Cardiac Surgery-associated Acute Kidney Injury in Patients with Preserved Baseline Renal Function

INTRODUCTION

Cardiac surgery-associated acute kidney injury (CSA-AKI) is a powerful predictor of perioperative outcomes. We evaluated the burden of CSA-AKI in patients with preserved baseline renal function.

METHODS

The data of 2,162 adult patients who underwent cardiac surgery from January 2005 to December 2020 were analyzed. Logistic regression models were used to determine predictors of CSA-AKI and their associations with hospital mortality up to 30 days.

RESULTS

The prevalence of acute kidney injury was 43.0%, and 2.0% of patients required renal replacement therapy. Hospital mortality rate was 5.6% (non-acute kidney injury = 2.0% vs. CSA-AKI = 10.4%, P<0.001), and any degree of CSA-AKI was associated with a significant increase in death rates (stage 1 = 4.3%, stage 2 = 23.9%, stage 3 = 59.7%). Multivariable logistic regression analysis identified age, obesity, left ventricular dysfunction, previous cardiac surgery, and cardiopulmonary bypass duration as predictors of CSA-AKI. Moreover, CSA-AKI was confirmed as independent predictor of hospital mortality for stage 1 (odds ratio, 2.02; 95% confidence interval, 1.16 to 3.51; P=0.013), stage 2 (odds ratio, 9.18; 95% confidence interval, 4.54 to 18.58; P<0.001), and stage 3 (odds ratio, 37.72; 95% confidence interval, 18.87 to 75.40; P<0.001) patients.

CONCLUSION

Age, obesity, left ventricular dysfunction, previous cardiac surgery, and cardiopulmonary bypass duration are independent predictors of CSA-AKI in patients with preserved baseline renal function. The development of CSA-AKI is significantly associated with worse outcomes, and there is a dose-response relationship between acute kidney injury stages and hospital mortality.

Heart, kidney and left ventricular assist device: a complex trio

BACKGROUND

Heart failure (HF) is a complex syndrome affecting the whole body, kidneys included. The left ventricular assist device (LVAD) is a valid option for patients with very severe HF. Focusing on renal function, LVAD implantation could theoretically reverse the detrimental effects of HF syndrome on kidneys. However, implanting an LVAD is a high-risk surgical procedure, and LVAD patients have higher risk of bleeding, device thrombosis, strokes, renal impairment, multi-organ failure and infections. Furthermore, an LVAD has its own particular effects on the renal system.

METHODS

In this review, we provide a comprehensive overview of the complex interaction between LVAD and the kidneys from the pathophysiological and clinical perspectives. An analysis of the different effects of pulsatile-flow and continuous-flow LVAD is provided.

RESULTS

Despite their limitations, creatinine-based estimated glomerular filtration rate (eGFR) formulas help to stratify patients by their post-LVAD placement prognosis. Poor basal renal function, the onset of acute kidney injury or the need for renal replacement therapy after LVAD implantation negatively influences a patient's prognosis. LVAD can also prompt an improvement in renal function, however, with some counterintuitive effects on a patient's prognosis.

CONCLUSION

It is still hard to say whether different trends in eGFR depend on different renal conditions before LVAD placement, on a patient's better overall status or on a particular patient management strategy before and/or after the device's implantation. Steps should be taken to solve this question because finding the best candidates for LVAD implantation is of paramount importance to ensure the best outcomes.

Significance of pre and post-implant MELD-XI score on survival in children undergoing VAD implantation

BACKGROUND

Derangements in liver and renal function often accompany end-stage heart failure. We sought to assess the utility of an objective risk assessment tool, the Model for End-stage Liver Disease eXcluding INR (MELD-XI), to identify pediatric patients at increased risk for adverse outcomes post-ventricular assist device (VAD) implantation.

