous TEVAR, however, have not been widely established.

Methods

We retrospectively studied the clinical records of 305 consecutive patients who admitted to our institution and had TEVAR for TBAD between December 2009 and June 2013. The patients were routinely monitored for their renal functions preoperatively until 7 days after TEVAR. The Kidney Disease Improving Global Guidelines (KDIGO) criteria were used for AKI.

Results

Of the total 305 consecutive patients, 84 (27.5%) developed AKI after TEVAR, comprising 66 (21.6%) patients in KDIGO stage 1, 6 (2.0%) patients in stage 2 and 12 (3.9%) patients in stage 3. From the logistic regression analysis, systolic blood pressure (SBP) on admission >140 mmHg (odds ratio [OR], 2.288; 95% CI, 1.319–3.969) and supra-aortic branches graft bypass hybrid surgery (OR, 3.228; 95% CI, 1.526–6.831) were independent risk factors for AKI after TEVAR. Local anesthesia tended to be a protective factor (OR, 0.563; 95% CI, 0.316–1.001). The preoperative renal function, angiotensin-converting enzyme inhibitor/angiotensin receptor blocker or statin administration, volume of contrast agent, range of TBAD and false lumen involving renal artery were not associated with post-operation AKI. The in-hospital mortality and major adverse events were markedly increased with the occurrence of AKI (7.1% vs 0.9%, P=0.006; 14.3% vs 3.2%, P<0.001, respectively).

Conclusions

TEVAR for TBAD has a high incidence of AKI, which is associated with worse in-hospital outcomes. SBP on admission and supra-aortic branches graft bypass hybrid surgery were the most significant risk factors. Renopreventive measures should be considered in high-risk patients.

Neutrophil gelatinase-associated lipocalin prior to cardiac surgery predicts acute kidney injury and mortality

OBJECTIVE

We aimed to investigate whether preoperative serum neutrophil gelatinase-associated lipocalin (sNGALpre-op) predicted postoperative acute kidney injury (AKI) during hospitalisation and 1-year cardiovascular and all-cause mortality following adult cardiac surgery.

METHODS

This study was a post hoc analysis of the Effect of Remote Ischemic Preconditioning on Clinical Outcomes in Patient Undergoing Coronary Artery Bypass Graft Surgery trial involving adult patients undergoing coronary artery bypass graft. Postoperative AKI within 72 hours was defined using the International Kidney Disease: Improving Global Outcomes classification.

RESULTS

1371 out of 1612 patients had data on sNGALpre-op. The overall 1-year cardiovascular and all-cause mortality was 5.2% (71/1371) and 7.7% (105/1371), respectively. There was an observed increase in the incidence of AKI from the first to the third tertile of sNGALpre-op (30.5%, 41.5% and 45.9%, respectively, p<0.001). There was also an increase in both cardiovascular and all-cause mortality from the first to the third tertile of sNGALpre-op, linear trend test with adjusted p=0.018 and p=0.013, respectively. The adjusted HRs for those in the second and third tertiles of sNGALpre-op compared with the first tertile were 1.60 (95% CI 0.78 to 3.25) and 2.22 (95% CI 1.13 to 4.35) for cardiovascular mortality, and 1.25 (95% CI 0.71 to 2.22) and 1.91 (95% CI 1.13 to 3.25) for all-cause mortality at 1 year.

CONCLUSION

In a cohort of high-risk adult patients undergoing cardiac surgery, there was an increase in postoperative AKI and 1-year mortality from the first to the third tertile of preoperative serum NGAL. Those in the last tertile (>220 ng/L) had an estimated twofold increase risk of cardiovascular and all-cause mortality at 1 year.

CLINICAL TRIAL REGISTRATION

NCT101247545; Post-results.

Acute Kidney Injury and In-Hospital Mortality after Coronary Artery Bypass Graft versus Percutaneous Coronary Intervention: A Nationwide Study

BACKGROUND

Post-procedural acute kidney injury (AKI) is associated with significantly increased short- and long-term mortalities, and renal loss. Few studies have compared the incidence of post-procedural AKI and in-hospital mortality between 2 major modalities of revascularization - coronary artery bypass grafting (CABG) and percutaneous coronary intervention (PCI) - and results have been inconsistent.

METHODS

We generated a propensity score-matched cohort that includes a total of 286,670 hospitalizations with multi-vessel coronary disease undergoing CABG or PCI (2004-2012) from the National Inpatient Sample database. We compared incidence of AKI, AKI requiring renal replacement therapy (RRT), in-hospital mortality, hospital stay, and charges between CABG and PCI groups.

