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.

Cost-Effectiveness of Coronary Artery Bypass Grafting and Percutaneous Coronary Intervention in Patients With Chronic Kidney Disease and Acute Coronary Syndromes in the US Medicare Program

Background Coronary revascularization provides important long-term clinical benefits to patients with high-risk presentations of coronary artery disease, including those with chronic kidney disease. The cost-effectiveness of coronary interventions in this setting is not known. Methods and Results We developed a Markov cohort simulation model to assess the cost-effectiveness of percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG) in patients with chronic kidney disease who were hospitalized with acute myocardial infarction or unstable angina. Model inputs were primarily drawn from a sample of 14 300 patients identified using the Medicare 20% sample. Survival, quality-adjusted life-years, costs, and cost-effectiveness were projected over a 20-year time horizon. Multivariable models indicated higher 30-day mortality and end-stage renal disease with both PCI and CABG, and higher stroke with CABG, relative to medical therapy. However, the model projected long-term gains of 0.72 quality-adjusted life-years (0.97 life-years) for PCI compared with medical therapy, and 0.93 quality-adjusted life-years (1.32 life-years) for CABG compared with PCI. Incorporation of long-term costs resulted in incremental cost-effectiveness ratios of $65 326 per quality-adjusted life-year gained for PCI versus medical therapy, and $101 565 for CABG versus PCI. Results were robust to changes in input parameters but strongly influenced by the background costs of the population, and the time horizon. Conclusions For patients with chronic kidney disease and high-risk coronary artery disease presentations, PCI and CABG were both associated with markedly increased costs as well as gains in quality-adjusted life expectancy, with incremental cost-effectiveness ratios indicating intermediate value in health economic terms.

Influence of chronic kidney disease on early clinical outcomes after off-pump coronary artery bypass grafting

Background

Patients with chronic kidney disease (CKD) have a high incidence of coronary heart disease, which is the leading cause of death in these patients. Coronary artery bypass grafting (CABG) significantly increases short-term mortality and decreases long-term mortality in patients with CKD compared with percutaneous coronary intervention (PCI). The effect of CKD on the early outcomes of off-pump CABG is not well-studied. We aimed to investigate the effect of CKD on early postoperative mortality and complications following off-pump CABG.

Methods

We retrospectively analyzed preoperative baseline and surgery data for 1173 patients undergoing off-pump CABG from January 2010 to December 2017 in the Department of Cardiac Surgery, Peking University First Hospital. Outpatient follow-up was performed until 30 days postoperatively. Patients with estimated glomerular filtration rates calculated according to the Chronic Kidney Disease Epidemiology Collaboration equation of ≥60 mL/min/1.73 m² were assigned to the normal renal function group (normal group, n = 924), and those with a rate < 60 mL/min/1.73 m² were assigned to the CKD group (CKD group, n = 249).

Results

Patients in the CKD group were seriously ill with multiple complications, and postoperative 30-day mortality and complication rates were significantly higher than those in the normal group. In the logistic regression analysis, after correcting for common confounding factors, namely sex, age, and left ventricular ejection fraction, preoperative CKD was a risk factor for postoperative acute kidney injury, perioperative myocardial infarction, gastrointestinal bleeding, secondary tracheal intubation, stroke, chest wound infection, prolonged mechanical ventilation (≥ 24 h), prolonged intensive care unit stay (≥ 72 h), prolonged length of stay (≥ 14 d), dialysis requirement, and postoperative death within 30 days.

Conclusions

Patients with CKD had more preoperative complications, and their postoperative 30-day mortality and complication rates after off-pump CABG were significantly higher than those of patients with normal renal function. For CABG patients with CKD, the risk of surgery should be assessed carefully, and comprehensive measures should be taken to strengthen perioperative management, with an aim to reduce complications and mortality and improve surgical outcomes.

Acute kidney injury following coronary revascularization procedures in patients with advanced CKD

BACKGROUND

Previous studies reported that compared with percutaneous coronary interventions (PCIs), coronary artery bypass grafting (CABG) is associated with a reduced risk of mortality and repeat revascularization in patients with mild to moderate chronic kidney disease (CKD) and end-stage renal disease (ESRD). Information about outcomes associated with CABG versus PCI in patients with advanced stages of CKD is limited. We evaluated the incidence and relative risk of acute kidney injury (AKI) associated with CABG versus PCI in patients with advanced CKD.