METHODS

The Pedimacs database was queried for all pediatric patients who underwent VAD implantation from September 19, 2012 to December 31, 2019. Pre-implant and early (1-week) post-implant MELD-XI scores were used to stratify patients into low, intermediate and high score cohorts. Comparison of pre-implant characteristics and post-implant outcomes were conducted across groups. Multiphase parametric hazard modeling was utilized to identify independent predictors of post-implant mortality.

RESULTS

A total of 742 patients had a calculable MELD-XI score pre-implant. When stratified by MELD-XI scores pre-implant, patients in the high MELD-XI score cohort (score >13.6) had inferior survival and increased bleeding, renal dysfunction and respiratory failure post-implant compared to intermediate and low score cohorts. Risk factors for mortality post-VAD implantation were: increasing MELD-XI scores (HR 1.1 per 1 unit rise), Pedimacs profile 1 (HR 1.6), congenital heart disease (HR 2.3) and being on a percutaneous VAD (HR 2.7). Importantly, MELD-XI score was a better predictor of post-VAD implant mortality than bilirubin or creatinine alone, neither of which were significant in the final model. Patients with increasing or continued high MELD-XI scores early post-implant had the worst survival.

CONCLUSION

The MELD-XI is an easily calculated score that serves as a promising risk assessment tool in identifying children at risk for poor outcomes post VAD implantation.

Impact of postoperative complications after cardiac surgery on long-term survival

PURPOSE

The impact of postoperative complications on long-term survival is not well characterized. We sought to study the prevalence of postoperative complications after cardiac surgery and their impact on long-term survival.

METHODS

Operative survivors (n = 26,221) who underwent coronary artery bypass grafting (CABG) (n = 13,054, 49.8%), valve surgery (n = 8667, 33.1%) or combined CABG and valve surgery (n = 4500, 17.2%) from 1993 to 2019 were included in the study. Records were reviewed for postoperative complications and long-term survival. Propensity-match analysis was performed between patients who did and did not have a postoperative complication. The associations between postoperative complications and survival were assessed using a Cox-proportional model.

RESULTS

Complications occurred in 17,463 (66.6%) of 26,221 operative survivors. A total of 17 postoperative complications were analyzed. Postoperative blood product use was the commonest (n = 12,397, 47.3%), followed by atrial fibrillation (n = 8399, 32.0%), prolonged ventilation (n = 2336, 8.9%), renal failure (n = 870, 3.3%), reoperation for bleeding (n = 859, 3.3%) and pacemaker/ICD insertion (n = 795, 3.0%). Stroke (hazard ratio [HR]: 1.55; 95% confidence interval [CI]: 1.36-1.77), renal failure (HR: 1.45; 95% CI: 1.33-1.58) and pneumonia (HR: 1.23; 95% CI: 1.11-1.36) had the strongest impact on long-term survival. Long-term survival decreased as the number of postoperative complications increased.

CONCLUSIONS

Postoperative complications after cardiac surgery significantly impact outcomes that extend beyond the postoperative period. Stroke, renal failure, and pneumonia are particularly associated with poor long-term survival.

Minimally invasive mitral valve surgery: a systematic safety analysis

Objective

Minimally invasive surgery is increasingly adopted as an alternative to conventional sternotomy for mitral valve pathology in many centres worldwide. A systematic safety analysis based on a comprehensive list of pre-specified 30-day complications defined by the Mitral Valve Academic Consortium (MVARC) criteria is lacking. The aim of the current study was to systematically analyse the safety of minimally invasive mitral valve surgery in our centre based on the MVARC definitions.

Methods

All consecutive patients undergoing minimally invasive mitral valve surgery through right mini-thoracotomy in our institution within 10 years were studied retrospectively. The primary outcome was a composite of 30-day major complications based on MVARC definitions.