RESULTS

The incidence of AKI after CABG was higher than PCI (8.9 vs. 4.5%, OR 2.05, 95% CI 1.99-2.12, p < 0.001). The incidence of AKI requiring RRT was also higher after CABG (1.1 vs. 0.5%, OR 2.14, 95% CI 1.96-2.34, p < 0.001). Likewise, in-hospital mortality was higher after CABG than PCI (2.0 vs. 1.4%, OR 1.44, 95% CI 1.35-1.52, p < 0.001). Among patients with pre-existing chronic kidney disease (stages I-IV), those undergoing CABG was associated with 2.0-2.3-fold higher odds of developing AKI than those undergoing PCI. The patients treated with CABG had a significantly longer hospital stay and higher hospital charges.

CONCLUSIONS

Patients undergoing CABG are associated with (1) increased risk of developing post-procedural AKI, (2) higher likelihood of receiving RRT, and (3) worse short-term survival. Long-term renal outcome remains to be studied.

Outcomes and long-term survival of coronary artery surgery: The controversial role of opium as risk marker

AIM

To study survival in isolated coronary artery bypass graft (CABG) patients and to evaluate the impact of preoperative chronic opium consumption on long-term outcome.

METHODS

Cohort of 566 isolated CABG patients as Tehran Heart Center cardiac output measurement was conducted. Daily evaluation until discharge as well as 4- and 12-mo and 6.5-year follow-up information for survival status were fulfilled for all patients. Long-term 6.5-year overall and opium-stratified survival, adjusted survival curves based on opium consumption as well as possible predictors of all-cause mortality using multiple cox regression were determined by statistical analysis.

RESULTS

Six point five-year overall survival was 91.8%; 86.6% in opium consumers and 92.7% in non-opium consumers (P = 0.035). Patients with positive history of opium consumption significantly tended to have lower ejection fraction (EF), higher creatinine level and higher prevalence of myocardial infarction. Multiple predictors of all-cause mortality included age, body mass index, EF, diabetes mellitus and cerebrovascular accident. The hazard ratio (HR) of 2.09 for the risk of mortality in opium addicted patients with a borderline P value (P = 0.052) was calculated in this model. Further adjustment with stratification based on smoking and opium addiction reduced the HR to 1.20 (P = 0.355).

CONCLUSION

Simultaneous impact of smoking as a confounding variable in most of the patients prevents from definitive judgment on the role of opium as an independent contributing factor in worse long-term survival of CABG patients in addition to advanced age, low EF, diabetes mellitus and cerebrovascular accident. Meanwhile, our findings do not confirm any cardio protective role for opium to improve outcome in coronary patients with the history of smoking. Further studies are needed to clarify pure effect of opium and warrant the aforementioned findings.

The Kidney in Critical Cardiac Disease: Proceedings From the 10th International Conference of the Pediatric Cardiac Intensive Care Society

The field of cardiac intensive care continues to advance in tandem with congenital heart surgery. The focus of intensive care unit care has now shifted to that of morbidity reduction and eventual elimination. Acute kidney injury (AKI) after cardiac surgery is associated with adverse outcomes, including prolonged intensive care and hospital stays, diminished quality of life, and increased long-term mortality. Acute kidney injury occurs frequently, complicating the care of both postoperative patients and those with heart failure. Patients who become fluid overloaded and/or require dialysis are at high risk of mortality, but even minor degrees of AKI portend a significant increase in mortality and morbidity. Clinicians continue to seek methods of early diagnosis and risk stratification of AKI to prevent its adverse sequelae. Previous conventional wisdom that survivors of AKI fully recover renal function without subsequent consequences may be flawed.

Acute Kidney Injury in Pediatric Heart Failure

Acute kidney injury (AKI) is very common in pediatric medical and surgical cardiac patients. Not only is it an independent risk factor for increased morbidity and mortality in the short run, but repeated episodes of AKI lead to chronic kidney disease (CKD) especially in the most vulnerable hosts with multiple risk factors, such as heart transplant recipients. The cardiorenal syndrome, a term coined to emphasize the bidirectional nature of simultaneous or sequential cardiac-renal dysfunction both in acute and chronic settings, has been recently described in adults but scarcely reported in children. Despite the common occurrence and clinical and financial impact, AKI in pediatric heart failure outside of cardiac surgery populations remains poorly studied and there are no large-scale pediatric specific preventive or therapeutic studies to date. This article will review pediatric aspects of the cardiorenal syndrome in terms of pathophysiology, clinical impact and treatment options.

First Post-Operative Urinary Kidney Injury Biomarkers and Association with the Duration of AKI in the TRIBE-AKI Cohort

Background

We previously demonstrated that assessment of the duration of AKI, in addition to magnitude of rise in creatinine alone, adds prognostic information for long-term survival. We evaluated whether post-operative kidney injury biomarkers in urine collected immediately after cardiac surgery associate with duration of serum creatinine elevation.

Methods

We studied 1199 adults undergoing cardiac surgery in a prospective cohort study (TRIBE-AKI) and examined the association between the levels of five urinary biomarkers individually at 0–6 hours after surgery: interleukin-18 (IL-18), neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), liver fatty acid binding protein (L-FABP) and albumin with duration of serum creatinine-based AKIN criteria for AKI (0 (no AKI), 1–2, 3–6, ≥7 days).

