Extent and severity of coronary disease and mortality in patients with end-stage renal failure evaluated for renal transplantation

Predicting Contrast-induced Renal Complications

Chronic kidney disease is an independent risk factor for the development of coronary artery disease and overlaps with other risk factors such as hypertension and diabetes. Percutaneous coronary intervention is a cornerstone of therapy for coronary artery disease and requires contrast media, which can lead to renal injury. Identifying patients at risk for contrast-associated acute kidney injury (CA-AKI) is critical for preventing kidney damage, which is associated with both short- and long-term mortality. Determination of the potential risk for CA-AKI and a new need for dialysis using validated risk prediction tools identifies patients at high risk for this complication. Identification of patients at risk for renal injury after contrast exposure is the first critical step in prevention. Contrast media volume, age and sex of the patient, a history of chronic kidney disease and/or diabetes, clinical presentation, and hemodynamic and volume status are factors known to predict incident contrast-induced nephropathy. Recognition of at-risk patient subpopulations allows for targeted, efficient, and cost-effective strategies to reduce the risk of renal complications resulting from contrast media exposure.

Predicting Contrast-Induced Renal Complications

Chronic kidney disease is a major risk factor for developing coronary artery disease, serving as an independent risk factor while overlapping with other risk factors. Percutaneous coronary intervention is a cornerstone of therapy for coronary artery disease and requires contrast media, which can contribute to renal injury. Identifying patients at risk for contrast-induced nephropathy is critical for preventing renal injury, which is associated with short- and long-term mortality. Determination of the potential risk for contrast-induced nephropathy and a new need for dialysis using validated risk prediction tools is a method of identifying patients at high risk for this complication.

The assessment of coronary artery disease in patients with end-stage renal disease

Cardiovascular disease (CVD) remains the leading cause of morbidity and mortality among patients with end-stage renal disease (ESRD). Clustering of traditional atherosclerotic and non-traditional risk factors drive the excess rates of coronary and non-coronary CVD in patients with ESRD. Coronary artery disease (CAD) is a key disease process, present in ∼50% of the haemodialysis population ≥65 years of age. Patients with ESRD are more likely to be asymptomatic, posing a challenge to the correct identification of CAD, which is essential for appropriate risk stratification and management. Given the lack of randomized clinical trial evidence in this population, current practice is informed by observational data with a significant potential for bias. For this reason, the most appropriate approach to the investigation of CAD is the subject of considerable discussion, with practice patterns largely varying between different centres. Traditional imaging modalities are limited in their diagnostic accuracy and prognostic value for cardiac events and survival in patients with ESRD, demonstrated by the large number of adverse cardiac outcomes among patients with negative test results. This review focuses on the current understanding of CAD screening in the ESRD population, discussing the available evidence for the use of various imaging techniques to refine risk prediction, with an emphasis on their strengths and limitations.

Longer Inflation Duration and Predilation-Sizing-Postdilation Improve Bioresorbable Scaffold Outcomes in a Long-term All-Comers Canadian Registry

BACKGROUND

Real-world long-term safety and efficacy of the ABSORB (Abbott Vascular, Santa Clara, CA) bioresorbable vascular scaffold has not been well characterized in the literature, particularly in the setting of acute coronary syndromes (ACS). Herein, we report outcomes up to 4 years in such a high-risk cohort, with identification of parameters associated with better outcomes.

METHODS

ReABSORB is a Canadian dual-centre, prospective, nonrandomized, all-comers registry consisting of 125 consecutively enrolled nontrial patients between October 2012 and December 2016. Angiographic and clinical follow-up is now available up to 4 years.

