Validation of a strategy to diagnose coronary artery disease and predict cardiac events in high-risk renal transplant candidates

Standardized risk-stratified cardiac assessment and early posttransplant cardiovascular complications in kidney transplant recipients

Introduction

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality in kidney transplant recipient (KTR). There is a dearth of standardized guidelines on optimal cardiovascular evaluation of transplant candidates.

Methods

This single-center cohort study aims to determine the effectiveness of our standardized risk-stratified pretransplant cardiovascular screening protocol, which includes coronary angiography (CAG), in identifying advanced CVD, the proper pretransplant management of which could lead to a reduction in the incidence of major cardiac events (MACE) in the early posttransplant period.

Results

Out of the total 776 KTR transplanted between 2017 and 2019, CAG was performed on 541 patients (69.7%), of whom 22.4% were found to have obstructive coronary artery disease (CAD). Asymptomatic obstructive CAD was observed in 70.2% of cases. In 73.6% of cases, CAG findings resulted in myocardial revascularization. MACE occurred in 5.6% (N = 44) of the 23 KTR with pretransplant CVD and 21 without pretransplant CVD. KTR with posttransplant MACE occurrence had significantly worse kidney graft function at the first year posttransplant (p = 0.00048) and worse patient survival rates (p = 0.0063) during the 3-year follow-up period compared with KTR without MACE. After adjustment, the independent significant factors for MACE were arrhythmia (HR 2.511, p = 0.02, 95% CI 1.158-5.444), pretransplant history of acute myocardial infarction (HR 0.201, p = 0.046, 95% CI 0.042-0.970), and pretransplant myocardial revascularization (HR 0.225, p = 0.045, 95% CI 0.052-0.939).

Conclusion

Asymptomatic CVD is largely prevalent in KTR. Posttransplant MACE has a negative effect on grafts and patient outcomes. Further research is needed to assess the benefits of pretransplant myocardial revascularization in asymptomatic kidney transplant candidates.

Diagnostic accuracy of myocardial perfusion imaging in patients evaluated for kidney transplantation: A systematic review and meta-analysis

BACKGROUND

Cardiovascular disease is the most common cause of death after kidney transplantation. Coronary artery disease (CAD) assessment is therefore mandatory in patients evaluated for transplantation. We aimed to assess the diagnostic accuracy for CAD of single-photon emission computed tomography (SPECT) compared to the standards invasive coronary angiography (ICA) and coronary computed tomography angiography (CCTA) in patients evaluated for kidney transplantation.

METHODS

We performed a systematic literature search in PubMed, EMBASE, Web of Science, OvidSP (Medline), The Cochrane Library and Google Scholar. Studies investigating the diagnostic accuracy of myocardial perfusion imaging (MPI) SPECT in patients evaluated for kidney transplantation were retrieved. After a risk of bias assessment using QUADAS-2, a meta-analysis was conducted.

RESULTS

Out of 1459 records, 13 MPI SPECT studies were included in the meta-analysis with a total of 1245 MPI SPECT scans. There were no studies available with CCTA as reference. Pooled sensitivity of MPI SPECT for CAD was 0.66 (95% CI 0.53 to 0.77), pooled specificity was 0.75 (95% CI 0.63 to 0.84) and the area under the curve (AUC) was 0.76. Positive likelihood ratio was 2.50 (95% CI 1.78 to 3.51) and negative likelihood ratio was 0.41 (95% CI 0.28 to 0.61). Pooled positive predictive value was 64.9% and pooled negative predictive value was 74.1%. Significant heterogeneity existed across the included studies.

CONCLUSIONS

MPI SPECT had a moderate diagnostic accuracy in patients evaluated for kidney transplantation, with a high rate of false-negative findings. The use of an anatomical gold standard against a functional imaging test in the included studies is however suboptimal.

Prognostic value of myocardial perfusion imaging in patients with chronic kidney disease: A systematic review and meta-analysis

BACKGROUND

We performed a systematic review and meta-analysis to investigate the prognostic value of stress myocardial perfusion single-photon emission computed tomography (MPS) in predicting adverse cardiovascular events in patients with chronic kidney disease (CKD).

