Subclinical markers of cardiovascular disease predict adverse outcomes in chronic kidney disease patients with normal left ventricular ejection fraction

Cardiac Imaging Biomarkers in Chronic Kidney Disease

Uremic cardiomyopathy (UC), the peculiar cardiac remodeling secondary to the systemic effects of renal dysfunction, is characterized by left ventricular (LV) diffuse fibrosis with hypertrophy (LVH) and stiffness and the development of heart failure and increased rates of cardiovascular mortality. Several imaging modalities can be used to obtain a non-invasive assessment of UC by different imaging biomarkers, which is the focus of the present review. Echocardiography has been largely employed in recent decades, especially for the determination of LVH by 2-dimensional imaging and diastolic dysfunction by pulsed-wave and tissue Doppler, where it retains a robust prognostic value; more recent techniques include parametric assessment of cardiac deformation by speckle tracking echocardiography and the use of 3D-imaging. Cardiac magnetic resonance (CMR) imaging allows a more accurate assessment of cardiac dimensions, including the right heart, and deformation by feature-tracking imaging; however, the most evident added value of CMR remains tissue characterization. T1 mapping demonstrated diffuse fibrosis in CKD patients, increasing with the worsening of renal disease and evident even in early stages of the disease, with few, but emerging, prognostic data. Some studies using T2 mapping highlighted the presence of subtle, diffuse myocardial edema. Finally, computed tomography, though rarely used to specifically assess UC, might provide incidental findings carrying prognostic relevance, including information on cardiac and vascular calcification. In summary, non-invasive cardiovascular imaging provides a wealth of imaging biomarkers for the characterization and risk-stratification of UC; integrating results from different imaging techniques can aid a better understanding of the physiopathology of UC and improve the clinical management of patients with CKD.

A comparative analysis of conventional and speckle-tracking strain echocardiographic findings in diabetic and non-diabetic kidney disease patients with normal ejection fraction

This study aimed to compare the differences in echocardiographic and strain parameters in patients with diabetic kidney disease (DKD) and non-diabetic kidney disease (NDKD) in a cohort with pre-dialysis chronic kidney disease (CKD) and normal ejection fraction (EF). In this single-center prospective study, patients with CKD stages 3-5 and EF > 55% were included. We compared cardiac structure and function using conventional and speckle-tracking strain echocardiography among DKD and NDKD groups. Cardiovascular outcomes were assessed at the end of the study. Of the included 117 patients, 56 (47.9%) had DKD, and 61 (52.1%) had NDKD. Patients with DKD had higher ratios of early mitral inflow velocity and mitral annular early diastolic velocity (E/e') (11.9 ± 4.4 vs. 9.8 ± 3.5; p = 0.004), lower septal e' velocity (7.1 ± 2.5 vs. 8.2 ± 2.8; p = 0.031), lower lateral e' velocity (9.2 ± 2.9 vs. 10.4 ± 3.8; p = 0.045) and longer deceleration times (209.2 ± 41.5 vs. 189.1 ± 48.0; p = 0.017), compared to those with NDKD. Left ventricular mass index (LVMI), global longitudinal strain (GLS), early diastolic strain rate (SR_E), and E/SR_E were similar. At a median follow-up of 239 days, 3-P MACE (11.5% vs. 4.9%; p = 0.047) and 4-P MACE (28.6% vs. 11.5%; p = 0.020) were observed to be higher in the DKD group. Diastolic dysfunction was more common in patients with DKD, compared to those with NDKD, although both groups had similar LVMI and GLS. Those with DKD also had poorer cardiovascular outcomes. This highlights the importance of the assessment of diastolic function in CKD, particularly in those with diabetic CKD.

Association Between Indoxyl Sulfate and Dialysis Initiation and Cardiac Outcomes in Chronic Kidney Disease Patients

Introduction

Indoxyl sulfate, a protein-bound uremic toxin, has been reported as an atherosclerosis and fibrosis accelerator. This study aimed to determine whether serum indoxyl sulfate is associated with cardiac abnormalities, cardiovascular events, and renal progression to dialysis in patients with chronic kidney disease (CKD).