Results

Overall, 407 (34%) patients had at least stage 1 AKI, of whom 251 (61.7%) had duration of 1–2 days, 118 (28.9%) had duration 3–6 days, and 38 (9.3%) had duration of ≥7 days. Higher concentrations of all biomarkers (per log increase) were independently associated with a greater odds of a longer duration of AKI; odds ratios and 95% confidence intervals using ordinal logistic regression were the following: IL-18: 1.22, 1.13–1.32; KIM-1: 1.36, 1.21–1.52; albumin 1.20, 1.09–1.32; L-FABP 1.11, 1.04–1.19; NGAL 1.06, 1.00–1.14). AKI duration of 7 days or longer was associated with a 5-fold adjusted risk of mortality at 3 years.

Conclusions

There was an independent dose-response association between urinary levels of injury biomarkers immediately after cardiac surgery and longer duration of AKI. Duration of AKI was also associated with long term mortality. Future studies should explore the potential utility of these urinary kidney injury biomarkers to enrich enrollment of patients at risk for longer duration of AKI into trials of interventions to prevent or treat post-operative AKI.

Chronic kidney disease as major determinant of the renal risk related to on-pump cardiac surgery: a single-center cohort study

BACKGROUND

Cardiac surgery-associated acute kidney injury (CSA-AKI) is a common complication and is associated with the poorest outcomes. Therefore, early prediction of CSA-AKI remains a major issue. Severity scores such as the STS score could estimate the risk of AKI preoperatively. The main objective of this study was to evaluate the risk factors of on-pump CSA-AKI and to assess the performance of the STS score in order to predict CSA-AKI.

PATIENTS

We identified 252 patients with on-pump cardiac surgery, and the STS score was defined retrospectively.

RESULTS

AKI occurred in 14.6% (n = 37/252) of patients and renal replacement therapy was required in 21.6% of AKI (n = 8/37). CSA-AKI was associated with 35.1% in-hospital mortality (vs. 1.4%) and nearly doubled length of stay (14.5 vs. 8.0 d). The risk of CSA-AKI was mainly determined by preoperative morbidities such as chronic kidney disease, peripheral vascular disease, and severe congestive heart failure. Long cardio-pulmonary bypass time was also a determinant. CSA-AKI + patients exhibited higher STS renal risk (5.6% vs. 2.0%; p < 0.0001), resulting in a good discrimination between AKI + and AKI - patients (area under curve [AUC] 0.80). Interestingly, a basal renal function ≤55 ml/min/1.73m² was as good as the STS score to predict CSA-AKI (AUC 0.75; P 0.26).

CONCLUSIONS

On-pump CSA-AKI was observed in nearly 15% of cases and was associated with poorer outcomes. Interestingly, the risk of CSA-AKI could be estimated preoperatively, thanks to the basal renal function, which exhibited an equal performance to the STS score.

Acute Kidney Injury and Cardiorenal Syndromes in Pediatric Cardiac Intensive Care

OBJECTIVES

The objectives of this review are to discuss the definition, diagnosis, and pathophysiology of acute kidney injury and its impact on immediate, short-, and long-term outcomes. In addition, the spectrum of cardiorenal syndromes will be reviewed including the pathophysiology on this interaction and its impact on outcomes.

DATA SOURCE

MEDLINE and PubMed.

CONCLUSION

The field of cardiac intensive care continues to advance in tandem with congenital heart surgery. As mortality has become a rare occurrence, the focus of cardiac intensive care has shifted to that of morbidity reduction. Acute kidney injury adversely impact outcomes of patients following surgery for congenital heart disease as well as in those with heart failure (cardiorenal syndrome). Patients who become fluid overloaded and/or require dialysis are at a higher risk of mortality, but even minor degrees of acute kidney injury portend a significant increase in mortality and morbidity. Clinicians continue to seek methods of early diagnosis and risk stratification of acute kidney injury to prevent its adverse sequelae.

Predictive Value of the Mehran Score for Contrast-Induced Nephropathy after Transcatheter Aortic Valve Implantation in Patients with Aortic Stenosis

BACKGROUND/AIMS

The Mehran risk score (MS) was adopted to predict the development of contrast-induced nephropathy (CIN) and includes clinical and procedural variables. In this study, we aimed to evaluate the value of MS in the prediction of CIN development after transcatheter aortic valve implantation (TAVI).

METHODS

Ninety-three patients (47 females; mean age, 77.2 ± 7.6 years) who underwent aortic valve replacement with TAVI for severe aortic stenosis in our center between June 2013 and November 2014 were included in the study. Patients were categorized into four risk groups based on MS: low (≤5), moderate (6-10), high (11-15), and very high (≥16).

