Myocardial characterization in pre-dialysis chronic kidney disease: a study of prevalence, patterns and outcomes.

BACKGROUND: Late gadolinium enhancement (LGE) using cardiac magnetic resonance (CMR) characterizes myocardial disease and predicts an adverse cardiovascular (CV) prognosis. Myocardial abnormalities, are present in early chronic kidney disease (CKD). To date there are no data defining prevalence, pattern and clinical implications of LGE-CMR in CKD. METHODS: Patients with pre-dialysis CKD (stage 2-5) attending specialist renal clinics at University Hospital Birmingham (UK) who underwent gadolinium enhanced CMR (1.5 T) between 2005 and 2017 were included. The patterns and presence (LGEpos) / absence (LGEneg) of LGE were assessed by two blinded observers. Association between LGE and CV outcomes were assessed. RESULTS: In total, 159 patients received gadolinium (male 61%, mean age 55 years, mean left ventricular ejection fraction 69%, left ventricular hypertrophy 5%) with a median follow up period of 3.8 years [1.04-11.59]. LGEpos was present in 55 (34%) subjects; the patterns were: right ventricular insertion point n = 28 (51%), mid wall n = 18 (33%), sub-endocardial n = 5 (9%) and sub-epicardial n = 4 (7%). There were no differences in left ventricular structural or functional parameters with LGEpos. There were 12 adverse CV outcomes over follow up; 7 of 55 with LGEpos and 5 of 104 LGEneg. LGEpos was not predicted by age, gender, glomerular filtration rate or electrocardiographic abnormalities. CONCLUSIONS: In a selected cohort of subjects with moderate CKD but low CV risk, LGE was present in approximately a third of patients. LGE was not associated with adverse CV outcomes. Further studies in high risk CKD cohorts are required to assess the role of LGE with multiplicative risk factors.

A randomized, multicenter, open-label, blinded end point trial comparing the effects of spironolactone to chlorthalidone on left ventricular mass in patients with early-stage chronic kidney disease: Rationale and design of the SPIRO-CKD trial.

BACKGROUND: Chronic kidney disease (CKD) is associated with increased left ventricular (LV) mass and arterial stiffness. In a previous trial, spironolactone improved these end points compared with placebo in subjects with early-stage CKD, but it is not known whether these effects were specific to the drug or secondary to blood pressure lowering. AIM: The aim was to investigate the hypothesis that spironolactone is superior to chlorthalidone in the reduction of LV mass while exerting similar effects on blood pressure. DESIGN: This is a multicenter, prospective, randomized, open-label, blinded end point clinical trial initially designed to compare the effects of 40weeks of treatment with spironolactone 25mg once daily to chlorthalidone 25mg once daily on the co-primary end points of change in pulse wave velocity and change in LV mass in 350 patients with stages 2 and 3 CKD on established treatment with an angiotensin-converting enzyme inhibitor or an angiotensin receptor blocker. Because of slow recruitment rates, it became apparent that it would not be possible to recruit this sample size within the funded time period. The study design was therefore changed to one with a single primary end point of LV mass requiring 150 patients. Recruitment was completed on 31 December 2016, at which time 154 patients had been recruited. Investigations included cardiac magnetic resonance imaging, applanation tonometry, 24-hour ambulatory blood pressure monitoring, and laboratory tests. Subjects are assessed before and after 40weeks of randomly allocated drug therapy and at 46weeks after discontinuation of the study drug.

Infection-related mortality is higher for kidney allograft recipients with pretransplant diabetes mellitus.

AIMS/HYPOTHESIS: The risk of infection-related mortality in kidney allograft recipients with pre-existing diabetes mellitus is unknown. We determined the risk of infection-related mortality after kidney transplantation in a population-based cohort stratified by diagnosis of pre-existing diabetes mellitus. METHODS: We linked data between two national registries (Hospital Episode Statistics and the Office for National Statistics) to select all mortality events after kidney transplantation in England between April 2001 and March 2012. The primary outcome measure was infection-related mortality after transplantation comparing diabetic with non-diabetic recipients. RESULTS: A total of 19,103 kidney allograft recipients were analysed; 2,968 (15.5%) were known to have diabetes before kidney transplantation. After transplantation, 2,085 deaths (10.9%) occurred (median follow-up 4.4 years [interquartile range 2.2-7.3]), with 434 classified as secondary to infection (20.8% of all deaths). Risk of overall (16.0% vs 10.0%, p < 0.001) and infection-related (3.3% vs 2.1%, p < 0.001) mortality after kidney transplantation was higher for diabetic than non-diabetic recipients, respectively. No cytomegalovirus-related deaths occurred in diabetic recipients compared with 5.7% in non-diabetic recipients (p < 0.007), with a trend towards more unspecified sepsis in diabetic recipients (30.6% vs 22.6%, respectively, p = 0.070). Diabetes at the time of transplantation was an independent risk factor predicting infection-related mortality in kidney allograft recipients after transplantation (HR 1.71 [95% CI 1.36, 2.15], p < 0.001). CONCLUSIONS/INTERPRETATION: Infection-related mortality is more common in kidney allograft recipients with pre-existing diabetes mellitus. Further work is required to determine whether attenuated immunosuppression is beneficial for diabetic kidney allograft recipients.