METHODS

We examined 730 US veterans with incident ESRD who underwent a first CABG or PCI up to 5 years prior to dialysis initiation. The association of CABG versus PCI with AKI was examined in multivariable adjusted logistic regression analyses.

RESULTS

A total of 466 patients underwent CABG and 264 patients underwent PCI. The mean age was 64 ± 8 years, 99% were male, 20% were African American and 84% were diabetic. The incidence of AKI in the CABG versus PCI group was 67% versus 31%, respectively (P < 0.001). The incidence of all stages of AKI were higher after CABG compared with PCI. CABG was associated with a 4.5-fold higher crude risk of AKI {odds ratio [OR] 4.53 [95% confidence interval (CI) 3.28-6.27]; P < 0.001}, which remained significant after multivariable adjustments [OR 3.50 (95% CI 2.03-6.02); P < 0.001].

CONCLUSION

CABG was associated with a 4.5-fold higher risk of AKI compared with PCI in patients with advanced CKD. Despite other benefits of CABG over PCI, the extremely high risk of AKI associated with CABG should be considered in this vulnerable population when deciding on the optimal revascularization strategy.

Postoperative Complications Are Not Elevated in Well-Compensated ESRD Patients Undergoing Cardiac Surgery: End-Stage Renal Disease Cardiac Surgery Outcomes

BACKGROUND

Patients with end-stage renal disease (ESRD) are at high risk for cardiac disease requiring surgery, and have been shown to have increased surgical risks. There have been significant improvements in ESRD management, surgical techniques, and patient selection over the past 10 y. We evaluated rates of serious postoperative outcomes in stable, well-dialyzed patients with ESRD undergoing nonemergent cardiac surgery compared to the general cardiac surgery population.

METHODS

In this propensity-score matched study, we evaluated 1451 adult patients who underwent nonemergent cardiac surgery at the University of Colorado Hospital (UCH) between 2011 and 2016. Patients with ESRD were compared to nonESRD patients. The primary outcome was a composite endpoint, including 30-d mortality, stroke, postoperative infection, and prolonged intensive care unit (ICU) length of stay (LOS).

RESULTS

A total of 35 patients with ESRD met inclusion criteria. These select patients were younger with few comorbidities than the nonESRD population. There were no statistically significant differences in the composite outcome between ESRD and nonESRD patients in the propensity-matched analysis (OR 0.70, CI 0.29-1.72, P = 0.44). There were no significant differences or trends for in-hospital mortality, postoperative stroke, infection, ICU LOS, or hospital LOS between the patients with and without ESRD.

CONCLUSIONS

Stable ESRD patients undergoing nonemergent surgery are not at increased risk of major postoperative complications when compared to those without ESRD. Well-compensated ESRD patients should not be excluded from surgical consideration.

Comparison between three different equations for the estimation of glomerular filtration rate in predicting mortality after coronary artery bypass

Background

This study was undertaken to compare the accuracy of chronic kidney disease-epidemiology collaboration (eGFR_CKD-EPI) to modification of diet in renal disease (eGFR_MDRD) and the Cockcroft-Gault formulas of Creatinine clearance (C_CG) equations in predicting post coronary artery bypass grafting (CABG) mortality.

Methods

Data from 4408 patients who underwent isolated CABG over a 11-year period were retrieved from one institutional database. Discriminatory power was assessed using the c-index and comparison between the scores’ performance was performed with DeLong, bootstrap, and Venkatraman methods. Calibration was evaluated with calibration curves and associated statistics.

Results

The discriminatory power was higher in eGFR_CKD-EPI than eGFR_MDRD and C_CG (Area under Curve [AUC]:0.77, 0.55 and 0.52, respectively). Furthermore, eGFR_CKD-EPI performed worse in patients with an eGFR ≤29 ml/min/1.73m² (AUC: 0.53) while it was not influenced by higher eGFRs, age, and body size. In contrast, the MDRD equation was accurate only in women (calibration statistics p = 0.72), elderly patients (p = 0.53) and subjects with severe impairment of renal function (p = 0.06) whereas C_CG was not significantly biased only in patients between 40 and 59 years (p = 0.6) and with eGFR 45–59 ml/min/1.73m² (p = 0.32) or ≥ 60 ml/min/1.73m² (p = 0.48).

Conclusions

In general, CKD-EPI gives the best prediction of death after CABG with unsatisfactory accuracy and calibration only in patients with severe kidney disease. In contrast, the CG and MDRD equations were inaccurate in a clinically significant proportion of patients.