METHODS

Studies published from inception until July 2020 were identified by PubMed and Embase databases search. Studies were included if they evaluated CKD patients referred for stress MPS, providing data on adjusted hazard ratio (HR) for the occurrence of adverse events. For studies providing only non-adjusted HR, the univariable risk estimate was included in the analysis. Pooled HR and 95% confidence interval (CI) were estimated using a random effects model to compare patients with abnormal and normal MPS. Whenever possible, incidence rate ratio (IRR) was also calculated and pooled.

RESULTS

Sixteen eligible studies were identified including 7834 patients with a follow-up range from 1 to 4.4 years. Eleven articles included patients with end-stage renal disease (IV-V CKD stage), 3 articles with III-V CKD stage and 2 articles with I-V CKD stage. The pooled HR for the occurrence of adverse events was 2.02 (95% CI 1.68-2.42) and heterogeneity was 34%. Among the included studies, 5 reported the HR for the occurrence of hard events, with a pooled HR of 2.36 (95% CI 1.77-3.13). A total of 8 studies reported data useful to calculate the IRR in patients with normal and abnormal perfusion. The pooled IRR was 2.37 (95% CI 1.63-3.47) and heterogeneity was 60%. At meta-regression analysis, we found an association between HR for adverse events and age, hypertension and smoking, while no significant association was found between HR for hard events and demographic and clinical variables.

CONCLUSIONS

In patients with CKD an abnormal myocardial perfusion at stress MPS is associated with adverse cardiovascular events.

Relation of abnormal cardiac stress testing with outcomes in patients undergoing renal transplantation

Cardiovascular risk stratification is often performed in patients considered for renal transplantation. In a single center, we sought to examine the association between abnormal stress testing with imaging and post-renal transplant major adverse cardiovascular events (MACE) using multivariable logistic regression. From January 2006 to May 2016 232 patients underwent renal transplantation and 59 (25%) had an abnormal stress test result. Compared to patients with a normal stress test, patients with an abnormal stress test had a higher prevalence of dyslipidemia, diabetes mellitus, obesity, coronary artery disease (CAD), and heart failure. Among those with an abnormal result, 45 (76%) had mild, 10 (17%) moderate, and 4 (7%) severe ischemia. In our cohort, 9 patients (3.9%) had MACE at 30-days post-transplant, 5 of whom had an abnormal stress test. The long-term MACE rate, at a median of 5 years, was 32%. After adjustment, diabetes (OR 2.37, 95% CI 1.12-5.00, p = 0.02), CAD (OR: 3.05, 95% CI 1.30-7.14, p = 0.01) and atrial fibrillation (OR: 5.86, 95% CI 1.86-18.44, p = 0.002) were independently associated with long-term MACE, but an abnormal stress test was not (OR: 0.83, 95% CI 0.37-1.92, p = 0.68). In conclusion, cardiac stress testing was not an independent predictor of long-term MACE among patients undergoing renal transplant.

KDOQI US Commentary on the 2020 KDIGO Clinical Practice Guideline on the Evaluation and Management of Candidates for Kidney Transplantation

Evaluation of patients for kidney transplant candidacy is a comprehensive process that involves a detailed assessment of medical and surgical issues, psychosocial factors, and patients' physical and cognitive abilities with an aim of balancing the benefits of transplantation and potential risks of surgery and long-term immunosuppression. There is considerable variability among transplant centers in their approach to evaluation and decision-making regarding transplant candidacy. The 2020 KDIGO (Kidney Disease: Improving Guidelines Outcome) clinical practice guideline on the evaluation and management of candidates for kidney transplantation provides practice recommendations that can serve as a useful reference guide to transplant professionals. The guideline, covering a broad range of topics, was developed by an international group of experts from transplant and nephrology through a review of literature published until May 2019. A work group of US transplant nephrologists convened by NKF-KDOQI (National Kidney Foundation-Kidney Disease Quality Initiative) chose key topics for this commentary with a goal of presenting a broad discussion to the US transplant community. Each section of this article has a summary of the key KDIGO guideline recommendations, followed by a brief commentary on the recommendations, their clinical utility, and potential implementation challenges. The KDOQI work group agrees broadly with the KDIGO recommendations but also recognizes and highlights the decision-making challenges that arise from lack of high-quality evidence and the need to balance equity with utility of organ transplantation.