RESULTS

CIN was recorded in 24 patients after TAVI (25.8%). The amount of contrast medium was significantly higher in the CIN+ group (p = 0.029), and total mortality was higher in the CIN+ group than in the CIN- group (20.1 vs. 2.9%, respectively; p = 0.024). In univariate analysis, diabetes mellitus, coronary artery disease, ejection fraction, baseline creatinine, baseline glomerular filtration rate, contrast medium volume, and MS were found to be significant risk factors for CIN (p < 0.05 for all). The receiver operating characteristic analysis of the significant variables in multivariate regression analysis revealed that the cutoff MS to predict the development of CIN was 13.0 (area under the curve, 0.654; 95% confidence interval, 0.495-0.758; sensitivity, 62%; specificity, 68%).

CONCLUSION

MS is a predictor of CIN development after TAVI. We think that the use of MS in clinical practice may decrease renal complications after TAVI.

Urine Output During Cardiopulmonary Bypass Predicts Acute Kidney Injury After Cardiac Surgery: A Single-Center Retrospective Analysis

Urine output is closely associated with renal function and has been used as a diagnostic criterion for acute kidney injury (AKI). However, urine output during cardiopulmonary bypass (CPB) has never been identified as a predictor of postoperative AKI. Considering altered renal homeostasis during CPB, we made a comprehensible approach to CPB urine output and evaluated its predictability for AKI.Patients undergoing cardiovascular surgery with the use of CPB, between January 2009 and December 2011, were retrospectively reviewed. AKI was defined as an increase in serum creatinine ≥0.3 mg/dL in the first postoperative 48 hours. We extrapolated a possible optimal amount of urine output from the plot of probability of AKI development according to CPB urine output. After separating patients by the predicted optimal value, we performed stepwise logistic regression analyses to find potential predictors of AKI in both subgroups.A total of 696 patients were analyzed. The amount of CPB urine output had a biphasic association with the incidence of AKI using 4 mL/kg/h as a boundary value. In a multivariate logistic regression to find predictors for AKI in entire patients, CPB urine output did not show statistical significance. After separating patients into subgroups with CPB urine output below and over 4 mL/kg/h, it was identified as an independent predictor for AKI with the odds ratio of 0.43 (confidence interval 0.30-0.61) and 1.11 (confidence interval 1.02-1.20), respectively.The amount of urine output during CPB with careful analysis may serve as a simple and feasible method to predict the development of AKI after cardiac surgery at an early time point.

Prognostic Usefulness of Acute Kidney Injury After Transcatheter Aortic Valve Replacement

Acute kidney injury (AKI) after transcatheter aortic valve replacement (TAVR) has been associated with increased postoperative morbidity and mortality. Long-term outcomes after TAVR with the Edwards SAPIEN valve in patients who develop AKI postoperatively are currently not well described. We retrospectively reviewed 384 consecutive patients undergoing TAVR at 2 institutions from August 2006 to April 2012. AKI was defined and staged according to Valve Academic Research Consortium-2 criteria. The incidence, multivariate predictors, and association of AKI with 3-year mortality were evaluated. Stage 1 AKI occurred in 24.0% of patients (92 of 384), stage 2 in 5.5% (21 of 384), and stage 3 in 8.1% (31 of 384). The overall operative mortality rate was 7.6%, with a mortality of 3.0% in patients with no kidney injury, 7.6% in stage 1, 23.8% in stage 2, and 32.3% in stage 3. The incidence of new postoperative dialysis was 3.1%. Survival at 3 years for no-AKI/stage 1/stage 2/stage 3 was 59.2 ± 3.3%, 43.4 ± 5.2%, 27.8 ± 10.0%, and 25.4 ± 7.9%, respectively. Logistic regression modeling for the combination of stage 2 or 3 AKI after surgery demonstrated that the last preoperative creatinine (for each 1 mg/dl increase, odds ratio = 3.23, 95% CI 1.83 to 5.69; p <0.001) and dye load (for each 10 ml increase, odds ratio = 1.04, 95% CI 1.01 to 1.08; p = 0.006) were significant predictors for AKI. In conclusion, AKI after TAVR is associated with increased postoperative and 3-year mortality. Significant multivariate predictors are potentially modifiable before the procedure.

Advanced oxidation protein products in predicting acute kidney injury following cardiac surgery

To test the hypothesis whether serum advanced oxidation protein products (AOPP) are associated with increased acute kidney injury (AKI) after cardiopulmonary bypass (CPB) and could serve as a biomarker in this aspect, we performed a prospective cohort study. Thirty-five (22.3%) patients developed AKI, and 32 age- and gender-matched patients without AKI were selected as control. Serum AOPP 1 h after CPB were significantly higher among AKI patients compared with non-AKI patients (81.8 ± 18.6 versus 67.4 ± 12.5 μmol/L, p < 0.001), with an area under the receiver-operating characteristic (ROC) curve of 0.714. An optimal serum AOPP 1 h after CPB cutoff of 69.9 μmol/L had a sensitivity of 74%, specificity of 63% and a positive predictive value of 68% for predicting AKI. These results demonstrated that serum AOPP might be an early biomarker for AKI after CPB.

