Prediction of cardiovascular events in pre-dialysis chronic kidney disease patients with normal SPECT myocardial perfusion imaging. J Cardiol. 2014;63:154-158. [PMID: 24001741 DOI: 10.1016/j.jjcc.2013.07.011]

Noninvasive Diagnosis of Kidney Dysfunction Using a Small-Molecule Manganese-Based Magnetic Resonance Imaging Probe

Contrast-enhanced magnetic resonance imaging (CE-MRI) is a promising approach for the diagnosis of kidney diseases. However, safety concerns, including nephrogenic systemic fibrosis, limit the administration of gadolinium (Gd)-based contrast agents (GBCAs) in patients who suffer from renal impairment. Meanwhile, nanomaterials meet biosafety concerns because of their long-term retention in the body. Herein, we propose a small-molecule manganese-based imaging probe Mn-PhDTA as an alternative to GBCAs to assess renal insufficiency for the first time. Mn-PhDTA was synthesized via a simple three-step reaction with a total yield of up to 33.6%, and a gram-scale synthesis can be realized. Mn-PhDTA has an r1 relaxivity of 2.72 mM-1 s-1 at 3.0 T and superior kinetic inertness over Gd-DTPA and Mn-EDTA with a dissociation time of 60 min in the presence of excess Zn2+. In vivo and in vitro experiments demonstrate their good stability and biocompatibility. In the unilateral ureteral obstruction rats, Mn-PhDTA provided significant MR signal enhancement, enabled distinguishing structure changes between the normal and damaged kidneys, and evaluated the renal function at different injured stages. Mn-PhDTA could act as a potential MRI contrast agent candidate for the replacement of GBCAs in the early detection of kidney dysfunction and analysis of kidney disease progression.

Detection of Kidney Dysfunction through In Vivo Magnetic Resonance Imaging with Renal-Clearable Gadolinium Nanoprobes

Kidney dysfunction is a clinical syndrome that can subsequently result in lethal kidney failure. The exploration of emerging bioimaging contrast agents with translational potential is highly challenging for a feasible diagnosis of kidney dysfunction. Herein, a class of renal-clearable gadolinium nanoparticles (Gd@PEG NPs) with an ultrasmall size of ∼5 nm, good monodispersity, and T₁ relaxivity are synthesized using mesoporous silica nanoparticles as the template. Assisted by such renal-clearable Gd@PEG NPs, the diagnosis of kidney dysfunction in a mice model with a damaged kidney has been achieved through in vivo noninvasive magnetic resonance imaging. As a result, this work paves the way to synthesize monodispersible ultrasmall Gd contrast agents, facilitating the exploration of translational strategies for an in vivo analysis of kidney dysfunction.

Diabetic patients with chronic kidney disease: Non-invasive assessment of cardiovascular risk

The prevalence and burden of diabetes mellitus and chronic kidney disease on global health and socioeconomic development is already heavy and still rising. Diabetes mellitus by itself is linked to adverse cardiovascular events, and the presence of concomitant chronic kidney disease further amplifies cardiovascular risk. The culmination of traditional (male gender, smoking, advanced age, obesity, arterial hypertension and dyslipidemia) and non-traditional risk factors (anemia, inflammation, proteinuria, volume overload, mineral metabolism abnormalities, oxidative stress, etc.) contributes to advanced atherosclerosis and increased cardiovascular risk. To decrease the morbidity and mortality of these patients due to cardiovascular causes, timely and efficient cardiovascular risk assessment is of huge importance. Cardiovascular risk assessment can be based on laboratory parameters, imaging techniques, arterial stiffness parameters, ankle-brachial index and 24 h blood pressure measurements. Newer methods include epigenetic markers, soluble adhesion molecules, cytokines and markers of oxidative stress. In this review, the authors present several non-invasive methods of cardiovascular risk assessment in patients with diabetes mellitus and chronic kidney disease.

Incremental prognostic value of SPECT-MPI in chronic kidney disease: A reclassification analysis

BACKGROUND

Traditional cardiovascular (CV) risk factors have limited predictive value of CV mortality in patients with chronic kidney disease (CKD, creatinine clearance less than 60 mL/minute per 1.73 m2). The aim of this study was to evaluate incremental and independent prognostic value of single-photon emission computerized tomography-myocardial perfusion imaging (SPECT-MPI) across continuum of renal function.

METHODS

We retrospectively studied 11,518 (mean age, 65 ± 12 years; 52% were men) patients referred for a clinical indication of SPECT-MPI between April 2004 and May 2009. Primary end point was composite of cardiac death and non-fatal myocardial infarction (CD/MI). We examined the relationship of total perfusion defect (TPD) and CD/MI in multiple Cox regression models for CV risk factors and GFR. The incremental predictive value of TPD was examined using Harrell's c-index, net reclassification index (NRI), and integrated discrimination index (IDI).