Cardiac Risk Assessment in Kidney Transplant Candidates: Clinical Usefulness of Different Guidelines

Although cardiovascular (CV) assessment is recommended to minimize perioperative risk in all potential kidney transplant recipients, the utility and reliability of various assessment methods are not well established. In this study, we investigated the CV evaluations and outcomes of standardized CV assessment protocols (Lisbon and American Society of Transplantation [AST]) in potential kidney transplant recipients. Data were analyzed for 266 end-stage renal disease patients (mean age 45.4 ± 13 years, female-to-male ratio 126:140) accepted for kidney transplantation wait-listing. Patients were classified as low and high cardiac risk according to their first cardiac evaluation. Major cardiovascular events (CVEs) and deaths were recorded. At the end of follow-up (median 639 days), 72 (27.1%) patients underwent kidney transplantation. A total of 49 patients (18.4%) had CVEs and 42 (15.8%) patients died. Being over 45 years of age and having dialysis vintage over 1 year were found to be independent risk factors for CVEs. Forty-eight out of 60 high-risk patients evaluated with noninvasive tests had negative results. Twelve out of these 48 patients had a CVE in due course. Among 10 patients who underwent coronary angiography, 1 had a CVE and 1 died. The sensitivity and specificity of the AST guidelines (area under the curve = 0.647, P = .005, sensitivity 83%, specificity 54%) were higher than Lisbon. In conclusion, the predictive risk factors for CVEs were age over 45 years and dialysis vintage over a year. Our results also suggest that exercise electrocardiography and myocardial perfusion scintigraphy for cardiac evaluation are less sensitive in CVE prediction. We recommend clinicians to use the AST guidelines and to prioritize coronary angiography in pretransplant CV assessment.

Screening coronary angiography in patients with long-standing diabetes mellitus undergoing kidney transplant evaluation

BACKGROUND

The utility of coronary angiography in patients with diabetes mellitus undergoing kidney transplant evaluation is unclear. Predictors of critical angiography lesions in these patients will aid in appropriate use of angiography.

METHODS

Single-center study of 80 patients with ≥15 years of diabetes mellitus who underwent a screening coronary angiography despite a negative cardiac stress test. Risk factors for needing coronary intervention (CI) (percutaneous or bypass grafting) were analyzed.

RESULTS

Eighteen patients (23%) had a ≥70% occlusion in one or more major coronary vessel(s), with right coronary artery being the most commonly involved (71%). Fifteen patients (19%) underwent coronary intervention: ten percutaneously and five with bypass surgery. Risk factors for needing CI were not being on statin (OR 3.54, P = 0.047) and history of stroke or peripheral vascular disease (PVD; OR 3.5, P = 0.034). A model that included statin use, stroke/PVD history, and glycosylated hemoglobin had a receiver operating characteristic curve area under the curve of 0.8 to predict CI.

CONCLUSION

Despite a negative stress test, the prevalence of critical coronary lesions was high among kidney transplant candidates with long-standing diabetes. Risk factors for needing coronary intervention were absence of statin use and a history of stroke or peripheral vascular disease.

Clinical significance of multidetector coronary computed tomography angiography to evaluate the prevalence and severity of coronary artery disease in asymptomatic kidney transplantation recipients

BACKGROUND

Coronary artery disease (CAD) is one of the leading causes of mortality in kidney transplantation (KT) recipients. Noninvasive coronary angiography with the use of multidetector computerized tomography (MDCT) is feasible with high sensitivity and negative predictive value to evaluate CAD. However, few studies have been conducted to elucidate the applicability of MDCT in KT. This study was designed to evaluate the prevalence and severity of CAD with the use of MDCT angiography in asymptomatic KT recipients.

