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Chronic kidney disease (CKD) is a complex condition with a prevalence of 10-15% worldwide. An inverse-graded relationship exists between cardiovascular events and mortality with kidney function which is independent of age, sex, and other risk factors. The proportion of deaths due to heart failure and sudden cardiac death increase with progression of chronic kidney disease with relatively fewer deaths from atheromatous, vasculo-occlusive processes. This phenomenon can largely be explained by the increased prevalence of CKD-associated cardiomyopathy with worsening kidney function. The key features of CKD-associated cardiomyopathy are increased left ventricular mass and left ventricular hypertrophy, diastolic and systolic left ventricular dysfunction, and profound cardiac fibrosis on histology. While these features have predominantly been described in patients with advanced kidney disease on dialysis treatment, patients with only mild to moderate renal impairment already exhibit structural and functional changes consistent with CKD-associated cardiomyopathy. In this review we discuss the key drivers of CKD-associated cardiomyopathy and the key role of hypertension in its pathogenesis. We also evaluate existing, as well as developing therapies in the treatment of CKD-associated cardiomyopathy., (© 2022. The Author(s).)

Chronic kidney disease is highly prevalent, affecting 10% to 15% of the adult population worldwide and is associated with increased cardiovascular morbidity and mortality. As chronic kidney disease worsens, a unique cardiovascular phenotype develops characterized by heart muscle disease, increased arterial stiffness, atherosclerosis, and hypertension. Cardiovascular risk is multifaceted, but most cardiovascular deaths in patients with advanced chronic kidney disease are caused by heart failure and sudden cardiac death. While the exact drivers of these deaths are unknown, they are believed to be caused by uremic cardiomyopathy: a specific pattern of myocardial hypertrophy, fibrosis, with both diastolic and systolic dysfunction. Although the pathogenesis of uremic cardiomyopathy is likely to be multifactorial, accumulating evidence suggests increased production of fibroblast growth factor-23 and αKlotho deficiency as potential major drivers of cardiac remodeling in patients with uremic cardiomyopathy. In this article we review the increasing understanding of the physiology and clinical aspects of uremic cardiomyopathy and the rapidly increasing knowledge of the biology of both fibroblast growth factor-23 and αKlotho. Finally, we discuss how dissection of these pathological processes is aiding the development of therapeutic options, including small molecules and antibodies, directly aimed at improving the cardiovascular outcomes of patients with chronic kidney disease and end-stage renal disease.

Increased native myocardial T1 times in chronic kidney disease (CKD) may be due to diffuse interstitial myocardial fibrosis (DIF) or due to interstitial edema/inflammation. Concerns relating to nephrogenic systemic fibrosis with gadolinium-based contrast agents (GBCA) limit their use in end-stage kidney disease (ESKD) to measure extracellular volume (ECV) and characterise myocardial fibrosis. This study aimed to examine stability of myocardial T1 and T2 times before, and within 2 months after kidney transplantation; a time frame when volume status normalises but myocardial remodelling is unlikely to have occurred, and to compare these with ECV using GBCA after transplantation. Twenty-four patients with ESKD underwent serial cardiovascular magnetic resonance imaging, including T1 and T2 mapping. GBCA was administered on follow-up provided eGFR was >30 ml/min/1.73 m 2 . Eighteen age- and sex-matched controls were studied at one timepoint. ECV (ECV 28 ± 2% vs. 24 ± 2%, p = 0.001) and T2 times were higher in ESKD compared to controls. After transplantation, septal T1 times increased (MOLLI 985 ms ± 25 vs. 1002 ms ± 30, p = 0.014; ShMOLLI 974 ms ± 39 vs. 992 ms ± 33, p = 0.113), LV volumes reduced (LVEDvol indexed 79 ± 24 vs. 63 ± 20 ml/m 2 , p = 0.005) but LV mass was unchanged (LV mass index 89 g/m 2  ± 38 to 83 g/m 2  ± 23, p = 0.141). T2 times did not change after transplantation. Both ECV and myocardial T1 times are elevated in ESKD, supporting the theory that elevated T1 times are due to DIF, although a contribution from myocardial edema cannot be fully excluded. The lack of any fall in T1 or T2 times after transplantation suggests that myocardial T1 times are a stable measure of DIF in CKD., (Copyright © 2019 The Authors. Published by Elsevier B.V. All rights reserved.)