Results

745 patients underwent minimally invasive mitral valve surgery (507 repair, 238 replacement), with a mean age of 62.9±12.3 years. The repair was successful in 95.8%. Overall 30-day mortality was 1.2% and stroke rate 0.3%. Freedom from any 30-day major complications was 87.2%, and independent predictors were left ventricular ejection fraction <50% (OR 1.78; 95% CI 1.02 to 3.02) and estimated glomerular filtration rate <60 mL/min/1.73 m² (OR 1.98; 95% CI 1.17 to 3.26).

Conclusions

Minimally invasive mitral valve surgery is a safe technique and is associated with low 30-day mortality and stroke rate.

Impact of vital capacity on outcome after total arch replacement

OBJECTIVES

Although chronic obstructive pulmonary disease has been recognized as a significant risk factor for open-heart surgery, the relationship between vital capacity and postoperative outcomes remains unclear. Our objective was to analyze the effect of vital capacity on outcomes after total arch replacement.

METHODS

Between January 2003 and December 2018, 228 patients undergoing total arch replacement who were elective cases with preoperative spirometry records were retrospectively reviewed. Patients were divided into two groups, based on whether their preoperative vital capacity was less than or greater than 2.5 L. We compared perioperative data and long-term outcome after adjusting their backgrounds by propensity score matching analysis.

RESULTS

The lower vital capacity group had more tracheostomy patients (5.1% vs 0.0%; p = 0.045). The actuarial survival rate was 58.0% in the lower vital capacity group and 86.3% in the higher vital capacity group at 8 years. Log-rank analysis revealed a significant difference between the two groups (p = 0.011). In the multivariate Cox proportional hazard model, vital capacity < 2.5 L (p = 0.024) and estimated glomerular filtration rate < 30mL/minute/1.73 m² (p = 0.012) showed a significant association with a higher risk of long-term mortality.

CONCLUSIONS

Vital capacity should be considered an important risk factor for postoperative respiratory complications and long-term mortality in patients undergoing total arch replacement.

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.

Non-alcoholic fatty liver disease and liver transplantation

Cirrhosis secondary to non-alcoholic steatohepatitis (NASH) is a common indication for liver transplant. In comparison to other cirrhotic patients, patients with NASH cirrhosis are more likely to be older and have the metabolic syndrome. Pre-transplant, patients require careful evaluation of cardiovascular risk. As the incidence of non-alcoholic fatty liver disease (NAFLD) is rising, a greater proportion of donor grafts have steatosis greater than 30%, which is associated with poor outcomes. Grafts with steatosis greater than 60% are unsuitable for transplant. Overall, post-transplant survival outcomes for patients with NASH cirrhosis are similar to those with cirrhosis without NASH. However, NASH cirrhosis is associated with a higher 30-day mortality, predominantly from an increase in cardiovascular events and infections. Following liver transplant, there is a significant risk of NASH recurrence, although this seldom results in allograft loss. Furthermore, a significant number of patients who had a liver transplant for other reasons develop NASH de novo. When patients with NASH cirrhosis are considered for transplant, one of the major challenges lies in identifying which patients are too high risk for surgery. This review aims to provide information to aid this decision making process, and to provide guidance on the peri-operative care strategies that can modify risk.

Risk Factors for Long-Term Mortality and Progressive Chronic Kidney Disease Associated With Acute Kidney Injury After Cardiac Surgery