RESULTS

Over a median follow-up of 5 years (25th to 75th percentiles, 3.0-6.5 years), 1,692 (14.5%) patients experienced CD/MI (740 MI and 1,182 CD). In a multivariable model adjusted for traditional CV risk factors and GFR, the presence of a perfusion defect was independently associated with increased risk of CD/MI (HR = 2.10; 95% CI 1.81, 2.43, p < .001). Using Cox regression, TPD improved the discriminatory ability beyond traditional CV risk factors and GFR [from AUC = 0.725, (95% CI 0.712-0.738) to 0.784, (95% CI 0.772-0.796), p < .0001]. Furthermore, TPD improves risk stratification of CKD patients over and above traditional CV risk factors and GFR [NRI = 14%, 95% CI (12%-16%, p < .001) and relative IDI = 60%, 95% CI (51%, 66%, p < .001)].

CONCLUSIONS

Across the spectrum of renal function, SPECT-MPI perfusion defects independently and incrementally reclassified patients for their risk of CD/MI, beyond traditional CV risk factors.

The relationship of renal function to segmental vascular stiffness, ankle-brachial index, and peripheral artery disease

The authors consecutively assessed various arterial pulse-wave velocity (PWV) indices and ankle-brachial index (ABI) by an automatic device (VP2000, OMRON Health Care Co. Ltd., Kyota, Japan) in outpatients with ≥ 1 cardiovascular risk. PAD was defined as ABI ≤ 0.9. Among 2309 outpatients (mean age 62.4 years), worse renal function was associated with higher brachial-ankle PWV, heart-carotid PWV, heart-femoral PWV (hf-PWV), and lower ABI (all P < .001). Multivariate regression models showed independent associations between lower eGFR, lower ABI (Coef: 0.42 & 0.41 for right and left), higher hf-PWV (Coef: -11.4 [95% CI: -15.4, -7.3]) and greater PAD risk (adjusted OR: 0.83 [95% CI: 0.76, 0.91], all P < .05). eGFR set at 77 mL/min/1.73m² was observed to be useful clinical cutoff (c-statistics: 0.67) for identifying PAD (P for ΔAUROC: .009; likelihood X² : 93.82 to 137.43, P < .001) when superimposed on clinical risks. This study suggested early renal insufficiency is tightly linked to region-specific vascular stiffness and PAD.

Ability of the prognostic model of J-ACCESS study to predict cardiac events in a clinical setting: The APPROACH study

BACKGROUND

In patients with coronary artery disease (CAD), one of the risk models available in Japan was a multivariate risk prediction model based on a Japanese multicenter database: the Japanese Assessment of Cardiac Events and Survival Study by Quantitative Gated SPECT (J-ACCESS). The aim of this study was to clinically validate the accuracy of this risk model.

METHODS

We evaluated the performance of the J-ACCESS model using data derived from the Assessment of the Predicted value of PROgnosis of cArdiaC events in Hokuriku (APPROACH) registry. Variables of age, summed stress score (SSS), left ventricular ejection fraction (LVEF), estimated glomerular filtration rate (eGFR), and diabetes mellitus were included. The major cardiac events were defined as cardiac death, non-fatal myocardial infarction, and heart failure that required hospitalization. The patients were followed up for three years to compare between predicted risk and actual events.

RESULTS

We evaluated 283 patients with suspected or confirmed CAD receiving myocardial perfusion imaging using ^99mTc-tetrofosmin between March 2009 and August 2011. Mean age was 68.9±10.1 years, mean eGFR 67.4±24.3mL/min/1.73m², mean SSS 5.2±7.2, and mean LVEF 65.4±14.0%. Fourteen (4.9%) patients experienced major cardiac events including cardiac death in 4 patients (1.4%), non-fatal myocardial infarction in 1 patient (0.3%), and severe heart failure in 9 patients (3.2%), respectively. While SSS≥8, LVEF<50%, eGFR<45mL/min/1.73m², and event risk≥10% were significant variables in survival analysis, multivariate proportional hazard analysis showed that only LVEF and eGFR were significant. The event rate estimated from the J-ACCESS model was comparable to the actual number of major cardiac events (9 and 6, respectively, p=0.58 by Chi-square test).

CONCLUSIONS

The predictive ability of the J-ACCESS risk model is clinically valid among patients with CAD and could be applicable in clinical practice.

Myocardial Ischemia Assessment in Chronic Kidney Disease: Challenges and Pitfalls

Coronary artery disease is the leading cause of mortality and morbidity in the chronic kidney disease (CKD) population and often presents with atypical symptoms. Current diagnostic investigations of myocardial ischemia in CKD lack sensitivity and specificity or may have adverse effects. We present a case vignette and explore the challenges of diagnostic myocardial stress investigation in patients with CKD.