Renal Disease Is Associated With Poor Outcomes Following Isolated Coronary Artery Bypass Grafting

BACKGROUND

People with renal disease have a markedly higher risk of cardiovascular disease as well as morbidity and mortality after cardiac surgery. Little is known regarding the post-operative adverse outcomes following isolated coronary artery bypass graft (CABG) in the Australian population with renal disease.

OBJECTIVES

The aim of this study was to examine the effect of different stages of renal disease on patients' risk of post-operative mortality and complications following isolated CABG in an Australian cohort.

METHODS

Using the ANZSCTS (Australian and New Zealand Society of Cardiac and Thoracic Surgeons) registry, data from 44,968 patients who underwent isolated CABG between 2001 and 2014 were used. The effect of renal disease stages on short- and long-term outcomes were examined using multivariable logistic and Cox's regression methods respectively.

RESULTS

Three of 4 Australian patients (74.6%) who underwent isolated CABG had some degree of renal disease: 50.2% mild; 20.9% moderate; 2.1% severe; and 1.6% dialysis-dependent. Adjusted risk of 30-day mortality increased with deteriorating renal disease from mild (1.6-fold) to dialysis-dependent (4.6-fold). Worsening renal disease was also associated with higher risk of post-operative complications. Hazard ratio for long-term survival shows steady increase of mortality risk with worsening renal disease categories from 1.1-fold for mild to 3.9-fold for patients on dialysis.

CONCLUSIONS

Pre-existing renal disease is significantly associated with 30-day and long-term mortality, length of intensive care unit and hospital stay as well as several other post-operative complications.

Adverse outcomes after non urological surgeries in patients with chronic kidney disease: a propensity-score-matched study

Objective

To evaluate the complications, mortality, and medical expenditures after nonurological surgical procedures in patients with chronic kidney disease (CKD).

Methods

Using claims data of Taiwan’s National Health Insurance, we conducted a matched cohort study of 35,643 patients with CKD who underwent nonurological surgeries in 2008–2013. By using a propensity-score matching procedure, 35,643 non-CKD patients were selected for comparison. Logistic regression was used to calculate the odds ratios (ORs) and the 95% confidence intervals (CIs) of postoperative complications and in-hospital mortality associated with CKD.

Results

The results showed that patients with CKD had higher risks of postoperative septicemia (OR: 1.78, 95% CI: 1.68–1.89), pneumonia (OR: 1.60, 95% CI: 1.48–1.73), stroke (OR: 1.34, 95% CI: 1.24–1.44), and in-hospital mortality (OR: 2.17, 95% CI: 1.90–2.47) compared with non-CKD patients. Longer hospital stays and higher medical expenditures after nonurological surgical procedures were noted in CKD patients. The association between CKD and postoperative adverse events was significant in both sexes, all of the age groups, and the other subgroups. Histories of myocardial infarction, epilepsy, and ages greater than 70 years were factors that were significantly associated with postoperative adverse events.

Conclusion

Compared with non-CKD patients, surgical patients with CKD exhibited more adverse events, with risks of in-hospital mortality that were approximately 2-fold higher after nonurinary surgery. These findings suggest an urgent need to revise the protocols for postoperative care in this population.

Impact of occult renal disease on the outcomes of off-pump and on-pump coronary artery bypass grafting

Purpose

Occult renal disease (ORD) is a clinical condition in which glomerular filtration rate (GFR) is less than 60 ml/min/1.73 m², while serum creatinine is ≤ 1.3 mg/dl. The aim of the study was to compare the incidence of postoperative stage I acute kidney injury (AKI) according to Acute Kidney Injury Network (AKIN) classification in patients with ORD undergoing either off-pump or on-pump coronary artery bypass grafting.

Methods

A single center prospective randomized study was conducted from March 2011 through January 2014. A total of 120 coronary artery disease (CAD) patients with ORD undergoing coronary artery bypass grafting (CABG) were randomized to either off-pump (group1, n = 62) or on-pump (group2, n = 58) CABG in 1:1 ratio by computer-generated random number table. The GFR and serum creatinine levels were measured preoperatively and postoperatively on day 1 and day 5. The primary outcome (postoperative AKI (stage I)) and secondary outcomes (AKI (stage III) requiring renal replacement therapy (RRT) death, myocardial infarction (MI), cerebrovascular accident, atrial fibrillation (AF), and re-exploration for bleeding) at 30 days were analyzed between the groups.