The aim of the study was to evaluate risk factors for long-term mortality and progressive chronic kidney disease (CKD) after cardiac surgery in patients with normal preoperative renal function and postoperative acute kidney injury (AKI). From April 2009 to December 2012, we prospectively enrolled 3245 cardiac surgery patients of our hospital. The primary endpoints included survival rates and the secondary endpoint was the incidence of progressive chronic kidney disease (CKD) in a follow-up period of 2 years. Acute kidney injury was staged by KDIGO classification. Progressive CKD was defined as GFR ≤ 30 mL/min/1.73 m or end-stage renal disease (ESRD) (starting renal replacement therapy or renal transplantation).The AKI incidence was 39.9% (n = 1295). The 1 and 2 year overall survival (OS) rates of AKI patients were significantly lower than that for non-AKI patients (85.9% and 82.3% vs 98.1% and 93.7%, P < 0.001), even after complete recovery of renal function during 2 years after intervention (P < 0.001). The 2-year overall survival (OS) rates of patients with AKI stage 1, 2, and 3 were 89.9%, 78.6%, and 61.4% (P < 0.001), respectively. Multivariate Cox regression analysis of factors for 2-year survival rates revealed that besides age (P < 0.001), chronic cardiac failure (P < 0.001), diabetes (P < 0.001), cardiopulmonary bypass time (P < 0.01), and length of intensive care unit (ICU) stay (P = 0.004), AKI was a significant risk factor for reducing 2-year survival rates even after complete recovery of renal function (P < 0.001). The accumulated progressive CKD prevalence was significantly higher in AKI than in non-AKI patients (6.8% vs 0.2%, P < 0.001) in the 2 years after surgery. Even with complete recovery of renal function at discharge, AKI was still a risk factor for accumulated progressive CKD (RR 1.92, 95% CI 1.37-2.69).The 2-year mortality and progressive CKD incidence even after complete recovery of renal function were significantly increased in cardiac surgery patients with postoperative AKI.

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).

Three-year outcomes after percutaneous coronary intervention and coronary artery bypass grafting in patients with heart failure: from the CREDO-Kyoto percutaneous coronary intervention/coronary artery bypass graft registry cohort-2†

OBJECTIVES

Ischaemic heart disease is a major risk factor for heart failure. However, long-term benefit of percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG) in those patients has not been well elucidated.

METHODS

Of the 15 939 patients undergoing first myocardial revascularization enrolled in the CREDO-Kyoto PCI/CABG Registry Cohort-2, we identified 1064 patients with multivessel and/or left main disease with a history of heart failure (ACC/AHA Stage C or D).

RESULTS

There were 672 patients undergoing PCI and 392 CABG. Preprocedural left ventricular ejection fraction was not different between PCI and CABG (46.6 ± 15.1 vs 46.6 ± 14.6%, P = 0.89), but the CABG group included more patients with triple-vessel and left main disease (P < 0.01 each). Three-year outcomes revealed that the risk of hospital readmission for heart failure was higher after PCI than after CABG (hazard ratio [95% confidence interval]; 1.90 [1.18-3.05], P = 0.01). More importantly, adjusted mortality after PCI was significantly higher than after CABG (1.79 [1.13-2.82], P = 0.01). The risk of cardiac death after PCI was also higher than after CABG (1.98 [1.10-3.55], P = 0.02). Stratified analysis using the SYNTAX score demonstrated that risk of death was not different between PCI and CABG in patients with low (<23) and intermediate (23-32) SYNTAX scores (2.10 [0.57-7.68], P = 0.26 and 1.43 [0.63-3.21], P = 0.39, respectively), whereas those with a high (≥ 33) SYNTAX score, the risk of death was far higher after PCI than after CABG (4.83 [1.46-16.0], P = 0.01).

CONCLUSIONS

In patients with heart failure with advanced coronary artery disease, CABG was a better option than PCI because CABG was associated with better survival benefit, particularly in more complex coronary lesions stratified by the SYNTAX score.

Risk factors for postoperative mortality and morbidities in emergency surgeries

BACKGROUND

Emergency surgery itself induces high risk for postoperative mortality and morbidities; however, it remains unknown which concomitant pathological conditions of emergency surgeries are causative factors of deteriorating outcomes. This study examined the causal factors of postoperative mortality and morbidity in cases of emergency surgery.