The syndrome of uraemic cardiomyopathy, characterised by left ventricular hypertrophy, diffuse fibrosis and systolic and diastolic dysfunction, is common in chronic kidney disease and is associated with an increased risk of cardiovascular morbidity and mortality. The pathophysiological mechanisms leading to uraemic cardiomyopathy are not fully understood. We suggest that coronary microvascular dysfunction may be a key mediator in the development of uraemic cardiomyopathy, a phenomenon that is prevalent in other myocardial diseases that share phenotypical similarities with uraemic cardiomyopathy such as hypertrophic cardiomyopathy and heart failure with preserved ejection fraction. Here, we review the current understanding of uraemic cardiomyopathy, highlight different methods of assessing coronary microvascular function and evaluate the current evidence for coronary microvascular dysfunction in chronic kidney disease., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2019. Re-use permitted under CC BY. Published by BMJ.)

Patients with chronic kidney disease (CKD) have a disproportionately high risk of cardiovascular (CV) morbidity and mortality from the very early stages of CKD. This excess risk is believed to be the result of myocardial disease commonly termed uremic cardiomyopathy (UC). It has been suggested that interstitial myocardial fibrosis progresses with advancing kidney disease and may be the key mediator of UC. This longitudinal study reports data on the myocardial structure and function of 30 patients with CKD with no known cardiovascular disease and healthy controls. All patients underwent cardiac magnetic resonance imaging including T1 mapping and late gadolinium enhancement (if estimated glomerular filtration rate > 30 ml/min/1.73 m 2 ). Over a mean follow-up period of 2.7 ± 0.8 years, there was no change in left ventricular mass, volumes, ejection fraction, native myocardial T1 times, or extracellular volume with CKD or in healthy controls. Global longitudinal strain (20.6 ± 2.9 s -1 vs 19.8 ± 2.9 s -1 , p = 0.03) and mitral annular planar systolic excursion (13 ± 2 mm vs 12 ± 2 mm, p = 0.009) decreased in CKD but were clinically insignificant. Midwall late gadolinium enhancement was present in 4 patients at baseline and was unchanged at follow-up. Renal function was stable in this cohort over follow-up (change in estimated glomerular filtration rate was -3 ml/min/1.73 m 2 ) with no adverse clinical CV events. In conclusion, this study demonstrates that in a cohort of patients with stable CKD, left ventricular mass, native T1 times, and extracellular volume do not increase over a period of 2.7 years., (Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.)