Results

There is no significant difference in baseline characteristics of patients between off-pump and on-pump group. The incidence of postoperative AKI (stage I) was similar between on-pump (20.69%) and off-pump (16.13%) groups (p = 0.51). There was no significant difference in mortality (p = 0.33), postoperative MI (p = 0.34), cerebrovascular accident (p = 1.00), re-exploration (p = 0.96), and AF (p = 0.50). The number of patients of stage III AKI requiring RRT was higher in the off-pump group (3 patients, 4.8%) and none in the on-pump group (p = 0.08).

Conclusions

This study demonstrated that on-pump CABG is associated with significantly lower GFR and significantly higher serum creatinine on postoperative day 1 which return to baseline by postoperative day 5. In patients with ORD undergoing CABG, the incidence of postoperative AKI and major adverse cardiac and cerebrovascular events were similar between off-pump or on-pump CABG patients.

Preoperative Renal Insufficiency: Underreporting and Association With Readmission and Major Postoperative Morbidity in an Academic Medical Center

BACKGROUND

Making a formal diagnosis of chronic kidney disease (CKD) in the preoperative setting may be challenging because of lack of longitudinal data. We explored the predictive value of a single reduced preoperative estimated glomerular filtration rate (eGFR) value on adverse patient outcomes in the first 30 days after elective surgery. We compared the rate of major postoperative adverse events, including 30-day readmission rate, hospital length of stay, infection, acute kidney injury (AKI), and myocardial infarction across patients with declining preoperative eGFR values. We hypothesized that there is an association between decreasing preoperative eGFR values and major postoperative morbidity including readmission within 30 days of discharge and that the reasons for unplanned readmissions may be associated with poor preoperative renal function.

METHODS

This was a retrospective analysis of the electronic health record of 39 989 adult patients who underwent elective surgery between June 2011 and July 2013 at our institution. Patients with reduced eGFR (<60 mL/min/1.73 m) were identified and categorized by the stages of CKD that correlated with the preoperative eGFR value. Odds of readmission to our hospital within 30 days, as well as new diagnosis of AKI, myocardial infarction, and infection, were determined with multivariate logistic regression. The subset of patients who were readmitted within 30 days also were subdivided further into patients who had an eGFR <60 mL/min/1.73 m and those with an eGFR ≥60 mL/min/1.73 m, as well as whether the readmission was planned or unplanned.

RESULTS

Of the 4053 patients with eGFR <60 mL/min/1.73 m, 3290 (81.2%) did not carry a preoperative diagnosis of CKD. Adjusted odds ratios of being readmitted were 1.48 (99% confidence interval [CI], 1.18-1.87; P < .001) for eGFR 30 to 44 mL/min/1.73 m to 2.06 (99% CI, 1.32-3.23; P < .001) for eGFR <15 mL/min/1.73 m compared with patients with a preoperative eGFR value ≥60 mL/min/1.73 m. Patients with a lower eGFR also demonstrated increasing odds of AKI from 2.78 (99% CI, 1.86-4.17; P < .001) for eGFR 45 to 59 mL/min/1.73 m to 3.81 (99% CI, 1.68-8.16; P < .001) for eGFR <15 mL/min/1.73 m.

CONCLUSIONS

This study highlights that preoperative renal insufficiency may be underreported and appears to be significantly associated with postoperative complications. It extends the association between a single low preoperative eGFR and postoperative morbidity to a broader range of surgical populations than previously described. Our results suggest that preoperative calculation of eGFR may be a relatively low-cost, readily available tool to identify patients who are at an increased risk of readmission within 30 days of surgery and postoperative morbidity in patients presenting for elective surgery.

Coronary Artery Bypass Surgery in End-Stage Renal Disease Patients

The number of patients requiring hemodialysis is continuously increasing around the world. Hemodialysis affects patient quality of life and it is also associated with a higher risk for cardiovascular events. In addition to traditional risk factors for cardiovascular events such as hypertension, hyperlipidemia, and diabetes, hemodialysis is associated with hyperphosphatemia, chronic inflammation, vascular calcification, and anemia which accelerate atherosclerosis, vascular stiffness, and cardiac ischemia. Treatment strategy for coronary revascularization in this progressive disease remains controversial. However, a systematic treatment including medical therapy and complete revascularization through a less invasive strategy should be considered in addressing this problem. This review discusses the epidemiology, vascular pathology and current treatment options in patients with end-stage renal disease requiring coronary revascularization.