METHODS

Patients undergoing emergency surgery from January to December 2007 were enrolled in this retrospective cohort study. Causal relationships were analyzed by stepwise multivariate logistic regression analysis between possible independent factors (sex, age, kind of surgical department, timing of surgery, duration of surgery, blood transfusion, deteriorated consciousness level, shock state, abnormal coagulate state, and history of hypertension, diabetes, ischemic heart disease, chronic obstructive pulmonary disease, renal failure, and anemia) and postoperative mortality or morbidities (failure of removal of tracheal tube after operation, tracheotomy, cerebral infarction, massive hemorrhage, severe hypotension, severe hypoxemia, and severe arrhythmia during or after surgery).

RESULTS

Shock, deteriorated consciousness level, chronic obstructive lung disease, and ischemic heart disease were significant risk factors for mortality (OR 14.2, 7.9, 6.4, and 3.8, respectively), and deteriorated consciousness level, blood transfusion, shock, chronic obstructive lung disease, diabetes, cardiovascular surgery, and operation longer than 2 h were significant risk factors for morbidity (OR 19.1, 3.3, 3.0, 2.5, 2.4, 2.4, and 1.8, respectively).

CONCLUSION

State of shock, deteriorated consciousness level, chronic obstructive lung disease, ischemic heart disease, hemorrhage requiring blood transfusion, age over 80 years, cardiovascular surgery, surgeries at night, and surgeries of duration more than 2 h cause patients to be strongly susceptible to postoperative mortality or morbidity in emergency surgeries.

Changes in renal function after implantation of continuous-flow left ventricular assist devices

OBJECTIVES

The aim of this study was to determine renal outcomes after left ventricular assist device (LVAD) implantation.

BACKGROUND

Renal dysfunction before LVAD placement is frequent, and it is unclear whether it is due to primary renal disease or to poor perfusion.

METHODS

A retrospective single-center analysis was conducted in 83 consecutive patients implanted with HeartMate II continuous-flow LVADs (Thoratec Corp., Pleasanton, California). Calculated glomerular filtration rate (GFR) was assessed on admission and 1, 3, and 6 months after implantation. To define predictors for improvement in GFR, clinical variables were examined in patients with decreased renal function (GFR <60 ml/min/1.73 m(2)) before LVAD, surviving and dialysis-free at 1 month (n = 44).

RESULTS

GFR significantly increased from admission (53.2 ± 21.4 ml/min/1.73 m(2)) to 1 month after LVAD implantation (87.4 ± 27.9 ml/min/1.73 m(2)) (p < 0.0001). Subsequently, at 3 and 6 months, GFR remained significantly (p < 0.0001) above pre-LVAD values. Of the 51 patients with GFRs <60 ml/min/1.73 m(2) before LVAD surviving at 1 month, 34 (67%) improved to GFRs >60 ml/min/1.73 m(2). Univariate pre-operative predictors for improvement in renal function at 1 month included younger age (p = 0.049), GFR improvement with optimal medical therapy (p < 0.001), intra-aortic balloon pump use (p = 0.004), kidney length above 10 cm (p = 0.023), no treatment with angiotensin-converting enzyme inhibitors or angiotensin receptor blockers (p = 0.029), higher bilirubin (p = 0.002), higher Lietz-Miller score (p = 0.019), and atrial fibrillation (p = 0.007). Multivariate analysis indicated pre-operative improved GFR (slope = 0.5 U per unit improved; 95% confidence interval: 0.2 to 0.8; p = 0.003), atrial fibrillation (slope = 27; 95% confidence interval: 8 to 46; p = 0.006), and intra-aortic balloon pump use (slope = 14; 95% confidence interval: 2 to 26; p = 0.02) as independent predictors.

CONCLUSIONS

In most patients with end-stage heart failure considered for LVAD implantation, renal dysfunction is reversible and likely related to poor renal perfusion.

Cardiothoracic ratio from postero-anterior chest radiographs: a simple, reproducible and independent marker of disease severity and outcome in adults with congenital heart disease

OBJECTIVE

The wide spectrum of intracardiac anatomy and reparative surgery available for adults with congenital heart disease (ACHD) makes uniform measurement of cardiac size and disease severity challenging. The aim of this study was to assess the prognostic potential of cardiothoracic ratio, a simple marker of cardiomegaly, in a large cohort of ACHD.