Methods

The prospective study enrolled 89 patients with CKD stage 3 to 5 patients. Serum biochemistry data and indoxyl sulfate were measured. All patients underwent echocardiographic examination. Global longitudinal strain (GLS) was calculated using two-dimensional speckle tracking. The clinical outcomes including cardiovascular event and dialysis initiation were recorded during a 2-year follow-up.

Results

Patients were divided into 2 groups based on the median value of serum indoxyl sulfate (low and high indoxyl sulfate groups). Kaplan–Meier analysis revealed that patients with higher indoxyl sulfate (≥6.124 mg/L) were significantly associated with renal progression to dialysis (p < 0.001). There was no significant difference in cardiovascular events between 2 groups (p = 0.082). In addition, serum indoxyl sulfate level was independently associated with GLS (r = 0.62; p = 0.01). The risk of cardiovascular events was significantly higher in patients with impaired GLS (>−16%) (p = 0.015).

Conclusion

Serum indoxyl sulfate level was a significant predictor for CKD progression to dialysis and was correlated with GLS, a speckle tracking echocardiography parameter representing early LV systolic dysfunction. Furthermore, GLS was associated with cardiovascular events in CKD patients. Serum indoxyl sulfate measurement may help to identify the high dialysis and cardiovascular risk CKD patients beyond traditional risk factors.

Association of left ventricular hypertrophy and functional impairment with cardiovascular outcomes and mortality among patients with chronic kidney disease, results from the C-STRIDE study

AIM

Left ventricular hypertrophy and impaired systolic and diastolic function are commonly seen in patients with chronic kidney disease (CKD), but relationships between the disorders and cardiovascular outcomes are not well established among the patients.

METHODS

Totally, 2020 patients with CKD Stages 1-4 were used in the analysis. Left ventricular hypertrophy was defined by left ventricular mass index >49.2 g/m^2.7 in men and > 46.7 g/m^2.7 in women. Incident heart failure, non-heart failure cardiovascular events, and all-cause mortality were recorded longitudinally. Cox proportional hazards regression model was used to evaluate the association between the echo parameters and the outcomes, with death treated as the competing risk event for the cardiovascular events.

RESULTS

After a median follow-up of 4.5 years, 53 heart failure, 76 non-heart failure cardiovascular events and 82 deaths occurred. No overall association was found between left ventricular hypertrophy and subsequent heart failure, but the relationship was significant among patients with no diabetes with the multivariable adjusted hazard ratio of 3.66 (95% confidence interval: 1.42-9.46). Ejection fraction<55% was associated with both heart failure and non-heart failure cardiovascular events with hazard ratios of 3.16 (1.28-7.77) and 2.76 (1.08-7.04), respectively. E/A ratio ≤ 0.75 was associated with non-heart failure cardiovascular events [hazard ratio = 2.03 (1.09-3.80)], compared with E/A ratio of 0.76-1.49.

CONCLUSION

Associations of reduced left ventricular ejection fraction with both heart failure and non-heart failure cardiovascular events and of impaired left ventricular diastolic function with non-heart failure cardiovascular events were validated in a Chinese cohort of CKD.