RESULTS

Average age was 59 ± 11 years and 69% were male. Most (70.4%) presented with ACS and the median available follow-up was 1330 days (interquartile range, 1035-1483). Treated lesions (n = 163) were type A in 23%, type B (1 or 2) in 64%, and type C in 13%. Procedural success and device success were 98.2% and 98.8%, respectively. Using Kaplan-Meier methods, major adverse cardiac event-free survival (EFS) up to 4 years of clinical follow-up was 90.7% overall. However, use of a predilation-sizing-postdilation (PSP) technique was associated with an EFS rate of 95.8% vs 74.0% without PSP (P = 0.001). No significant differences in major adverse cardiac EFS rates were found between patients with or without ACS (92.7% vs 86.0%, respectively, P = 0.239). Use of PSP as well as inflation time ≥ 60 seconds were independent predictors of EFS at 2 years.

CONCLUSIONS

In this prospective, real-world registry with mostly ACS patients, use of the recommended PSP implantation technique and longer inflations times were associated with significantly higher EFS.

Risk-stratified cardiovascular screening including angiographic and procedural outcomes of percutaneous coronary interventions in renal transplant candidates

Background. Benefits of cardiac screening in kidney transplant candidates (KTC) will be dependent on the availability of effective interventions. We retrospectively evaluated characteristics and outcome of percutaneous coronary interventions (PCI) in KTC selected for revascularization by a cardiac screening approach. Methods. In 267 patients evaluated 2003 to 2006, screening tests performed were reviewed and PCI characteristics correlated with major adverse cardiovascular events (MACE) during a follow-up of 55 months. Results. Stress tests in 154 patients showed ischemia in 28 patients (89% high risk). Of 58 patients with coronary angiography, 38 had significant stenoses and 18 cardiac interventions (6.7% of all). 29 coronary lesions in 17/18 patients were treated by PCI. Angiographic success rate was 93.1%, but procedural success rate was only 86.2%. Long lesions (P = 0.029) and diffuse disease (P = 0.043) were associated with MACE. In high risk patients, cardiac screening did not improve outcome as 21.7% of patients with versus 15.5% of patients without properly performed cardiac screening had MACE (P = 0.319). Conclusion. The moderate procedural success of PCI and poor outcome in long and diffuse coronary lesions underscore the need to define appropriate revascularization strategies in KTC, which will be a prerequisite for cardiac screening to improve outcome in these high-risk patients.

A kidney transplant center's initial experiences in eastern Turkey

OBJECTIVES

Kidney transplantation is the best treatment method associated with improved quality of life and better survival for patients with end-stage renal disease. We started performing kidney transplantations in November 2010. We have performed 19 kidney transplantations so far. Fourteen of these were from living donors and five from deceased donors. Here, we present our initial experiences with 14 kidney transplant recipients from living donor kidney transplantations.

MATERIALS AND METHODS

All recipients and their donors underwent detailed clinical history and examination. Recipients and their donors were followed in the transplant clinic during hospitalization.

RESULTS

The male-to-female ratio was 11:3 in recipients. The mean age of recipients was 27.8 years (range 4-58 years). The number of the related, emotionally related, and unrelated transplantations were 9, 3, 2, respectively. The mean warm ischemic time was 95.7 seconds (range 52-168 seconds). Urine output started immediately after vascular anastomosis in all. The mean time of discharge from hospital was postoperative day 8 (range 4-18 days). The mean flow up was 125 days (range 18-210 days). Graft survival was 100% in this period, but one patient died from sepsis after 56 days. No kidney was lost from rejection, technical causes, infection, or recurrent disease.

CONCLUSION

If transplant centers are as equipped and experienced as ours, kidney transplant programs should be started immediately so that they can reduce the number of the patients in waiting list for kidney transplantation.

Coronary artery disease in a large renal transplant population: implications for management