PATIENTS AND SETTING

Chest radiographs from 3033 ACHD patients attending our institution between 1998 and 2007 and 113 normal controls of similar age were analyzed blindly.

DESIGN

Cardiothoracic ratio derived from plain postero-anterior chest radiographs, was compared between ACHD patients and controls, different diagnostic subgroups and different functional classes. Relationship between cardiothoracic ratio and survival was assessed using Cox regression.

RESULTS

Average cardiothoracic ratio in ACHD was 52.0±7.6% (over 50% in 56.4%), significantly higher in all ACHD diagnostic subgroups compared to controls (42.3±4.0%, p<0.0001) and highest in the "complex" cardiac anatomy, Ebstein's anomaly and Eisenmenger subgroups. Cardiothoracic ratio related to functional class, but was high even in asymptomatic patients. During a median follow-up of 4.2years, 164 patients died. Patients with a cardiothoracic ratio >55% had an 8-fold increased risk of death compared to those in the lowest tertile (<48%). Even patients with mildly increased cardiothoracic ratio (48-55%) had an adjusted 3.6-fold increased mortality compared to the lowest tertile.

CONCLUSIONS

Cardiothoracic ratio derived from postero-anterior chest radiographs is a simple, and reproducible marker, which relates to functional class and predicts independently mortality risk in ACHD patients.

Acute kidney injury in septua- and octogenarians after cardiac surgery

Background

An increasing number of septua- and octogenarians undergo cardiac surgery. Acute kidney injury (AKI) still is a frequent complication after surgery. We examined the incidence of AKI and its impact on 30-day mortality.

Methods

A retrospective study between 01/2006 and 08/2009 with 299 octogenarians, who were matched for gender and surgical procedure to 299 septuagenarians at a university hospital. Primary endpoint was AKI after surgery as proposed by the RIFLE definition (Risk, Injury, Failure, Loss, End-stage kidney disease). Secondary endpoint was 30-day mortality. Perioperative mortality was predicted with the logistic European System for Cardiac Operative Risk Evaluation (EuroSCORE).

Results

Octogenarians significantly had a mean higher logistic EuroSCORE compared to septuagenarians (13.2% versus 8.5%; p < 0.001) and a higher proportion of patients with an estimated glomerular filtration rate (eGFR) < 60 ml × min^-1 × 1.73 m^-2. In contrast, septuagenarians showed a slightly higher median body mass index (28 kg × m^-2 versus 26 kg × m^-2) and were more frequently active smoker at time of surgery (6.4% versus 1.6%, p < 0.001). Acute kidney injury and failure developed in 21.7% of septuagenarians and in 21.4% of octogenarians, whereas more than 30% of patients were at risk for AKI (30% and 36.3%, respectively). Greater degrees of AKI were associated with a stepwise increase in risk for death, renal replacement therapy and prolonged stays at the intensive care unit and at the hospital in both age groups, but without differences between them. Overall 30-day mortality was 6% in septuagenarians and 7.7% in octogenarians (p = 0.52).

The RIFLE classification provided accurate risk assessment for 30-day mortality and fair discriminatory power.

Conclusions

The RIFLE criteria allow identifying patients with AKI after cardiac surgery. The high incidence of AKI in septua- and octogenarians after cardiac surgery should prompt the use of RIFLE criteria to identify patients at risk and should stimulate institutional measures that target AKI as a quality improvement initiative for patients at advanced age.