Acute kidney injury following surgical aortic valve replacement

BACKGROUND

Acute kidney injury (AKI) is a significant complication of surgical aortic valve replacement (SAVR). This study sought to describe AKI following SAVR, its risk factors, predictors and effect on long-term survival.

METHODS

We retrospectively reviewed 2169 patients who underwent isolated SAVR between 2000 and 2012. The main end-points were occurrence of AKI, postoperative complications, and short- and long-term survival rates following SAVR. Patients were divided into two groups: AKI+ (n = 181) and AKI- (n = 1945).

RESULTS

AKI occurred in 8.5% of patients, of which 3.9% (n = 7) needed dialysis. Predictors of AKI after SAVR were body mass index (BMI) and intraoperative packed red blood cells (PRBC) transfusion. AKI+ patients had a more complicated postoperative course and higher cumulative mortality (25% vs. 17%, p = 0.012) with a median follow-up of 4.1 years. AKI was not found to be an independent predictor of mortality.

CONCLUSIONS

Predictors of AKI after SAVR are increased BMI and intraoperative PRBC transfusion. AKI conferred an increase in hospital length of stay and cumulative mortality while the need for postoperative dialysis was associated with the most complicated hospital stays and the highest in-hospital and cumulative mortalities; therefore careful recognition of patients at risk of AKI is warranted for a better preoperative renal optimization. However, incidence of AKI was lower than what is reported after both on-CPB cardiac surgeries and transcatheter aortic valve replacement, moreover AKI was not found to be an independent predictor of mortality.

Cardiac surgery-associated acute kidney injury: risk factors analysis and comparison of prediction models

OBJECTIVES

Cardiac surgery-associated acute kidney injury (AKI) is a well-known factor influencing patients' long-term morbidity and mortality. Several prediction models of AKI requiring dialysis (AKI-D) have been developed. Only a few direct comparisons of these models have been done. Recently, a new, more uniform and objective definition of AKI has been proposed [Kidney Disease: Improve Global Outcomes (KDIGO)-AKI]. The performance of these prediction models has not yet been tested.

METHODS

Preoperative demographic and clinical characteristics of 1056 consecutive adult patients undergoing cardiac surgery were collected retrospectively for the period 2012-2014. Multivariable logistic regression analysis was used to determine the independent predictors of AKI-D and the KDIGO-AKI stages. Risk scores of five prediction models were calculated using corresponding subgroups of patients. The discrimination of these models was calculated by the c-statistics (area under curve, AUC) and the calibration was evaluated for the model with the highest AUC by calibration plots.

RESULTS

The incidence of AKI-D was 3.5% and for KDIGO-AKI 23% (17.3% for Stage 1, 2.1% for Stage 2 and 3.6% for Stage 3). Older age, atrial fibrillation, NYHA class III or IV heart failure, previous cardiac surgery, higher preoperative serum creatinine and endocarditis were independently associated with the development of AKI-D. For KDIGO-AKI, higher body mass index, older age, female gender, chronic obstructive pulmonary disease, previous cardiac surgery, atrial fibrillation, NYHA class III or IV heart failure, higher preoperative serum creatinine and the use of cardiopulmonary bypass were independent predictors. The model by Thakar et al. showed the best performance in the prediction of AKI-D (AUC 0.837; 95% CI = 0.810-0.862) and also in the prediction of KDIGO-AKI stage 1 and higher (AUC = 0.731; 95% CI = 0.639-0.761), KDIGO-AKI stage 2 and higher (AUC = 0.811; 95% CI = 0.783-0.838) and for KDIGO-AKI stage 3 (AUC = 0.842; 95% CI = 0.816-0.867).

CONCLUSIONS

The performance of known prediction models for AKI-D was found reasonably well in the prediction of KDIGO-AKI, with the model by Thakar having the highest predictive value in the discrimination of patients with risk for all KDIGO-AKI stages.