Cardiovascular Effects of Unilateral Nephrectomy in Living Kidney Donors at 5 Years.

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Defining Myocardial Abnormalities Across the Stages of Chronic Kidney Disease: A Cardiac Magnetic Resonance Imaging Study.

OBJECTIVES: A proof of concept cross-sectional study investigating changes in myocardial abnormalities across stages of chronic kidney disease (CKD). Characterizing noninvasive markers of myocardial fibrosis on cardiac magnetic resonance, echocardiography, and correlating with biomarkers of fibrosis, myocardial injury, and functional correlates including exercise tolerance. BACKGROUND: CKD is associated with an increased risk of cardiovascular death. Much of the excess mortality is attributed to uremic cardiomyopathy, defined by increased left ventricular hypertrophy, myocardial dysfunction, and fibrosis. The prevalence of these abnormalities across stages of CKD and their impact on cardiovascular performance is unknown. METHODS: A total of 134 nondiabetic, pre-dialysis subjects with CKD stages 2 to 5 without myocardial ischemia underwent cardiac magnetic resonance (1.5-T) including; T1 mapping (biomarker of diffuse fibrosis), T2 mapping (edema), late gadolinium enhancement, and assessment of aortic distensibility. Serum biomarkers including collagen turnover (P1NP, P3NP), troponin T, and N-terminal pro-B-type natriuretic peptide were measured. Cardiovascular performance was quantified by bicycle cardiopulmonary exercise testing and echocardiography. RESULTS: Native myocardial T1 times increased incrementally from stage 2 to 5 (966 ± 21 ms vs. 994 ± 33 ms; p < 0.001), independent of hypertension and aortic distensibility. Left atrial volume, E/e', N-terminal pro-B-type natriuretic peptide, P1NP, and P3NP increased with CKD stage (p < 0.05), while effort tolerance (% predicted VO2Peak, %VO2VT) decreased (p < 0.001). In multivariable linear regression models, estimated glomerular filtration rate was the strongest predictor of native myocardial T1 time (p < 0.001). Native myocardial T1 time, left atrial dilatation, and high-sensitivity troponin T were independent predictors of % predicted VO2Peak (p < 0.001). CONCLUSIONS: Imaging and serum biomarkers of myocardial fibrosis increase with advancing CKD independent of effects of left ventricular afterload and might be a key intermediary in the development of uremic cardiomyopathy. Further studies are needed to determine whether these changes lead to the increased rates of heart failure and death in CKD. (Left Ventricular Fibrosis in Chronic Kidney Disease [FibroCKD]; NCT03176862).

Changes in Blood Pressure and Arterial Hemodynamics following Living Kidney Donation.

BACKGROUND AND OBJECTIVES: The Effect of a Reduction in GFR after Nephrectomy on Arterial Stiffness and Central Hemodynamics (EARNEST) study was a multicenter, prospective, controlled study designed to investigate the associations of an isolated reduction in kidney function on BP and arterial hemodynamics. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Prospective living kidney donors and healthy controls who fulfilled criteria for donation were recruited from centers with expertise in vascular research. Participants underwent office and ambulatory BP measurement, assessment of arterial stiffness, and biochemical tests at baseline and 12 months. RESULTS: A total of 469 participants were recruited, and 306 (168 donors and 138 controls) were followed up at 12 months. In the donor group, mean eGFR was 27 ml/min per 1.73 m2 lower than baseline at 12 months. Compared with baseline, at 12 months the mean within-group difference in ambulatory day systolic BP in donors was 0.1 mm Hg (95% confidence interval, -1.7 to 1.9) and 0.6 mm Hg (95% confidence interval, -0.7 to 2.0) in controls. The between-group difference was -0.5 mm Hg (95% confidence interval, -2.8 to 1.7; P=0.62). The mean within-group difference in pulse wave velocity in donors was 0.3 m/s (95% confidence interval, 0.1 to 0.4) and 0.2 m/s (95% confidence interval, -0.0 to 0.4) in controls. The between-group difference was 0.1 m/s (95% confidence interval, -0.2 to 0.3; P=0.49). CONCLUSIONS: Changes in ambulatory peripheral BP and pulse wave velocity in kidney donors at 12 months after nephrectomy were small and not different from controls. CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER: NCT01769924 (https://clinicaltrials.gov/ct2/show/NCT01769924).