Impact of estimated glomerular filtration rate after valve and combined valve and coronary surgery

Preoperative renal impairment predicts postoperative mortality in patients undergoing cardiac surgery. We examined the impact of three equations for glomerular filtration rate (GFR) estimation on mortality. This is a retrospective, observational study on patients undergoing valve (n = 594) and combined valve and coronary procedures (n = 412). Glomerular filtration rate was estimated with modification in diet and renal disease (MDRD), Cockcroft-Gault (CG) equation, and Mayo-Clinic (MC) equation. Mean age was 65 ± 11 years and mean logistic EuroSCORE was 9.0 [95% confidence interval (CI): 8.4-9.7]. Preoperative kidney dysfunction (eGFR <60 ml/min/1.73 m²) is associated with increased risk for mortality. Hazard ratios for 30-day mortality differed between eGFR equations [MC 2.6 (95% CI: 1.6-4.1); MDRD 2.9 (95% CI: 1.9-4.4); CG 3.9 (95% CI: 2.2-5.2)]. Discriminatory performance of GFR equations was comparable with logistic EuroSCORE, but CG and MC discriminated significantly better than MDRD. Median intensive care unit stay did not differ, but Bland-Altman plots showed considerable variation between eGFR equations, indicating that they cannot be used interchangeably. Substantial amount of agreement was achieved with CG and MDRD. Only one equation should be used in one institution. The bias between equations varied considerably. Impaired preoperative kidney dysfunction is associated with increased risk for mortality irrespective of the formula used.

Age- and gender-specific values of estimated glomerular filtration rate among 6232 patients undergoing cardiac surgery

Impaired preoperative renal function as estimated by glomerular filtration rate (GFR) is an independent risk factor for mortality after cardiac surgery. Little is known about the actual prevalence of renal dysfunction among patients undergoing cardiac surgery in Germany. We performed a retrospective analysis of 6232 patients from 20 to 80 years. GFR was estimated with the modification of diet in renal disease (MDRD) formula. There was an age-dependent decrease in estimated glomerular filtration rates (eGFR) among both men and women. There is a stepwise age-dependent increase of chronic kidney disease (CKD) stages 3-5 (<60 ml/min/1.73 m(2)). The lower the eGFR the higher the risk for mortality [odds ratio 2.93 95%-confidence interval (CI) 1.92-4.53] for eGFR<30 ml/min/1.73 m(2); odds ratio 1.93 (95%-CI 1.56-2.39) for eGFR 30-60 ml/min/1.73 m(2) compared to patients with an eGFR>60 ml/min/1.73 m(2). The actual mortality rates varied between 6.3% (307/4869) for patients with an eGFR>60 ml/min/1.73 m(2), 11.3% (137/1051) for patients with an eGFR of 30-60 ml/min/1.73 m(2) and 16.6% (27/163) for patients with an eGFR<30 ml/min/1.73 m(2). Estimated GFR declines are age- and gender-dependent. Preoperative renal dysfunction is an important predictor of in-hospital mortality after cardiac surgery.

Acute kidney injury is associated with increased long-term mortality after cardiothoracic surgery

BACKGROUND

Long-term survival after acute kidney injury (AKI) is poorly studied. We report the relationship between long-term mortality and AKI with small changes in serum creatinine during hospitalization after various cardiothoracic surgery procedures.

METHODS AND RESULTS

This was a retrospective study of 2973 patients with no history of chronic kidney disease who were discharged from the hospital after cardiothoracic surgery between 1992 and 2002. AKI was defined by the RIFLE classification (Risk, Injury, Failure, Loss, and End stage), which requires at least a 50% increase in serum creatinine and stratifies patients into 3 grades of AKI: Risk, injury, and failure. Patient survival was determined through the National Social Security Death Index. Long-term survival was analyzed with a risk-adjusted Cox proportional hazards regression model. Survival was worse among patients with AKI and was proportional to its severity, with an adjusted hazard ratio of 1.23 (95% CI 1.06 to 1.42) for the least severe RIFLE risk class and 2.14 (95% CI 1.73 to 2.66) for the RIFLE failure class compared with patients without AKI. Survival was worse among all subgroups of cardiothoracic surgery with AKI except for valve surgery. Patients with complete renal recovery after AKI still had an increased adjusted hazard ratio for death of 1.28 (95% CI 1.11 to 1.48) compared with patients without AKI.