Early-stage chronic kidney disease (CKD) is an under-recognized highly prevalent cardiovascular (CV) risk factor. Despite a clustering of conventional atherosclerotic risk factors, it is hypothesized that nonatherosclerotic processes, including left ventricular (LV) hypertrophy and fibrosis, account for a significant excess of CV risk. This cross-sectional observational study of 129 age- (mean age 57±10 years) and gender-matched subjects examined: nondiabetic CKD stages 2 to 4 (mean glomerular filtration rate 50±22 ml/min/1.73 m2) with no history of CV disease, subjects who are hypertensive with normal renal function, and healthy controls. Cardiac magnetic resonance imaging was performed for assessment of LV volumes and systolic function (myocardial deformation). Diffuse myocardial fibrosis was assessed using T1 mapping for native myocardial T1 times before contrast and myocardial extracellular volume (ECV) after gadolinium administration in combination with standard late gadolinium enhancement techniques for detection of coarse fibrosis. Patients with CKD had increased native T1 times (986±37 ms) and ECV (0.28±0.04) compared with controls (955±30 ms, 0.25±0.03) and subjects who are hypertensive (956±31 ms, 0.25±0.02, p<0.05). Both T1 times and ECV were correlated with impaired systolic function as assessed by global longitudinal systolic strain (r=-0.22, p<0.05, and r=-0.43, p<0.01, respectively). There were no differences in LV volumes, ejection fraction, or LV mass. T1 times and ECV did not correlate with conventional CV risk factors. In conclusion, diffuse myocardial fibrosis is increased in early CKD and is associated with abnormal global longitudinal strain, an early feature of uremic cardiomyopathy and a key indicator of adverse CV prognosis., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Chronic kidney disease (CKD) is an under-recognized, highly prevalent cardiovascular (CV) risk factor affecting 1 in 7 adults. Large epidemiological studies have clearly established a graded association between the severity of CKD and CV event rates. Although patients with end-stage renal disease who are undergoing dialysis are at greatest CV risk, the disease process is evident in the early stages of CKD with glomerular filtration rates as high as 75 ml/min/1.73 m(2). Indeed, these patients are at least 6 times more likely to die of CV disease than to reach end-stage CKD. Thus, the major impact of CKD on the population and the healthcare budget is not that of providing renal replacement therapy but the cost of death and disability from premature CV disease. Although end-stage CKD is characterized by a clustering of conventional atherosclerotic risk factors, it has little association with CV event rates. This is reflected in disproportionate levels of sudden cardiac death, heart failure, and stroke, rather than myocardial infarction. Thus it appears that nonatherosclerotic processes, including left ventricular hypertrophy and fibrosis, account for most of the excess CV risk. Over the past decade, the use of cardiac magnetic resonance in CKD has brought about an improved understanding of the adverse CV changes collectively known as uremic cardiomyopathy. The unique ability of cardiac magnetic resonance to provide a comprehensive noninvasive examination of cardiac structure and function, arterial function, myocardial tissue characterization (T1 mapping and inversion recovery imaging), and myocardial metabolic function (spectroscopy) is ideally suited to characterize the phenotype of CV disease in CKD and to provide insight into the mechanisms leading to uremic cardiomyopathy. Concerns relating to an association between gadolinium contrast agents and nephrogenic systemic fibrosis in dialysis recipients have led to the use of lower doses and lower-risk gadolinium agents that appear to minimize this risk., (Copyright © 2014 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: Abnormal left ventricular (LV) deformation is an independent predictor of poor cardiovascular outcome in end-stage renal disease. Studies in early-stage chronic kidney disease (CKD) have not been performed despite the known graded inverse relationship between glomerular filtration rate and adverse cardiovascular events., Methods: Forty patients with CKD stage 2 or 3 and no history of cardiovascular disease or diabetes and 30 healthy controls underwent Doppler myocardial imaging for longitudinal deformation (strain/strain rate)., Results: There were no differences in LV ejection fraction or systolic tissue Doppler velocities between patients with CKD and controls. In CKD, mean global strain (-15% +/- 4% vs -17% +/- 3%, P <.01) and mean global strain rate were reduced compared with controls (-0.88 +/- 0.16 vs -1.06 +/- 0.31, P <.05). Peak systolic strain was reduced in the basal lateral (-13.9% +/- 0.9% vs -17.9% +/- 1.02%, P <.01), basal septal (-17.1% +/- 0.8% vs -19.4% +/- 0.77%, P <.05), and mid-septal (-16.4% +/- 0.78% vs -18.9% +/- 0.88%, P <.05) walls with more basal postsystolic shortening (P <.01). Peak systolic strain rate was reduced in the basal lateral, mid-lateral, and mid-septal segments (P <.05)., Conclusion: Conventional measures of systolic function are preserved in early-stage CKD, but systolic deformation is abnormal, consistent with an adverse cardiovascular prognosis.