A cardiac magnetic resonance imaging study of long-term and incident hemodialysis patients

Cardiac Magnetic Resonance Imaging Findings in Patients With Chronic Kidney Disease and End-Stage Kidney Disease: A Systematic Review and Meta-Analysis

In this systematic review and meta-analysis, we explored the utilization of cardiac magnetic resonance imaging (CMR) to detect fibrotic changes secondary to uremic cardiomyopathy during the early stages of chronic kidney disease (CKD) and in patients with end-stage kidney disease (ESKD). Uremic myocardial fibrosis can lead to arrhythmia and heart failure, and it is important to detect these changes. CMR offers a noninvasive way to characterize the severity of cardiac remodeling. A comprehensive search of multiple electronic databases was conducted. Studies were divided according to scanner field strength (1.5 or 3 Tesla). The random effects model was used to calculate the pooled mean, 95% confidence interval (CI), standard error, and standardized mean difference (SMD). The I2 statistic was used to assess the heterogeneity between study-specific estimates. The search retrieved 779 studies. From these, 20 studies met the inclusion criteria and had 642 CKD patients (mean age of 56.8 years; 65.2% males; mean estimated glomerular filtration rate (eGFR) of 33 mL/min/1.73 m2) and 658 ESKD patients on dialysis (mean age of 55.6 years; 63.3% males; mean dialysis duration of 3.47 years). CKD patients had an increased left ventricular mass index (LVMi) compared to controls, with an SMD of 0.37 (95% CI: 0.20-0.54; I2 0%; p-value <0.05). ESKD patients also had increased LVMi compared to controls, SMD 0.88 (95% CI: 0.35-1.41; I2 79.1%; p-value 0.001). Myocardial fibrosis assessment using T1 mapping showed elevated values; the SMD of native septal T1 values between CKD and controls was 1.099 (95% CI: 0.73-1.46; I2 33.6%; p-value <0.05), and the SMD of native septal T1 values between ESKD patients and controls was 1.12 (95% CI: 0.85-1.38; I2 33.69%; p-value <0.05). In conclusion, patients with CKD and ESKD with preserved left ventricular ejection fraction (LVEF) have higher LVMi and T1 values, indicating increased mass and fibrosis. T1 mapping can be used for the early detection of cardiomyopathy and as a risk stratification tool. Large, randomized trials are needed to confirm these findings and determine the effect of long-term dialysis on cardiac fibrosis.

Value of native T1 mapping in the prediction of major adverse cardiovascular events in hemodialysis patients

OBJECTIVES

This study aimed to evaluate the association of myocardial characterization by native T1 mapping using cardiac MR (CMR) with the incidence of major adverse cardiovascular event (MACE) in end-stage renal dysfunction (ESRD) patients on hemodialysis.

METHODS

A total of 52 ESRD patients and 52 healthy individuals were prospectively recruited between June 2017 and June 2018. ESRD patients underwent CMR examinations post-hemodialysis for the evaluation of cardiac function and global native T1 mapping. Demographics, serum biomarkers, and coronary artery calcification were collected. MACE including all-caused death, and new onset of myocardial infarction, heart failure leading to hospitalization, fatal arrhythmia, and cardiac arrest was set as the endpoint.

RESULTS

During a median follow-up of 38.0 months, 13 patients (25.0%) reached the endpoints. Global native T1 mapping in patients on hemodialysis was significantly higher compared with that of healthy individuals (1280.3 ms ± 45.3 vs. 1238.2 ms ± 31.1, p < 0.001). In the univariate Cox regression analysis, global native T1 mapping (HR [hazard ratios]: 1.887, 95% CI [confidence interval]: 1.302-2.736, p = 0.001) was associated with the prediction of MACE. Multivariate Cox regression analysis demonstrated that global native T1 mapping (HR: 1.580, 95% CI: 1.112-2.244, p = 0.011) and age (HR: 1.088, 95% CI: 1.032-1.146, p = 0.002) were associated with the incidence of MACE after adjusting for other conventional risk factors.

CONCLUSIONS

Global native T1 mapping by CMR can potentially become a novel predictor of MACE in ESRD patients on hemodialysis, providing additional prognostic values over conventional risk factors. However, this conclusion should be validated in a larger sample size of hemodialysis patients.

KEY POINTS

• Global native T1 mapping was significantly higher in ESRD patients on hemodialysis compared with that of normal controls. • Global native T1 mapping was associated with myocardial enzymes, myocardial hypertrophy, coronary calcification, and cardiac function. • Global native T1 mapping value was independently predictive of MACE in hemodialysis patients, providing additional prognostic values over conventional risk factors.