Effect of Prophylactic Dialysis on Morbidity and Mortality in Non-Dialysis-Dependent Patients after Coronary Artery Bypass Grafting: A Pilot Study

BACKGROUND/AIMS

Coronary artery bypass grafting (CABG) is associated with an increased risk of morbidity and mortality in patients with pre-existing renal dysfunction. Numerous measures have been implemented to overcome this problem; however, no improvement in outcomes has been achieved. This study was aimed at investigating the effects of prophylactic dialysis on mortality and morbidity in these patients.

METHODS

This randomized-controlled clinical trial enrolled 88 non-dialysis-dependent patients with chronic kidney disease awaiting CABG surgery. Thirty-nine randomly selected patients received dialysis 3 times prior to surgery, and 49 patients formed the control group. Kaplan-Meier analysis and Cox proportional-hazards models were used to identify factors associated with survival.

RESULTS

There was no significant difference in the development of morbidities between the groups (p = 0.413). A significant difference was evident in the average survival time (p = 0.037). Cox proportional-hazards models determined that the hazard ratio of death after surgery was 10.854-fold greater in non-dialysis patients than in patients who received dialysis (hazard ratio = 2).

CONCLUSION

Prophylactic dialysis prior to CABG decreases mortality, but does not affect morbidity, in patients with renal insufficiency.

Mortality and cost of acute and chronic kidney disease after cardiac surgery

PURPOSE OF REVIEW

Acute and chronic kidney diseases (AKI and CKD) have far-reaching implications for surgical patients in regards to postoperative outcomes and hospital cost. We review the recent literature on the effects of AKI and CKD on morbidity, mortality, and resource utilization among cardiac surgery patients.

RECENT FINDINGS

Both AKI and CKD increase the risk for short-term and long-term mortalities, morbidity, length of stay, and hospital cost among postoperative patients, with increasing disease stage correlating with worse outcomes. Even the mildest forms of AKI (RIFLE-R) and CKD (proteinuria without an observed reduction in estimated glomerular filtration rate) demonstrate worse clinical outcomes compared with patients with no AKI or CKD. Outcomes are worse even in patients who achieve full renal recovery before hospital discharge. These complications dramatically increase ICU length of stay, hospital length of stay, resource utilization, and both in-hospital and postdischarge costs, as evidenced by lower rates of discharges to home.

SUMMARY

AKI and CKD remain prevalent, morbid, and costly conditions for cardiac surgery patients. Better risk stratification, early diagnosis, and earlier interventions are needed to prevent the consequences of these diseases.

Effect of dialysis dependence and duration on post-coronary artery bypass grafting outcomes in patients with chronic kidney disease: A nationwide cohort study in Asia

BACKGROUND

Chronic kidney disease (CKD) is associated with adverse outcomes in patients who undergo coronary artery bypass grafting (CABG). However, the impact of preoperative dialysis dependence and duration in CKD patients on outcomes after CABG has limited research.

OBJECTIVES

To evaluate the effect of preoperative dialysis dependence and duration on CABG outcomes in patients with CKD.

METHODS

A total of 33,920 patients without CKD and 2573 patients with CKD, all of whom underwent isolated CABG between 1998 and 2009, were identified using the Taiwan National Health Insurance Research Database. The patients with CKD were divided into non-dialysis (N=1167), dialysis<3years (N=749), and dialysis≥3years (N=657) groups. The primary outcomes were cumulative incidence of all-cause mortality, cardiovascular (CV) death, and myocardial infarction (MI) or repeat revascularization.

RESULTS

After adjustment of all covariates, a higher all-cause mortality was associated with dialysis≥3years than with dialysis<3years (hazard ratio [HR], 1.56; 95% confidence interval [CI], 1.35-1.80; P<0.001) and with non-dialysis (HR, 1.41; 95% CI, 1.20-1.66; P<0.001) after 2years of follow-up. Similar results were observed for CV death. In addition, both the dialysis groups had a higher risk of MI or revascularization than the non-dialysis group. Furthermore, subgroup analysis revealed that longer duration was associated with a higher risk of 30-day mortality (P for linear trend <0.001).

CONCLUSIONS

Among the CABG recipients, dialysis dependence is associated with a higher incidence of MI or repeat revascularization, and longer dialysis duration is associated with a higher risk of mortality.