Cardiac mechanics and incident ischemic stroke: the Cardiovascular Health Study

Recent evidence indicates that our understanding of the relationship between cardiac function and ischemic stroke remains incomplete. The Cardiovascular Health Study enrolled community-dwelling adults ≥ 65 years old. We included participants with speckle-tracking data from digitized baseline study echocardiograms. Exposures were left atrial reservoir strain (primary), left ventricular longitudinal strain, left ventricular early diastolic strain rate, septal e’ velocity, and lateral e’ velocity. The primary outcome was incident ischemic stroke. Cox proportional hazards models were adjusted for demographics, image quality, and risk factors including left ventricular ejection fraction and incident atrial fibrillation. Among 4,000 participants in our analysis, lower (worse) left atrial reservoir strain was associated with incident ischemic stroke (HR per SD absolute decrease, 1.14; 95% CI 1.04–25). All secondary exposure variables were significantly associated with the outcome. Left atrial reservoir strain was associated with cardioembolic stroke (HR per SD absolute decrease, 1.42; 95% CI 1.21–1.67) and cardioembolic stroke related to incident atrial fibrillation (HR per SD absolute decrease, 1.60; 1.32–1.95). Myocardial dysfunction that can ultimately lead to stroke may be identifiable at an early stage. This highlights opportunities to identify cerebrovascular risk earlier and improve stroke prevention via therapies for early myocardial dysfunction.

Feature-tracking cardiac magnetic resonance left ventricular global longitudinal strain improves 6 months after kidney transplantation associated with reverse remodeling, not myocardial tissue characteristics

To determine whether left ventricular (LV) global longitudinal strain (GLS) measured by feature-tracking (FT) cardiac magnetic resonance (CMR) improves after kidney transplantation (KT) and to analyze associations between LV GLS, reverse remodeling and myocardial tissue characteristics. This is a prospective single-center cohort study of kidney transplant recipients who underwent two CMR examinations in a 3T scanner, including cines, tagging, T1 and T2 mapping. The baseline exam was done up to 10 days after transplantation and the follow-up after 6 months. Age and sex-matched healthy controls were also studied for comparison. A total of 44 patients [mean age 50 ± 11 years-old, 27 (61.4%) male] completed the two CMR exams. LV GLS improved from - 13.4% ± 3.0 at baseline to - 15.2% ± 2.7 at follow-up (p < 0.001), but remained impaired when compared with controls (- 17.7% ± 1.5, p = 0.007). We observed significant correlation between improvement in LV GLS with reductions of left ventricular mass index (r = 0.356, p = 0.018). Improvement in LV GLS paralleled improvements in LV stroke volume index (r = - 0.429, p = 0.004), ejection fraction (r = - 0.408, p = 0.006), global circumferential strain (r = 0.420, p = 0.004) and global radial strain (r = - 0.530, p = 0.002). There were no significant correlations between LV GLS, native T1 or T2 measurements (p > 0.05). In this study, we demonstrated that LV GLS measured by FT-CMR improves 6 months after KT in association with reverse remodeling, but not native T1 or T2 measurements.

Speckle-tracking echocardiography in comparison with ejection fraction for prediction of cardiovascular mortality in patients with end-stage renal disease

Background

Cardiovascular disease is the major cause of death in end-stage renal disease (ESRD). To develop better means to assess cardiovascular risk in these patients, we compared conventional echocardiography-derived left ventricular ejection fraction (EF) with the novel method of 2D speckle-tracking echocardiography to determine cardiac strain.

Methods

Predictive performances of conventional EF and speckle-tracking echocardiography-derived global longitudinal strain (GLS) were compared using receiver-operator curve (ROC) analyses and calibration by calibration plots. We also took into account other known cardiovascular risk factors through multivariable logistic regression analysis.

Results

The study comprised 171 ESRD patients (mean age 64 years, 64% male) on maintenance dialysis therapy (93% haemodialysis, 7% peritoneal dialysis) for an average period of 39 months. During 2.1 years of follow-up, 42 patients (25%) died from cardiovascular disease. ROC analysis of GLS resulted in an area under the curve of 0.700 [95% confidence interval (CI) 0.603–0.797] compared with an area under the curve of EF of 0.615 (95% CI 0.514–0.716) (P = 0.059 for difference). The total absolute deviation between predicted and observed outcome frequencies obtained by calibration plots were 13.8% for EF compared with only 6.4% for GLS. Best results of ROC analysis (area under the curve = 0.759; P = 0.06), calibration and goodness-of-fit (χ² = 28.34, P ≤ 0.0001, R² = 0.25) were achieved for GLS added to a baseline model consisting of known cardiovascular risk factors in a multivariate regression analysis.