A Meta-Analysis of Renal Function After Adult Cardiac Surgery With Pulsatile Perfusion

The aim of this meta-analysis was to determine whether pulsatile perfusion during cardiac surgery has a lesser effect on renal dysfunction than nonpulsatile perfusion after cardiac surgery in randomized controlled trials. MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials were used to identify available articles published before April 25, 2014. Meta-analysis was conducted to determine the effects of pulsatile perfusion on postoperative renal functions, as determined by creatinine clearance (CrCl), serum creatinine (Cr), urinary neutrophil gelatinase-associated lipocalin (NGAL), and the incidences of acute renal insufficiency (ARI) and acute renal failure (ARF). Nine studies involving 674 patients that received pulsatile perfusion and 698 patients that received nonpulsatile perfusion during cardiopulmonary bypass (CPB) were considered in the meta-analysis. Stratified analysis was performed according to effective pulsatility or unclear pulsatility of the pulsatile perfusion method in the presence of heterogeneity. NGAL levels were not significantly different between the pulsatile and nonpulsatile groups. However, patients in the pulsatile group had a significantly higher CrCl and lower Cr levels when the analysis was restricted to studies on effective pulsatile flow (P < 0.00001, respectively). The incidence of ARI was significantly lower in the pulsatile group (P < 0.00001), but incidences of ARF were similar. In conclusion, the meta-analysis suggests that the use of pulsatile flow during CPB results in better postoperative renal function.

Validating a scoring tool to predict acute kidney injury (AKI) following cardiac surgery

Background

Acute kidney injury (AKI) after cardiac surgery is associated with an increased risk of mortality. Preoperative risk scores can identify patients at risk for AKI and facilitate preventive strategies. Currently, validated risk scores are used to predict AKI requiring dialysis (AKI-D); less is known about whether these tools predict less severe forms of AKI.

Objective

To evaluate the Cleveland Clinic scoring tool in predicting both AKI-D and less severe stages of AKI in patients after cardiac surgery in a Canadian tertiary care center.

Design

Retrospective case–control study.

Setting

Regina Qu’Appelle Health Region (RQHR) from 2007 to 2011.

Patients

Patients who underwent cardiac surgery and developed postoperative kidney injury (n = 2316).

Measurements

Data on risk factors for AKI and outcomes of cardiac surgery were collected from a retrospective chart review.

Methods

The primary outcome was AKI, defined as Stage 1 (increase in serum creatinine 1.5-1.9 X baseline within 5 days), Stage 2 (increase 2.0-2.9 X baseline), or Stage 3 (increase 3.0 X baseline or more OR initiation of dialysis during hospital stay). We assessed the performance of a modified version of the Cleveland Clinic tool using receiver operating curve analyses.

Results

The incidence of AKI was 6.1% (Stage 1), 2.6% (Stage 2), and 5.8% (Stage 3). The area under the curve (AUC) for the Cleveland score was 0.61 (95% CI: 0.56 to 0.65; p < 0.001) for Stage 1, 0.61 (95% CI: 0.54 to 0.68; p < 0.01) for Stage 2, and 0.78 (95% CI: 0.74 to 0.82; p < 0.001) for Stage 3. Greater level of risk on the Cleveland tool was associated with a higher risk of Stage 3 AKI.

Limitations

Lack of prospective validation.

Conclusions

The modified Cleveland Clinic tool was valid in identifying patients with severe stages of AKI but did not have strong discrimination for early AKI stages.

Electronic supplementary material

The online version of this article (doi:10.1186/s40697-015-0037-x) contains supplementary material, which is available to authorized users.

Acute kidney injury after aortic valve replacement: incidence, risk factors and outcomes

The occurrence of acute kidney injury (AKI) following aortic valve replacement (AVR) has very serious clinical implications and has therefore been the focus of several studies. The authors report the results of previous studies evaluating both transcatheter AVR (TAVR) and indirectly surgical AVR (SAVR) through looking at cardiopulmonary bypass (CPB) cardiac surgeries, and identify the incidence, predictors and outcomes of AKI following AVR. In most studies, AKI was defined using the Risk, Injury, Failure, Loss and End Stage, Valve Academic Research Consortium (modified Risk, Injury, Failure, Loss and End Stage) or Valve Academic Research Consortium-2 (Acute Kidney Injury Network) AKI classification criteria. Twelve studies including more than 90,000 patients undergoing cardiac surgery on CPB were considered as well as 26 studies with more than 6000 patients undergoing TAVR. Depending on the definition used, AKI occurred in 3.4-43% of SAVR cases with up to 2.5% requiring dialysis, and in 3.4-57% of TAVR cases. Factors identified as independent predictors of AKI were: baseline kidney failure, EUROSCORE, diabetes mellitus, hypertension, chronic obstructive pulmonary disease, anemia, peripheral vascular disease, heart failure, surgical priority, CPB time, reoperation, use of intra-aortic balloon pump, need for re-exploration, contrast agent volume, transapical access, blood transfusion, postoperative thrombocytopenia, postoperative leukocytosis as well as demographic variables such as age and female gender. The 30-day mortality rate for patients with AKI following SAVR ranged from 5.5 to 46% and was 3- to 16-times higher than in those without AKI. Similarly, patients who developed AKI after TAVR had a mortality rate of 7.8-29%, which was two- to eight-times higher than those who did not suffer from AKI. AKI confers up to a fourfold increase in 1-year mortality. Finally, hospital length of stay was significantly increased in patients with AKI in both SAVR and TAVR groups, with increases up to 3- and 2.5-times, respectively.