Coronary artery disease (CAD) accounts for approximately one-half of the sizable mortality in patients with end-stage renal disease who have undergone transplantation. The study was a retrospective review of 1460 patients who underwent renal transplantation at the Mount Sinai Medical Center from January 1, 2000 to October 31, 2009. Noninvasive stress testing was performed in 848 patients (88.1%) with 278 patients (32.8%) having abnormal results. Cardiac catheterization was performed in 357 patients (37.1%) and of these, 212 patients had obstructive disease (59.4%). At 5 years posttransplant, there was no statistically significant difference between those with nonobstructive CAD and those who required percutaneous or surgical interventions (adjusted hazard ratio [aHR], 1.243; CI 95%, 0.513-3.010; p = 0.630). Those with medically managed obstructive CAD had significantly higher rates of death at the 5-year period when compared to those who received percutaneous intervention (aHR, 3.792; CI 95%, 1.320-10.895; p = 0.013) or those who received coronary artery bypass grafting (aHR, 6.691; CI 95%, 1.200-37.323). Because noninvasive imaging is poorly predictive of coronary disease in this high-risk population, an anatomic diagnosis is recommended. Revascularization may result in improved long-term outcomes.

Issues regarding 'immortal time' in the analysis of the treatment effects in observational studies

In observational studies, treatment is often time dependent. Mishandling the time from the beginning of follow-up to treatment initiation can result in bias known as immortal time bias. Nephrology researchers who conduct observational research must be aware of how immortal time bias can be introduced into analyses. We review immortal time bias issues in time-to-event analyses in the biomedical literature and give examples from the nephrology literature. We also use simulations to quantify the bias in different methods of mishandling immortal time; intuitively explain how bias is introduced when immortal time is mishandled; raise issues regarding unadjusted treatment comparison, patient characteristics comparison, and confounder adjustment; and, using data from DaVita Inc., linked with the Centers for Medicare & Medicaid Services end-stage renal disease database, show that the severity of bias and the issues described can occur in actual data analyses of patients with end-stage renal disease. In the simulation examples, mishandling immortal time led to an underestimated hazard ratio (treatment vs. control), thus an overestimated treatment effect, by as much as 96%, and an overestimated hazard ratio by as much as 138%, depending on the distribution of 'survival' time and the method used. Results from the DaVita data were consistent with the simulation. Careful consideration of methodology is needed in observational analyses with time-dependent treatment.

Osteoprotegerin and progression of coronary and aortic calcifications in chronic kidney disease

Vascular calcifications (VCs) are important predictors of cardiovascular mortality in patients with chronic kidney disease (CKD). We have shown previously that osteoprotegerin (OPG), a potential early biomarker for VC, was an independent predictor of mortality in CKD patients. The aim of our study was to follow longitudinally coronary and aortic VCs. VCs were measured using Siemens 16 detector CT in a group of predialysis and hemodialyzed patients before and after a follow-up of 4 years. Some of these patients were transplanted in the meantime. Renal function, calcium, phosphate, iPTH, hs-CRP (high sensitive protein C reactive), and OPG serum levels were also compared. VCs progressed in predialysis, hemodialyzed, and transplanted patients but the progression was not the same in all arterial beds. A progression of coronary calcifications was observed in predialysis and transplanted patients, while aortic calcifications worsened significantly only in hemodialyzed patients. OPG serum levels and hs-CRP were significantly lower among transplanted patients. We concluded that VC depends on the severity of the kidney disease. Transplanted patients are not protected from VC, yet their OPG serum levels were significantly lower, suggesting that there is no link between between OPG levels and severity of VC. Longer follow-up of these patients would be necessary to assess whether a decline in OPG correlates with better survival.

Preemptive deceased donor kidney transplant not associated with patient survival benefit in minority kidney transplant recipients

Previous studies have shown an inverse association between pre-transplant dialysis exposure and post-kidney transplant outcomes. Socioeconomic and allocation factors, in contrast to medical factors, play a greater role in dialysis exposure among minorities, and medical causes for delay may impact post-transplant outcomes. This study sought to test whether minorities behaved similarly to Caucasians with regard to the effect of duration of dialysis on post-transplant outcomes. All primary deceased donor kidney transplants between 1997 and 2004 (n = 54,162) were analyzed from the Organ Procurement and Transplant Network database and were categorized as either Caucasian or minority. Adjusted patient and graft survivals were determined in each subgroup based on the duration of pre-transplant dialysis. Caucasians recipients show a clear stepwise increase in risk of graft failure and death with increasing duration of dialysis. The risk of graft failure among minorities increased less without a clear stepwise pattern. The risk of death, however, showed a U-shaped risk profile with the highest risk of death among preemptive transplants and recipients with more than five yr of dialysis. The disparate effect of dialysis on minorities suggests that a selection bias and not a biologic effect may explain the association between dialysis duration and outcomes after kidney transplantation previously reported.