Conclusions

In summary, in chronic dialysis patients, GLS is a more precise predictor of cardiovascular mortality than conventional echocardiography-derived EF.

Prognostic models for chronic kidney disease: a systematic review and external validation

BACKGROUND

Accurate risk prediction is needed in order to provide personalized healthcare for chronic kidney disease (CKD) patients. An overload of prognosis studies is being published, ranging from individual biomarker studies to full prediction studies. We aim to systematically appraise published prognosis studies investigating multiple biomarkers and their role in risk predictions. Our primary objective was to investigate if the prognostic models that are reported in the literature were of sufficient quality and to externally validate them.

METHODS

We undertook a systematic review and appraised the quality of studies reporting multivariable prognosis models for end-stage renal disease (ESRD), cardiovascular (CV) events and mortality in CKD patients. We subsequently externally validated these models in a randomized trial that included patients from a broad CKD population.

RESULTS

We identified 91 papers describing 36 multivariable models for prognosis of ESRD, 50 for CV events, 46 for mortality and 17 for a composite outcome. Most studies were deemed of moderate quality. Moreover, they often adopted different definitions for the primary outcome and rarely reported full model equations (21% of the included studies). External validation was performed in the Multifactorial Approach and Superior Treatment Efficacy in Renal Patients with the Aid of Nurse Practitioners trial (n = 788, with 160 events for ESRD, 79 for CV and 102 for mortality). The 24 models that reported full model equations showed a great variability in their performance, although calibration remained fairly adequate for most models, except when predicting mortality (calibration slope >1.5).

CONCLUSIONS

This review shows that there is an abundance of multivariable prognosis models for the CKD population. Most studies were considered of moderate quality, and they were reported and analysed in such a manner that their results cannot directly be used in follow-up research or in clinical practice.

Prognostic value of left ventricular global longitudinal strain in chronic kidney disease patients: a systematic review and meta-analysis

OBJECTIVE

The objective of this meta-analysis was to evaluate whether left ventricular global longitudinal strain (GLS) is a potential marker of predicting adverse outcomes in CKD patients.

BACKGROUND

CKD is a growing health burden currently affecting 10-15% of adults worldwide, and disproportionally increasing propensity to develop cardiovascular diseases and events. Although obtained from several relatively small studies, the evidence supporting the prognostic value of GLS in patients with CKD is still building.

METHODS

We conducted a Medline literature research using electronic databases (PubMed, Ovid, Embase and Web of Science) to identify relevant studies reporting the association between GLS and the primary outcomes, including all-cause mortality, major cardiac events (MCE), and cardiovascular mortality in CKD patients. Sensitivity analysis and subgroup analysis were performed to find the origin of heterogeneity.

RESULTS

A total of 11 observational studies with 2167 patients with CKD were enrolled. In patients with CKD, GLS was associated with all-cause mortality (HR: 1.09, 95% CI 1.06-1.12) with no heterogeneity among the studies (I² = 46.5%, P = 0.06). In addition, GLS was associated with MCE and cardiovascular mortality with no heterogeneity (HR 1.16, 95% CI 1.11-1.22; HR 1.18, 95% CI 1.12-1.24, respectively). Overall, GLS was also associated with combined adverse events in CKD patients (HR 1.09, 95% CI 1.07-1.12) with moderate heterogeneity (I² = 51.2%, P = 0.025).

CONCLUSIONS

Our meta-analysis demonstrates that GLS is associated with all-cause mortality, MCE, cardiovascular mortality, and combined adverse events in CKD patients.