Evaluation of influence of chronic kidney disease and sodium disturbances on clinical course of acute and sub-acute stage first-ever ischemic stroke

BACKGROUND

Chronic kidney disease (CKD) is an independent risk factor for cardiovascular morbidity and mortality. Hyponatremia is the most common electrolyte disturbance encountered in the neurological and neurosurgical intensive care units, and can exacerbate existing neurological deficits. The objective of this study was to observe the influences of chronic kidney disease and sodium disturbances on the clinical course of acute and sub-acute stages of first-ever ischemic stroke.

MATERIAL AND METHODS

464 patients with previously diagnosed chronic kidney disease (aged 70.42±11.49 years; 250 women) who had experienced their first-ever ischemic stroke were qualified. The following examinations were performed: serum levels of sodium, creatinine, lipids, estimated glomerular filtration rate (eGFR), neurological state on 1st day of stroke (according to National Institutes of Health Stroke Scale), functional state measured with the Rankin scale, (RS) and mortality rate at 1 month after stroke.

RESULTS

The neurological state on 1st day of stroke was worse and the median RS (30 days after stroke) was higher in patients with eGFR ≤60 ml/ (min×1.73). Men with eGFR ≤60 ml had greater neurological deficits and increased mortality within 1 month. In patients with eGFR >60 ml/, male sex was more often associated with worse outcomes at 1 month after ischemic stroke. Hyponatremia was associated with a more severe state in both the acute and sub-acute stages of stroke, with higher incidence of death within 1 month after stroke. Men with hyponatremia had greater neurological deficits on the 1st day and increased mortality within 1 month.

CONCLUSIONS

Renal impairment and hyponatremia are associated with worse neurological outcomes in patients in the acute stage of their first-ever stroke and within 1 month after the event. Males with impaired kidney function and hyponatremia have a more severe course in their first-ever ischemic stroke, as well as having increased mortality.

Impact of renal function in patients with multi-vessel coronary disease on long-term mortality following coronary artery bypass grafting compared with percutaneous coronary intervention

BACKGROUND

Comorbidities, such as diabetes, affect revascularization strategy for coronary disease. We sought to determine if the degree of renal impairment affected long-term mortality after percutaneous coronary intervention (PCI) compared to coronary artery bypass grafting (CABG) in patients with multi-vessel coronary disease (MVD).

METHODS AND RESULTS

8970 patients with MVD undergoing revascularization between 2004 and 2008, in two multi-center parallel PCI and CABG Australian registries were assigned to three groups based on their estimated glomerular filtration rate (eGFR)≥60 mL/min/1.73 m2 (n=1678:839), 30-59 mL/min/1.73 m2 (n=452:226) and <30 mL/min/1.73 m2 (n=74:37). We used 2:1 propensity matching to compare 3306 patients undergoing primary CABG versus PCI. Shock, myocardial infarction (MI)<24 h, previous CABG, valve surgery or PCI were exclusions. Long-term mortality (mean 3.1 years) was compared with Cox-proportional hazard-adjusted modeling. Observed long-term mortality rates (CABG vs. PCI) were 4.5% vs. 4.3% p=0.84, 12.8% vs. 17.3% p=0.12, and 23.0% vs. 40.5% p=0.05 in the three strata, respectively. In patients with eGFR≥60 mL/min/1.73 m2, long-term mortality between PCI and CABG (HR 0.99, 95% CI 0.65-1.49, p=0.95) was similar. However, amongst patients with eGFR 30-59 mL/min/1.73 m2, there was a significant mortality hazard with PCI (HR 2.00, 95% CI 1.32-3.04, p=0.001). In patients with eGFR<30 mL/min/1.73 m2, there was a trend for hazard with PCI (HR 1.66, 95% CI 0.80-3.46, p=0.17).

CONCLUSION

Long-term mortality in MVD patients with preserved renal function was very low and similar between PCI and CABG. However there was a long-term mortality hazard associated with PCI amongst patients with moderate renal impairment.

Incidence of postoperative acute kidney injury in patients with chronic kidney disease undergoing minimally invasive valve surgery

BACKGROUND

We hypothesize that minimally invasive valve surgery in patients with chronic kidney disease (CKD) is superior to a conventional median sternotomy.

METHODS

We retrospectively analyzed 1945 consecutive patients who underwent isolated valve surgery. Included were patients with CKD stages 2 to 5. In-hospital mortality, composite complication rates, and intensive care unit and total hospital lengths of stay of those who underwent a minimally invasive approach were compared with those who underwent a standard median sternotomy. Resource use was approximated based on intensive care unit and total hospital lengths of stay.