CONCLUSIONS

The risk of death associated with AKI after cardiothoracic surgery remains high for 10 years regardless of other risk factors, even for those patients with complete renal recovery. Improved renal protection and closer postdischarge follow-up of renal function may be warranted.

Renal function and outcome after continuous flow left ventricular assist device implantation

BACKGROUND

Renal dysfunction as a risk factor with the use of left ventricular assist devices (LVAD) is controversial. We determined the effect of renal function on outcomes after continuous flow LVAD implantation.

METHODS

Eighty-six patients with advanced heart failure undergoing continuous flow LVAD implantation as bridge to transplantation from November 1998 to July 2007 were retrospectively analyzed. Renal function was assessed using the Modification of Diet in Renal Disease study-derived glomerular filtration rates (GFR [mL x min(-1) x 1.73 m(-2)]). Patients were categorized into two groups based on pre-LVAD GFR: those with normal renal function (GFR > 60, n = 46), and those with renal dysfunction (GFR < 60, n = 40).

RESULTS

Post-LVAD survival at 1, 3, and 6 months for GFR greater than 60 was 91.3%, 79.9%, 72.6%, respectively, and for GFR less than 60, it was 92.5%, 66.5%, 47.9%, respectively (p = 0.038). Bridge-to-transplant rate was lower for GFR less than 60 than for GFR greater than 60 (40.0% versus 63.0%, p = 0.033). For GFR less than 60, GFR improved on LVAD support: implant to month 6, 41.7 +/- 11.5 to 62.7 +/- 25.0 (p = 0.021). Post-LVAD survival was improved in GFR less than 60 patients who after LVAD implantation recovered renal function to GFR greater than 60 (p < 0.001). Patients with post-LVAD renal failure had significantly lower post-LVAD survival regardless of pre-LVAD renal function (p < 0.001).

CONCLUSIONS

Patients with renal dysfunction have poorer outcomes after continuous flow LVAD implantation. However, renal function improves after LVAD implantation and is associated with improved survival. Our data underscore the importance of end-organ function in patient selection for LVAD therapy.

Impact of preoperative renal dysfunction on in-hospital mortality after solitary valve and combined valve and coronary procedures

BACKGROUND

Limited information exists on the influence of preoperative renal dysfunction on in-hospital mortality after valve and combined valve and coronary procedures. The impact of preoperative renal dysfunction on patient outcome was investigated.

METHODS

This was a retrospective observational study of 916 patients who underwent solitary valve or combined procedures. Primary outcome was in-hospital mortality. Preoperative estimated glomerular filtration rate (eGFR) was calculated with the abbreviated Modification of Diet in Renal Disease formula.

RESULTS

Independent predictors of death were prolonged stay in the intensive care unit (odds ratio [OR], 1.03; 95% confidence interval [CI], 1.01 to 1.05), preoperative atrial fibrillation (OR, 1.61; 95% CI, 1.02 to 2.54), chronic obstructive pulmonary disease (OR, 2.2; 95% CI, 1.06 to 4.55), and prolonged operation time (OR, 1.01; 95% CI, 1.00 to 1.01). Each unit of the eGFR (mL/min/1.73 m(2)) above average exerted a renoprotective effect (OR, 0.97; 95% CI, 0.96 to 0.98). The final regression model showed no lack of fit (Hosmer-Lemeshow test, p = 0.38) and a good discrimination performance in a receiver operating characteristic analysis (area under the curve, 0.84; 95% CI, 0.80 to 0.88). The lower the preoperative eGFR rate, the longer the postoperative stay at the intensive care unit.

CONCLUSIONS

Renal dysfunction is an important independent predictor of in-hospital mortality in adult patients after valve and combined valve and coronary procedures.