Cardiac Abnormalities in Children with Autosomal Recessive Polycystic Kidney Disease

BACKGROUND

No previous study has defined the prevalence of cardiac geometric and mechanical function abnormalities through the analysis of advanced echocardiographic parameters in children with autosomal recessive polycystic kidney disease (ARPKD).

AIM

The purpose of this study was to evaluate cardiac geometry and function through advanced echocardiography in a well-characterized sample of pediatric patients with ARPKD.

METHODS

Standard echocardiograms were obtained in 27 children with ARPKD (0-18 years) and in 88 healthy children of similar age, gender distribution, and body build. Left ventricular (LV) hypertrophy was defined as LV mass > 45g/(m2.16 + 0.09) and cardiac remodeling was defined by age-adjusted relative wall thickness (RWT). Systolic function was assessed by ejection fraction, midwall fractional shortening (mFS), and global longitudinal (GLS) and circumferential strain (GCS).

RESULTS

Patients with ARPKD exhibited a higher LV mass index as compared to controls, and a more concentric LV geometry (both p < 0.001). Accordingly, the prevalence of abnormal LV geometry was significantly higher in ARPKD (33 vs. 0%; p < 0.005). No differences could be observed in the two groups for ejection fraction or GLS (both p = n.s.), while a significantly lower mFS (p < 0.05) as well as GCS (p < 0.001) could be observed. In the analysis of covariance, both LV mass index and RWT remained significantly higher in the ARPKD group, while mFS and GCS remained significantly lower (all p < 0.05). The prevalence of subclinical systolic dysfunction was significantly higher in patients with ARPKD as compared with control subjects (33 vs. 0%; p < 0.001).

CONCLUSIONS

Children with ARPKD show significantly impaired cardiac phenotype, characterized by high rates of LV abnormal geometry paired with systolic mechanical dysfunction.

Clinical Usefulness of the Cardio-Ankle Vascular Index as a Predictor of Primary Cardiovascular Events in Patients With Chronic Kidney Disease

Background

The cardio-ankle vascular index (CAVI) is a physiologic marker reflecting arterial function. There have been no prospective studies investigating the relationship between CAVI and cardiovascular events in patients with chronic kidney disease (CKD). The aim of this prospective study was to assess the clinical usefulness of CAVI as a predictor of primary cardiovascular events in patients with CKD.

Methods

The study enrolled 460 outpatients with CKD but no history of cardiovascular disease (152 men and 308 women; mean ± standard deviation age, 74 ± 12 years). Patients were assigned to one of three groups: low (L, CAVI < 9; n = 100), medium (M, CAVI 9 - 10; n = 199), or high (H, CAVI > 10; n = 161). The utility of the CAVI as a predictor of primary cardiovascular events was evaluated.

Results

During the follow-up period (median 60.1 months), major adverse cardiovascular events (MACE) occurred in 91 cases (L, 8 (8.0%); M, 31 (15.6%); H, 52 (32.3%); P < 0.001, log-rank test). On multivariate Cox regression analysis, the risk for a MACE was significantly higher in group H than in non-group H (hazard ratio, 2.04; 95% confidence interval, 1.31 - 3.02; P < 0.01). A CAVI cut-off of 9.7 yielded the largest area under the curve, 0.701 (95% confidence interval: 0.657 - 0.743, P < 0.001), indicating a sensitivity of 74.0% and a specificity of 59.6% for discriminating between those who did and did not experience a MACE during follow-up.

Conclusions

The results of this study showed that a high CAVI is a predictor of primary cardiovascular events in patients with CKD.

Application of echocardiographic data in patients with chronic kidney disease

PURPOSE OF REVIEW

Patients with chronic kidney disease (CKD) are at a high risk for cardiovascular events and mortality, particularly heart failure. Echocardiography is the most commonly used diagnostic imaging modality for heart failure. The purpose of this review is to summarize recent literature that demonstrates how echocardiography may be used to define cardiac structure and function in the CKD population and to identify echocardiographic abnormalities that have utility in predicting clinical outcomes in this population.