METHODS

From September 2011 to November 2013, MDCT angiography was performed on 90 renal transplant recipients who had no pre-transplantation CAD history and stabilized post-transplantation renal function for 6-18 months. According to the MDCT results, we divided our study population into 2 groups: The no-CAD group (n = 36; 40.0%) and the CAD group (n = 54; 60.0%). Severity of CAD was categorized as follows: mild CAD, 1 vessel obstructive, 2 vessels obstructive (or in the proximal left anterior descending), and 3 vessels obstructive (or left main).

RESULTS

Among the risk factors, pre-transplantation diabetes mellitus and lower levels of high-density lipoprotein, higher parathyroid hormone levels, higher coronary artery calcification scores, and rejection episodes were independent factors for CAD. Thirty-two (59.3%) of the CAD group had mild obstructive lesions and 22 (40.7%) had obstructive lesions in >1 vessel according to MDCT angiography.

CONCLUSIONS

MDCT angiography is a useful and noninvasive method for detecting CAD even in asymptomatic KT recipients.

Inactivity on the kidney transplant wait-list is associated with inferior pre- and post-transplant outcomes

BACKGROUND

The majority of kidney transplant (KT) candidates spend some time on the transplant wait-list (WL) prior to kidney transplantation. We examined the impact of WL inactivity on clinical outcomes.

METHODS

All adult KT candidates first actively wait-listed between January 1, 1996, and December 31, 2005, in the United States were grouped by frequency of inactivity on the WL. Transplantation rate, pre- and post-transplant patient survival and death-censored kidney graft survival were compared.

RESULTS

Of 159,774 candidates who were placed on the WL, 48,598 (30.4%) experienced one or more periods of inactivity. Candidates with inactivity once or more on the WL had 42% and 27% less likelihood of KT, respectively (HR 0.58, 95% CI 0.57, 0.59 and HR 0.73, 95% CI 0.71, 0.75). WL inactivity once or more was associated with a higher likelihood of death (HR 1.94, 95% CI 1.88, 2.00 and HR 2.13, 95% CI 2.02, 2.24). Among KT recipients, inactivity more than once on the WL was associated with a higher risk of death (HR 1.14, 95% CI 1.05, 1.23).

CONCLUSIONS

Periods of inactivity on the WL predict increased mortality pre- and post-transplantation. A better understanding of the reasons for WL inactivity is essential to improve WL management and post-transplant outcomes.

Ischemic heart disease in patients undergoing dialysis

Cardiovascular disease is the most common cause of death in patients with end-stage renal disease (ESRD) who are undergoing chronic dialysis. Diabetes and hypertension, the 2 leading causes of ESRD, contribute to the pathogenesis of ischemic heart disease (IHD) in these patients, as do other traditional risk factors (eg, dyslipidemias, smoking, and sedentary lifestyle). However, patients with ESRD are subject to several unique risk factors that contribute to the development and progression of IHD. Chronic volume overload and anemia, leading to left ventricular hypertrophy, and deranged calcium-phosphate metabolism with vascular and coronary calcification, contribute to the pathogenesis of IHD. Other risk factors that have been implicated include oxidative stress, homocysteine, and myocardial stunning while undergoing dialysis treatment. Additional risk factors include erythropoietin use for treating anemia, as well as use of calcium-based phosphate binders. The complex pathogenesis of IHD in such patients poses unique challenges to its management. Serological biomarkers and sophisticated imaging techniques are being developed to better delineate the pathological process and enhance disease detection. A combination of medical and surgical approaches is necessary to treat IHD. In this article, we discuss the pathogenesis and management of IHD.

Cardiac risk assessment by gated single-photon emission computed tomography in asymptomatic end-stage renal disease patients at the start of dialysis

OBJECTIVES

This study assessed the impact of cardiac risk assessment using gated single-photon emission computed tomography (SPECT) on cardiac events in end-stage renal disease (ESRD) patients.

METHODS

We evaluated 215 asymptomatic patients who began dialysis between January 2005 and April 2009. Baseline electrocardiography and echocardiography were performed in all the patients. The subjects were stratified into low- and high-risk groups according to the baseline cardiac status, and gated SPECT was additionally recommended for the high-risk patients.