Early effects of kidney transplantation on the heart - A cardiac magnetic resonance multi-parametric study.

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 m2. Eighteen age- and sex-matched controls were studied at one timepoint. ECV (ECV 28 ±â€¯2% vs. 24 ±â€¯2%, p = 0.001) and T2 times were higher in ESKD compared to controls. After transplantation, septal T1 times increased (MOLLI 985 ms ±â€¯25 vs. 1002 ms ±â€¯30, p = 0.014; ShMOLLI 974 ms ±â€¯39 vs. 992 ms ±â€¯33, p = 0.113), LV volumes reduced (LVEDvol indexed 79 ±â€¯24 vs. 63 ±â€¯20 ml/m2, p = 0.005) but LV mass was unchanged (LV mass index 89 g/m2 ±â€¯38 to 83 g/m2 ±â€¯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.

Reference ranges for three-dimensional feature tracking cardiac magnetic resonance: comparison with two-dimensional methodology and relevance of age and gender.

Myocardial deformation is a sensitive marker of sub-clinical myocardial dysfunction that carries independent prognostic significance across a broad range of cardiovascular diseases. It is now possible to perform 3D feature tracking of SSFP cines on cardiac magnetic resonance imaging (FT-CMR). This study provides reference ranges for 3D FT-CMR and assesses its reproducibility compared to 2D FT-CMR. One hundred healthy individuals with 10 men and women in each of 5 age deciles from 20 to 70 years, underwent 2D and 3D FT-CMR of left ventricular myocardial strain and strain rate using SSFP cines. Good health was defined by the absence of hypertension, diabetes, obesity, dyslipidaemia, or any cardiovascular, renal, hepatic, haematological and systemic inflammatory disease. Normal values for myocardial strain assessed by 3D FT-CMR were consistently lower compared with 2D FT-CMR measures [global circumferential strain (GCS) 3D - 17.6 ± 2.6% vs. 2D - 20.9 ± 3.7%, P < 0.005]. Validity of 3D FT-CMR was confirmed against other markers of systolic function. The 3D algorithm improved reproducibility compared to 2D, with GCS having the best inter-observer agreement [intra-class correlation (ICC) 0.88], followed by global radial strain (GRS; ICC 0.79) and global longitudinal strain (GLS, ICC 0.74). On linear regression analyses, increasing age was weakly associated with increased GCS (R2 = 0.15, R = 0.38), peak systolic strain rate, peak late diastolic strain rate, and lower peak early systolic strain rate. 3D FT-CMR offers superior reproducibility compared to 2D FT-CMR, with circumferential strain and strain rates offering excellent intra- and inter-observer variability. Normal range values for myocardial strain measurements using 3D FT-CMR are provided.

Chronic kidney disease as a cardiovascular risk factor: lessons from kidney donors.

Chronic kidney disease (CKD) is a major risk factor for cardiovascular disease but is often associated with other risks such as diabetes and hypertension and can be both a cause and an effect of cardiovascular disease. Although epidemiologic data of an independent association of reduced glomerular filtration rate with cardiovascular risk are strong, causative mechanisms are unclear. Living kidney donors provide a useful model for assessing the "pure" effects of reduced kidney function on the cardiovascular system. After nephrectomy, the glomerular filtration rate ultimately falls by about one-third so many can be classified as having chronic kidney disease stages 2 or 3. This prompts concern based on the data showing an elevated cardiovascular risk with these stages of chronic kidney disease. However, initial data suggested no increase in adverse cardiovascular effects compared with control populations. Recent reports have shown a possible late increase in cardiovascular event rates and an early increase in left ventricular mass and markers of risk such as urate and albuminuria. The long-term significance of these small changes is unknown. More detailed and long-term research is needed to determine the natural history of these changes and their clinical significance.

Diffuse interstitial fibrosis and myocardial dysfunction in early chronic kidney disease.

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.