Heart failure in chronic kidney disease: the emerging role of myocardial fibrosis

Heart failure (HF) is one of the main causes of morbidity and mortality in patients with chronic kidney disease (CKD). Decreased glomerular filtration rate is associated with diffuse deposition of fibrotic tissue in the myocardial interstitium [i.e. myocardial interstitial fibrosis (MIF)] and loss of cardiac function. MIF results from cardiac fibroblast-mediated alterations in the turnover of fibrillary collagen that lead to the excessive synthesis and deposition of collagen fibres. The accumulation of stiff fibrotic tissue alters the mechanical properties of the myocardium, thus contributing to the development of HF. Accumulating evidence suggests that several mechanisms are operative along the different stages of CKD that may converge to alter fibroblasts and collagen turnover in the heart. Therefore, focusing on MIF might enable the identification of fibrosis-related biomarkers and targets that could potentially lead to a new strategy for the prevention and treatment of HF in patients with CKD. This article summarizes current knowledge on the mechanisms and detrimental consequences of MIF in CKD and discusses the validity and usefulness of available biomarkers to recognize the clinical-pathological variability of MIF and track its clinical evolution in CKD patients. Finally, the currently available and potential future therapeutic strategies aimed at personalizing prevention and reversal of MIF in CKD patients, especially those with HF, will be also discussed.

Associations of B-type natriuretic peptide (BNP) and dialysis vintage with CMRI-derived cardiac indices in stable hemodialysis patients with a preserved left ventricular ejection fraction

To assess left ventricular myocardial native T1/T2 values and systolic strain and their associations with B-type natriuretic peptide (BNP) and dialysis vintage in hemodialysis (HD) patients with a preserved left ventricular ejection fraction (LVEF). Forty-three HD patients with end-stage renal disease (ESRD) but a preserved LVEF (≥ 50%) and 28 healthy volunteers were enrolled. BNP was measured at the time of cardiac magnetic resonance (CMR) measurements. Global native T1 and T2 values were significantly higher in the HD patients (native T1: 1056 ± 32 ms vs. 1006 ± 25 ms, p < 0.001; T2: 50 ± 3 ms vs. 46 ± 2 ms, p < 0.001) than in the controls. The mean peak global circumferential strain (GCS) and global longitudinal strain (GLS) were both significantly reduced in the HD patients compared with the controls (GCS: - 13 ± 3 vs. - 16 ± 3, p < 0.001; GLS: - 12 ± 4 vs. - 15 ± 3, p = 0.001). In the HD patients, the global native T1 value showed a positive correlation with the global T2 value (r = 0.311, p = 0.042) and significant correlations with GCS (r = 0.564, p < 0.001) and GLS (r = 0.359, p = 0.018). Significant positive correlations were found between lg BNP levels and T2 values (r = 0.569, p < 0.0001) and the left atrial volume index (LAVI) (r = 0.536, p = 0.012). GLS showed significant positive correlations with the LVMI (r = 0.354, p = 0.020) and dialysis vintage (p = 0.026; r = - 0.339) in the HD patients. HD patients with a preserved LVEF have increased native T1/T2 values and decreased strain compared to controls. T2 values and the LVAI were positively associated with BNP in HD patients.

Predictors of Change in Left-Ventricular Structure and Function in a Trial of Extended Hours Hemodialysis

BACKGROUND

Myocardial pathology is common in patients undergoing hemodialysis. To explore the effects of differing aspects of dialysis treatment on its evolution, we examined the impact of change in markers of volume status, hemodynamics and solute clearance on left ventricular (LV) parameters in a randomized trial of extended hours dialysis.

METHODS AND RESULTS

A Clinical Trial of IntensiVE (ACTIVE) Dialysis randomized 200 patients undergoing hemodialysis to extended dialysis hours (≥ 24 hours/week) or standard hours (12-18 hours/week) for 12 months. In a prespecified substudy, 95 participants underwent cardiac magnetic resonance imaging (CMR) at baseline and at the study's end. Generalized linear regression was used to model the relationship between changes in LV parameters and markers of volume status (normalized ultrafiltration rate and total weekly interdialytic weight gain), hemodynamic changes (systolic and diastolic blood pressure) and solute control (urea clearance, dialysis hours and phosphate). Randomization to extended hours dialysis was not associated with change in any CMR parameter. Reduction in ultrafiltration rate was associated with reduction in LV mass index (P = 0.049) and improved ejection fraction (P = 0.024); reduction in systolic blood pressure was also associated with improvement in ejection fraction (P = 0.045); reduction in interdialytic weight gain was associated with reduced stroke volume (P = 0.038). There were no associations between change in urea clearance, phosphate or total hours per week and CMR parameters.

CONCLUSIONS

Reduction in ultrafiltration rate and blood pressure are associated with improved myocardial parameters in hemodialysis recipients independently of solute clearance or dialysis time. These findings underscore the importance of fluid status and related parameters as potential treatment targets in this population.