RESULTS

There were 688 patients identified; 510 (74%) underwent minimally invasive surgery, and 178 (26%) underwent a median sternotomy. There was no significant difference in mortality. Minimally invasive surgery was associated with fewer composite complications (33.1% vs 49.4%; odds ratio, 0.5; P ≤ .001), shorter intensive care unit (48 [interquartile range {IQR}, 33-74] hours vs 71 [IQR, 42-96] hours; P < .01), and hospital (8 [IQR, 6-9] days vs 10 [IQR, 8-15] days; P < .001) lengths of stay, and a lower incidence of acute kidney injury (8% vs 14.7%; odds ratio, 0.5; P = .01), compared with median sternotomy. In a multivariable analysis, minimally invasive surgery was associated with a 60% reduction in the risk of development of postoperative acute kidney injury.

CONCLUSIONS

In patients with CKD undergoing isolated valve surgery, minimally invasive valve surgery is associated with reduced postoperative complications and lower resource use.

Impact of occult renal impairment on early and late outcomes following coronary artery bypass grafting

OBJECTIVES

High serum creatinine is considered an independent risk factor for poor outcomes following coronary artery bypass grafting (CABG). However, the impact of occult renal impairment (ORI), defined as an impaired glomerular filtration rate (GFR) with a normal serum creatinine (SCr) level, remains unclear. Thus, we sought to investigate the impact of ORI on outcomes after CABG.

METHODS

Among patients undergoing their first percutaneous coronary intervention (PCI) or CABG enrolled in the CREDO-Kyoto Registry (a registry of first-time PCI and CABG patients in Japan), 1842 patients with normal SCr levels undergoing CABG were enrolled in the study. Patients were divided into two groups based on preoperative estimated GFR calculated by the Cockcroft-Gault equation: 1339 patients with estimated GFR of ≥ 60 ml/min/1.73 m(2) (normal group) and 503 with estimated GFR of <60 ml/min/1.73 m(2) (ORI group).

RESULTS

Preoperative estimated GFR differed between the groups (51.3 ± 6.6 vs 85.8 ± 23.0 ml/min/1.73 m(2), P < 0.01). ORI was associated with high in-hospital mortality (3.2 vs 1.0%, P < 0.01) and need for dialysis (2.0 vs 0.2%, P < 0.01). In terms of long-term outcomes, ORI was associated with high mortality compared with the normal (hazard ratio [95% confidence interval]: 1.72 [1.16-2.54], P < 0.01) and high incidence of composite cardiovascular events (death, stroke or myocardial infarction: 1.53 [1.16-2.02], P < 0.01).

CONCLUSIONS

ORI was an independent risk factor for early and late death as well as cardiovascular events in patients undergoing CABG with normal SCr levels. A more accurate evaluation of renal function through a combination of SCr and estimated GFR is needed in patients with normal SCr levels.

Effect of statin use on acute kidney injury risk following coronary artery bypass grafting

Acute kidney injury (AKI) is a serious complication of cardiovascular surgery. Although some nonexperimental studies suggest that statin use may reduce postsurgical AKI, methodologic differences in study designs leave uncertainty regarding the reality or magnitude of the effect. The aim of this study was to estimate the effect of preoperative statin initiation on AKI after coronary artery bypass grafting (CABG) using an epidemiologic approach more closely simulating a randomized controlled trial in a large CABG patient population. Health care claims from large, employer-based and Medicare insurance databases for 2000 to 2010 were used. To minimize healthy user bias, patients were identified who underwent nonemergent CABG who either newly initiated a statin <20 days before surgery or were unexposed for ≥200 days before CABG. AKI was identified <15 days after CABG. Multivariate-adjusted risk ratios (RRs) and 95% confidence intervals (CIs) were calculated using Poisson regression. Analyses were repeated using propensity score methods adjusted for clinical and health care utilization variables. A total of 17,077 CABG patients were identified. Post-CABG AKI developed in 3.4% of statin initiators and 6.2% of noninitiators. After adjustment, a protective effect of statin initiation on AKI was observed (RR 0.78, 95% CI 0.63 to 0.96). This effect differed by age, with an RR of 0.91 (95% CI 0.68 to 1.20) for patients aged ≥65 years and an RR of 0.62 (95% CI 0.45 to 0.86) for those aged <65 years, although AKI was more common in the older group (7.7% vs 4.0%). In conclusion, statin initiation immediately before CABG may modestly reduce the risk for postoperative AKI, particularly in younger CABG patients.