RECENT FINDINGS

Recent studies have highlighted the high prevalence of echocardiographic abnormalities in this population, and the challenge of identifying specific echocardiographic criteria for heart failure. There have been advances in application of strain echocardiography for evaluating systolic function in patients with normal ejection fraction, understanding pulmonary hypertension and identifying echocardiographic correlates of albuminuria. Additional studies have focused on diastolic dysfunction, left ventricular hypertrophy and echocardiographic findings in children with CKD.

SUMMARY

Recent studies demonstrate the utility of echocardiography in characterizing heart structure and function and in providing potential tools for risk stratification in the high-risk CKD population.

Prevalence of left ventricular systolic dysfunction in pre-dialysis and dialysis patients with preserved left ventricular ejection fraction

AIMS

Patients with chronic kidney disease (CKD) have an excess of cardiovascular morbidity and mortality, with heart failure (HF) being particularly frequent. Reduced left ventricular ejection fraction (LVEF) defines left ventricular (LV) systolic dysfunction and is associated with poor prognosis. However, CKD patients may have HF symptoms with preserved LVEF. In this subgroup of patients, two-dimensional speckle tracking echocardiography can detect LV systolic dysfunction by analysing LV myocardial deformation. The present study evaluated the prevalence of impaired LV global longitudinal strain (GLS) in CKD patients with preserved LVEF and its prognostic consequences.

METHODS AND RESULTS

Overall, 200 pre-dialysis and dialysis patients (65% men, mean age 60 ± 14 years) with CKD stage 3b-5 and preserved LVEF (≥50%) were evaluated. Left ventricular systolic dysfunction despite preserved LVEF was defined by LV GLS ≤15.2% (cut-off value derived from two standard deviations below the mean value of individuals without structural heart disease). Impaired LV GLS (≤15.2%) despite preserved LVEF was observed in 32% of patients. During a median follow-up of 33 months (interquartile range 17-62 months), 47% of patients underwent renal transplantation, 9% were admitted with HF, and 28% died. Patients with LV GLS ≤15.2% showed significantly worse cumulative event-free survival rates of the combined endpoint of HF hospitalization and all-cause mortality compared to patients with LV GLS >15.2% (log-rank P = 0.018).

CONCLUSION

The prevalence of impaired LV GLS despite preserved LVEF in pre-dialysis and dialysis patients is relatively high. Patients with preserved LVEF but impaired LV GLS have an increased risk of HF hospitalization and all-cause mortality.

The importance of accurate measurement of aortic stiffness in patients with chronic kidney disease and end-stage renal disease

Cardiovascular (CV) disease is the leading cause of death in chronic kidney disease (CKD) and end-stage renal disease (ESRD). A key driver in this pathology is increased aortic stiffness, which is a strong, independent predictor of CV mortality in this population. Aortic stiffening is a potentially modifiable biomarker of CV dysfunction and in risk stratification for patients with CKD and ESRD. Previous work has suggested that therapeutic modification of aortic stiffness may ameliorate CV mortality. Nevertheless, future clinical implementation relies on the ability to accurately and reliably quantify stiffness in renal disease. Pulse wave velocity (PWV) is an indirect measure of stiffness and is the accepted standard for non-invasive assessment of aortic stiffness. It has typically been measured using techniques such as applanation tonometry, which is easy to use but hindered by issues such as the inability to visualize the aorta. Advances in cardiac magnetic resonance imaging now allow direct measurement of stiffness, using aortic distensibility, in addition to PWV. These techniques allow measurement of aortic stiffness locally and are obtainable as part of a comprehensive, multiparametric CV assessment. The evidence cannot yet provide a definitive answer regarding which technique or parameter can be considered superior. This review discusses the advantages and limitations of non-invasive methods that have been used to assess aortic stiffness, the key studies that have assessed aortic stiffness in patients with renal disease and why these tools should be standardized for use in clinical trial work.