SYNTAX Score is associated with worse outcomes after off-pump coronary artery bypass grafting surgery for three-vessel or left main complex coronary disease

OBJECTIVE

The SYNergy between percutaneous intervention with TAXus drug eluting stents and cardiac surgery (SYNTAX) Score is a tool for risk stratification of patients according to the complexity of coronary lesions developed during the SYNTAX trial. We examined the influence of the SYNTAX Score on the incidence of major adverse cardiac and cerebrovascular events.

METHODS

All patients with de novo left main or 3-vessel disease undergoing coronary artery bypass grafting from January 2005 to December 2008 at our institution (Hospital Clínico San Carlos, Madrid, Spain) were retrospectively assessed, and their SYNTAX Score was calculated. The influence of the SYNTAX Score on postprocedural and follow-up mortality and combined major adverse cardiac and cerebrovascular events (including death, myocardial infarction, cerebrovascular accident, and repeat revascularization) was identified by multivariate analysis. Balancing score analysis was performed to eliminate the effect of potential confounders.

RESULTS

A total of 716 patients were enrolled. Mean SYNTAX Score was 34.5 (standard deviation, 6.7; range, 11.5-76). Three groups of patients were identified according to the score terciles: low (≤33), intermediate (33-37), and high (>37). These terciles scores differed greatly from those reported by the SYNTAX trial investigators. The multivariate analysis identified that the SYNTAX Score was associated with follow-up mortality (hazard ratio = 1.046, P = .015) and combined early and follow-up major adverse cardiac and cerebrovascular events (odds ratio = 1.079, P < .001; and hazard ratio = 1.034, P = .026, respectively). Balancing score-adjusted analyses demonstrated that the SYNTAX Score was independently associated with early and late major adverse cardiac and cerebrovascular events (odds ratio = 1.65, P < .001; and hazard ratio = 1.034, P = .027, respectively).

CONCLUSIONS

SYNTAX Score was remarkably high among patients undergoing surgical off-pump myocardial revascularization at our institution. In this subset of patients, a higher SYNTAX Score was associated with a higher incidence of in-hospital and follow-up major adverse cardiac and cerebrovascular events after coronary artery bypass grafting, but not with early or late mortality.

Coronary angiography is a better predictor of mortality than noninvasive testing in patients evaluated for renal transplantation

OBJECTIVES

The goal of this study was to compare whether coronary angiography or noninvasive imaging more accurately identifies coronary artery disease (CAD) and predicts mortality in patients with end-stage renal disease (ESRD) under evaluation for transplantation.

BACKGROUND

CAD is a leading cause of mortality in patients with ESRD. The optimal method for identifying CAD in ESRD patients evaluated for transplantation remains controversial with a paucity of prognostic data currently available comparing noninvasive methods to coronary angiography.

METHODS

The study cohort consisted of 57 patients undergoing both coronary angiography and stress perfusion imaging. Severe CAD was defined by angiography as ≥ 70% stenosis, and by noninvasive testing as ischemia in ≥ 1 zone. Follow-up for all cause mortality was 3.3 years.

RESULTS

On noninvasive imaging, 63% had ischemia. On angiography, 40% had at least one vessel with severe stenoses. Abnormal perfusion was observed in 56% of patients without severe disease angiographically. Noninvasive imaging had poor specificity (24%) and poor positive predictive value (43%) for identifying severe disease. Angiography but not noninvasive imaging predicted survival; 3 year survival was 50% and 73% for patients with and without severe CAD by angiography (p<0.05).

CONCLUSIONS

False positive scintigrams limited noninvasive imaging in patients with ESRD. Angiography was a better predictor of mortality compared with noninvasive testing.