RESULTS

The study population consisted of 50 low- and 165 high-risk patients undergoing SPECT. Among the high-risk patients, 75 (45.5%) showed perfusion defects on SPECT and their overall cardiac-event rate per person-year of follow-up was 15.0%, significantly higher than 4.5% in high-risk group without perfusion defect and 1.2% in low-risk group. The presence of perfusion defect was a significant independent predictor of adverse cardiac events [hazard ratio (HR) 2.11; 95% confidence interval (CI) 1.05-4.24; P = .035]. When gated SPECT was added to the clinical and the echocardiographic variables, the prognostic stratification significantly improved (P < .001). However, coronary revascularization was not associated with improved cardiac event-free survival (HR 0.62; 95% CI 0.26-1.52; P = .296).

CONCLUSIONS

Gated SPECT may provide additional prognostic information for cardiac risk stratification, particularly among high-risk patients starting dialysis.

Myocardial microvascular disease and major adverse cardiovascular events in patients with end-stage renal disease: rationale and design of the MICROCARD study

BACKGROUND

Myocardial ischaemia, a consequence of coronary artery disease, is a major cause of death in patients with end-stage renal disease (ESRD). The pathophysiology and clinical presentation of coronary artery disease in ESRD patients seem to differ from non-ESRD patients with higher implication of myocardial microvascular disease (MMD), higher mortality, fewer myocardial infarctions, less significant coronary stenosis and low efficacy of well-established drugs such as statin and angiotensin-converting enzyme inhibitors. No study has investigated the presence of MMD and its clinical impact in ESRD patients.

METHODS

We designed an observational prospective cohort study to investigate the prevalence of MMD and its association with major adverse cardiovascular events (MACE) in ESRD patients with a positive non-invasive test for myocardial ischaemia. Patients eligible for inclusion are those>18 years old receiving dialysis and/or undergoing investigation for kidney transplantation, who are referred to our renal clinic and meet all the inclusion criteria but none of the exclusion criteria. Patients with a positive test for myocardial ischaemia will be enrolled in the 'invasive group'. They will be further examined to detect simultaneously epicardial coronary stenosis by coronary angiography and MMD using pressure wire measurement of fractional flow reserve and coronary flow reserve followed by calculation of the index of microcirculatory resistance. Patients with a negative test for myocardial ischaemia will be enrolled in a 'control group' designed to verify whether the invasive group is indeed at high risk for MACE. Both groups will be followed up for 2 years to compare the incidence of MACE.

CONCLUSION

The MICROCARD study will phenotype MMD and will investigate its relation with the incidence of MACE in ESRD patients with myocardial ischaemia. Clinicaltrial.gov NCT01291771.

Is standardized cardiac assessment of asymptomatic high-risk renal transplant candidates beneficial?

BACKGROUND

Perioperative cardiovascular events in renal transplantation are common and non-invasive cardiac stress tests are recommended in high-risk renal transplant candidates. In 2004, we introduced a standardized preoperative cardiac risk assessment programme with the aim of reducing perioperative cardiac events.

METHODS

Since 2004, all asymptomatic high-risk renal transplant candidates had to undergo non-invasive cardiac stress testing. Patients with a positive stress test went for a coronary angiography and if indicated for revascularization. The incidence of perioperative cardiac events (≤30 days of transplantation) was analysed in all high-risk patients who received a transplantation (screening group) and compared with high-risk renal transplant recipients evaluated in the 4 years before the introduction of the cardiac assessment programme (historical control group).

RESULTS

Since 2004, 227 of 349 asymptomatic high-risk renal transplant candidates underwent non-invasive cardiac stress testing. In 15 patients (6.6%), significant ischaemia was found. Ten of these 15 patients underwent coronary angiography (eight patients had significant coronary artery disease and in five patients, percutaneous coronary intervention was performed). One hundred and sixty of 349 renal transplant candidates have received renal transplantation so far (screening group). In the screening group, 6 perioperative cardiac events (3.8%) occurred compared to 13 perioperative events (7.6%) in the historical control group (n = 172) (P = 0.136).

CONCLUSIONS

The incidence of significant cardiac ischaemia in high-risk renal transplant patients was low and was followed by revascularization in a small percentage of patients. No significant decrease in perioperative cardiac events was observed after the introduction of the standardized cardiac assessment programme.