The importance of contrast volume/glomerular filtration rate ratio in contrast-induced nephropathy patients after transcatheter aortic valve implantation

BACKGROUND/AIM

Transcatheter aortic valve implantation (TAVI) is a method which is increasingly applied in severe aortic stenosis treatment. The development of contrast-induced nephropathy (CIN) after TAVI increases morbidity and mortality rates. Within the scope of this study, the importance of the contrast medium volume to glomerular filtration rate (CV/GFR) ratio in determining the development of CIN and the amount of CV that could be applied was evaluated.

METHODS

Seventy-two patients (aged 78.6 ± 11.6 years; 38 females) who underwent aortic valve replacement with the TAVI method between June 2013 and August 2014 were included in the study. CIN was defined as an absolute increase in serum creatinine of >0.5 mg/dl or a relative increase of >25% within 48-72 h after TAVI. CIN+ and CIN-patients were classified into two groups. The χ(2) test, t test, Mann-Whitney U test, ROC analysis, and univariate and multivariate regression analyses were applied for statistical analyses.

RESULTS

CIN was detected in 16 patients (22%) in our study. Baseline creatinine, baseline GFR, the Mehran risk score, CV, and the CV/GFR ratio were determined as the predictive factors of CIN development. A CV/GFR ratio of 3.9 was specified to predict CIN development with 71% sensitivity and 80% specificity.

CONCLUSION

After TAVI, CIN may develop due to various reasons. In patients to whom TAVI was applied, the CV/GFR ratio may be a guideline helping to prevent the development of renal pathologies. The amount of contrast medium that can be given to a patient can be calculated in terms of baseline GFR.

Early prediction of acute kidney injury biomarkers after endovascular stent graft repair of aortic aneurysm: a prospective observational study

BACKGROUND

Acute kidney injury (AKI) is a common and serious condition usually detected some time after onset by changes in serum creatinine (sCr). Although stent grafting to repair aortic aneurysms is associated with AKI caused by surgical procedures or the use of contrast agents, early biomarkers for AKI have not been adequately examined in stent graft recipients. We studied biomarkers including urinary neutrophil gelatinase-associated lipocalin (NGAL), blood NGAL, N-acetyl-β-d-glucosaminidase (NAG), microalbumin (Alb), and liver fatty acid-binding protein (L-FABP) as prospective early biomarkers for AKI in patients who had received stent graft repairs of aortic aneurysms.

METHODS

In addition to pre-surgical sampling, at 2 to 6 h and at 1, 3 to 4, and 5 days or later (until stable) after surgery, urine and serum biomarkers were sampled from 47 patients who underwent stent graft repair of aortic aneurysms.

RESULTS

Using Acute Kidney Injury Network criteria, 6 (14%) of 42 retained patients developed AKI. NGAL corrected with urine Cr (NGAL/Cr) values demonstrated the best predictive value for AKI (97% specificity, 83% sensitivity at a 65.1 μg/gCr cutoff). The area under the receiver-operator characteristic curve of NGAL/Cr value 2 h after surgery was 0.9. Although NGAL/Cr, L-FABP corrected with urine Cr (L-FABP/Cr), L-FABP, NAG, and Alb corrected by urine Cr (Alb/Cr) all reached peak values before AKI detection by sCr in AKI patients, all biomarkers reached the cutoff value before AKI detection after adaption of cutoff value.

CONCLUSIONS

After stent graft repair of aortic aneurysm, NGAL/Cr is a potentially useful early biomarker for AKI.

Renal function-based contrast dosing predicts acute kidney injury following transcatheter aortic valve implantation

OBJECTIVES

This study sought to assess whether the volume of contrast media (CM) influences the occurrence of acute kidney injury (AKI) following transcatheter aortic valve implantation (TAVI).

BACKGROUND

The volume of CM has been shown to be associated with increasing risk of AKI; however, in a high-risk elderly TAVI population, the predictive value and optimal threshold of CM dose on AKI remain uncertain.

METHODS

Data of 415 consecutive transfemoral TAVI patients (age 83.6 ± 6.8 years, logistic EuroSCORE 23.0 ± 12.2%) were analyzed. AKI was defined by Valve Academic Research Consortium criteria. Based on a previous formula, the ratio of CM to serum creatinine (SCr) and body weight (BW) (CM × SCr/BW) was calculated as defining the degree of CM use. The association between CM dose and incidence of AKI, as well as predictive factors and prognosis of AKI, were investigated.