Long-term survival of patients with pulmonary disease undergoing coronary artery bypass surgery

OBJECTIVES

We sought to investigate the long-term survival of patients with obstructive, restrictive and chronic obstructive pulmonary disease (COPD) as defined by the Global Initiative for Chronic Obstructive Lung Disease (GOLD).

METHODS

A prospective database was retrospectively analysed and cross-correlated with the UK strategic tracking service to evaluate survival after primary coronary artery bypass grafts (CABG). Univariate and multivariate Cox regression analyses were performed. Three separate multivariate analyses were performed: COPD GOLD criteria for obstructive and/or restrictive lung disease, forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC) and the FEV1/FVC ratio to investigate the effect of FEV1 and FVC individually.

RESULTS

We analysed 13 337 primary CABG procedures. The median follow-up was 7 years. Univariate analysis demonstrated that obstructive (P < 0.0001), restrictive (P < 0.0001) and mixed obstructive and restrictive pulmonary disease (P < 0.0001), and COPD as defined by the GOLD criteria (P < 0.0001), are all significant factors determining long-term survival. Cox regression analysis identified age, diabetes, moderate LV, poor LV, peripheral vascular disease, dialysis, left internal mammary artery (LIMA) usage, EuroSCORE, cardiopulmonary bypass and creatinine kinase muscle-brain isoenzyme as significant factors in addition to pulmonary disease that determine long-term survival. Moderate and severe COPD defined by GOLD criteria were significant factors determining long-term survival, but mild COPD had no significant effect. Obstructive and restrictive lung disease were both significant factors determining long-term survival. Restrictive lung disease, however, carried a greater prognostic significance (higher hazard ratio 2.2 vs 1.6) than obstructive. LIMA utilization in patients with COPD was not associated with an increased intensive care unit stay, re-intubation rate or in-hospital mortality rate.

CONCLUSIONS

Pulmonary disease is a significant factor determining long-term survival. Patients with severe COPD still have a relatively good long-term survival and should not be denied surgery. LIMA utilization in patients with COPD results in a significantly increased long-term survival, without an increased intensive care unit stay, re-intubation rate or in-hospital mortality rate.

Advanced oxidation protein products as prognostic biomarkers for recovery from acute kidney injury after coronary artery bypass grafting

Recovery from acute kidney injury (AKI) is related to long-term prognosis. This study, involving 56 patients with AKI and 56 controls from a prospective cohort undergoing coronary artery bypass grafting (CABG), investigated the prognostic performance of serum levels of advanced oxidation protein products (AOPPs) for predicting non-recovered AKI and non-completely recovered AKI. AOPP levels increased significantly 7 days after surgery in patients with non-recovered or non-completely recovered AKI. Increased AOPP levels were associated with both types of poor recovery from AKI. Results from receiver-operating characteristic (ROC) curves demonstrated that AOPP levels had good prognostic value for predicting non-recovered and non-completely recovered AKI.

The impact of renal function on outcomes of bariatric surgery

The effect of CKD on the risks of bariatric surgery is not well understood. Using the American College of Surgeons National Surgical Quality Improvement Program Participant Use File, we analyzed 27,736 patients who underwent bariatric surgery from 2006 through 2008. Before surgery, 34 (0.12%) patients were undergoing long-term dialysis. Among those not undergoing dialysis, 20,806 patients (75.0%) had a normal estimated GFR or stage 1 CKD, 5011 (18.07%) had stage 2 CKD, 1734 (6.25%) had stage 3 CKD, 94 (0.34%) had stage 4 CKD, and 91 (0.33%) had stage 5 CKD. In an unadjusted analysis, CKD stage was directly associated with complication rate, ranging from 4.6% for those with stage 1 CKD or normal estimated GFR to 9.9% for those with stage 5 CKD (test for trend, P<0.001). Multivariable logistic regression demonstrated that CKD stage predicts higher complication rates (odds ratio for each higher CKD stage, 1.30) after adjustment for diabetes and hypertension. Although patients with higher CKD stage had higher complication rates, the absolute incidence of complications remained <10%. In conclusion, these data demonstrate higher risks of bariatric surgery among patients with worse renal function, but whether the potential benefits outweigh the risks in this population requires further study.