RESULTS

AKI occurred in 63 patients (15.2%). Cumulative 1-year mortality showed significant differences between the AKI and non-AKI groups (47.9% vs. 15.7%, p < 0.001). Mean CM × SCr/BW ratio was higher in the AKI group than in the non-AKI group (4.1 ± 2.9 vs. 2.9 ± 1.6, p < 0.001). By multivariate analysis, CM × SCr/BW per 1.0 increase, ejection fraction <40%, and transfusion were associated with the occurrence of AKI (odds ratio [OR]: 1.16; 95% confidence interval [CI]: 1.03 to 1.20; p = 0.017, OR: 3.01; 95% CI: 1.49 to 5.00; p = 0.001, OR: 2.73; 95% CI: 1.54 to 6.15; p = 0.001, respectively). A threshold value of CM × SCr/BW for predicting AKI was statistically identified as 2.7.

CONCLUSIONS

Although mechanisms of AKI following TAVI are multifactorial, the present study identified a relationship between CM dose increment and high prevalence of AKI. Therapeutic efforts not to exceed the threshold value may reduce the risk of AKI.

Relation between preoperative renal dysfunction and cardiovascular events (stroke, myocardial infarction, or heart failure or death) within three months of isolated coronary artery bypass grafting

Renal dysfunction is related to long-term mortality and myocardial infarction after coronary artery bypass grafting (CABG). We aimed to investigate the association between preoperative renal dysfunction and early risk of stroke, myocardial infarction, or heart failure after CABG. From the Swedish Web-system for Enhancement and Development of Evidence-based care in Heart disease Evaluated According to Recommended Therapies registry, we included all 36,284 patients who underwent primary isolated CABG from 2000 to 2008 in Sweden. The Swedish National Inpatient Registry was used to obtain the primary end point, which was rehospitalization for stroke, myocardial infarction, or heart failure ≤90 days after CABG. Logistic regression models were used to estimate the risk for the primary outcome and the secondary outcome of death from any cause, while adjusting for confounders. During 90 days of follow-up, there were 2,462 cardiovascular events and 617 deaths. In total, 17% of patients developed acute kidney injury postoperatively. Odds ratios with 95% confidence intervals for cardiovascular events after adjustment for age, gender, atrial fibrillation, left ventricular ejection fraction, diabetes mellitus, peripheral vascular disease, and history of myocardial infarction, heart failure, or stroke was 1.24 (1.06 to 1.45) in patients with an estimated glomerular filtration rate of 15 to 45 ml/min/1.73 m(2) but became nonsignificant after acute kidney injury was introduced into the statistical model. The risk of death was significantly increased in patients with estimated glomerular filtration rate of 15 to 45 ml/min/1.73 m(2) (odds ratio 1.76, 95% confidence interval 1.38 to 2.25) even after adjustment for all confounders. Renal dysfunction was associated with all-cause mortality but not with cardiovascular events during the first 3 postoperative months after primary isolated CABG.

Incidence, dynamics, and prognostic value of acute kidney injury for death after cardiac surgery

OBJECTIVE

This study relates long-term mortality after cardiac surgery to different methods of measuring postoperative renal function, classified according to the Risk, Injury, Failure, Loss, and End-stage (RIFLE) criteria. The dynamics of acute kidney injury during hospital stay were studied by comparing renal function preoperatively, at its poorest measurement, and at discharge.

METHODS

A total of 5746 patients undergoing coronary artery bypass grafting were studied in a Cox analysis, over a median follow-up time of 6.0 years (range, 2.5-9.5 years). Renal function was determined using the highest and discharge levels of plasma creatinine by Cockroft-Gault and Modification of Diet in Renal Disease formulae. Acute kidney injury was classified according to the RIFLE criteria. Renal recovery was studied in a 2-dimensional matrix, and the impact of renal function at different time points was related to survival.

RESULTS

Although the p-creatinine classified most patients in the nonacute kidney injury and Risk class; the Cockroft-Gault and Modification of Diet in Renal Disease formulae classified more patients in Injury and Failure classes; and higher Risk, Injury, and Failure classes were associated with increased long-term mortality. The effect of renal recovery on long-term survival was only in part associated with improved outcome. In addition, the poorest renal function was a stronger predictor of mortality compared with preoperative and discharge levels.

CONCLUSIONS

Classification using RIFLE criteria seems to be useful because it detects patients with renal impairment that affects long-term survival. The Modification of Diet in Renal Disease method seems to be the most robust method when predicting outcome, and the poorest renal function was the best predictor of outcome. Renal recovery was generally associated with better outcome.

Acute kidney injury and critical cardiac disease

The field of cardiac intensive care continues to advance in tandem with congenital heart surgery. The survival of patients with critical congenital heart disease is seldom in question. Consequently, the focus has now shifted to that of morbidity reduction and eventual elimination. Acute kidney injury (AKI) after cardiac surgery is associated with adverse outcomes, including prolonged intensive care and hospital stays, diminished quality of life, and increased long-term mortality. Acute kidney injury occurs frequently, complicating 30% to 40% of adult and pediatric cardiac surgeries. Patients who require dialysis are at high risk of mortality, but even minor degrees of postoperative AKI portend a significant increase in mortality and morbidity.