Native T1 mapping: inter-study, inter-observer and inter-center reproducibility in hemodialysis patients

Background Native T1 mapping is a cardiovascular magnetic resonance (CMR) technique that associates with markers of fibrosis and strain in hemodialysis patients. The reproducibility of T1 mapping in hemodialysis patients, prone to changes in fluid status, is unknown. Accurate quantification of myocardial fibrosis in this population has prognostic potential. Methods Using 3 Tesla CMR, we report the results of 1) the inter-study, inter-observer and intra-observer reproducibility of native T1 mapping in 10 hemodialysis patients; 2) inter-study reproducibility of left ventricular (LV) structure and function in 10 hemodialysis patients; 3) the agreement of native T1 map and native T1 phantom analyses between two centres in 20 hemodialysis patients; 4) the effect of changes in markers of fluid status on native T1 values in 10 hemodialysis patients. Results Inter-study, inter-observer and intra-observer variability of native T1 mapping were excellent with co-efficients of variation (CoV) of 0.7, 0.3 and 0.4% respectively. Inter-study CoV for LV structure and function were: LV mass = 1%; ejection fraction = 1.1%; LV end-diastolic volume = 5.2%; LV end-systolic volume = 5.6%. Inter-centre variability of analysis techniques were excellent with CoV for basal and mid-native T1 slices between 0.8–1.2%. Phantom analyses showed comparable native T1 times between centres, despite different scanners and acquisition sequences (centre 1: 1192.7 ± 7.5 ms, centre 2: 1205.5 ± 5 ms). For the 10 patients who underwent inter-study testing, change in body weight (Δweight) between scans correlated with change in LV end-diastolic volume (ΔLVEDV) (r = 0.682;P = 0.03) representing altered fluid status between scans. There were no correlations between change in native T1 between scans (ΔT1) and ΔLVEDV or Δweight (P > 0.6). Linear regression confirmed ΔT1 was unaffected by ΔLVEDV or Δweight (P > 0.59). Conclusions Myocardial native T1 is reproducible in HD patients and unaffected by changes in fluid status at the levels we observed. Native T1 mapping is a potential imaging biomarker for myocardial fibrosis in patients with end-stage renal disease

The efficacy of prebiotic, probiotic and synbiotic supplementation in modulating gut-derived circulatory particles associated with cardiovascular disease in individuals receiving dialysis: a systematic review and meta-analysis of randomized controlled trials

ObjectiveThis systematic review and meta-analyses provide an up-to-date synthesis on the effects of supplementation on circulating levels of toxic metabolites, markers of uremia and inflammation, blood lipids, and other clinical outcomes.MethodsSeventeen databases were searched, supplemented with internet and hand searching. Randomized controlled trials of adult end-stage renal-disease individuals receiving either hemodialysis or peritoneal dialysis were eligible. Trials were restricted to those which had administered a prebiotic, probiotic, or synbiotic as an oral supplement. Primary outcomes were measures of circulating endotoxin, indoxyl-sulphate, and p-cresyl sulfate.ResultsTwenty-one trials were eligible (1152 randomized participants), of which 16 trials were considered to have a high risk of bias. The number of trials available for meta-analysis varied for each primary outcome. Synthesized data indicated that supplementation significantly reduced circulating levels of endotoxin (standardized mean difference, −0.61; 95% confidence interval, −1.03 to −0.20; P = .004; I2 = 0%), indoxyl-sulphate (−0.34; −0.64 to −0.04; P = .02; I2 = 0%), and p-cresyl sulfate (−0.34; −0.61 to −0.07; P = .01; I2 = 0%). For secondary outcomes, supplementation significantly reduced gastrointestinal symptoms (−0.54; −1.02 to −0.07; P = .02; I2 = 0%).ConclusionsSupplementation reduces toxic metabolites associated with cardiovascular disease and mortality in individuals receiving dialysis. However, the majority of trials included were low in quality.</p

Associations between physical activity levels and renal recovery following acute kidney injury stage 3: a feasibility study

Background: Acute kidney injury (AKI) can lead to chronic kidney disease, which results in poor long-term outcomes. There is plausibility that increased levels of physical activity may promote renal recovery post-AKI. This study aimed to investigate associations between physical activity levels and renal recovery following stage 3 AKI, and to assess the feasibility of measuring physical activity levels in this population.  Methods: Forty One hospitalised patients with AKI stage 3 were enrolled. Serum creatinine and estimated glomerular filtration rate (eGFR) were collected at 12 months prior to the development of AKI, during the hospital admission when the episode of AKI stage 3 occurred, and at 1-, 3- and 6-months post discharge. All participants completed the General Practice Activity Questionnaire (GPPAQ) to assess physical activity levels. A pedometer was also worn for 7 days immediately following discharge and at 6-months post discharge to ascertain an average daily step count. Feasibility outcomes including eligibility, recruitment and retention rates, and losses to follow up were also assessed.  Results: The average (± SD) baseline eGFR and median (IQR) serum creatinine was 71 ± 20 mL/min/1.73m2 and 85 (49) μmol/L respectively. A threefold increase in creatinine occurred during hospitalisation 436 (265) μmol/L. Greatest renal recovery occurred prior to discharge, with recovery continuing for a further three months. Inactive individuals (low GPPAQ scores) had consistently higher serum creatinine values compared to those who were active: 1 months 122 (111) μmol/L vs 70 (0) μmol/L, 6 months 112 (57) μmol/L vs 68 (0) μmol/L. Individuals with higher step counts also displayed better renal recovery 6-months post discharge (r = -0.600, p = 0.208).  Conclusions: Higher levels of physical activity are associated with improved renal recovery after 6- months following an episode of stage 3 AKI. A future randomised controlled trial is feasible and would be required to confirm these initial findings.</p

Novel cardiac nuclear magnetic resonance method for noninvasive assessment of myocardial fibrosis in hemodialysis patients.

Left ventricular hypertrophy and myocardial fibrosis frequently occur in patients with end-stage renal disease receiving hemodialysis therapy and are associated with poor prognosis. Native T1 mapping is a novel cardiac magnetic resonance imaging technique that measures native myocardial T1 relaxation, a surrogate of myocardial fibrosis. Here we compared global and segmental native myocardial T1 time and global longitudinal, circumferential and segmental strain, and cardiac function of 35 hemodialysis patients and 22 control individuals. The median native global T1 time was significantly higher in the hemodialysis than the control group (1270 vs. 1085 ms), with the septal regions of hemodialysis patients having significantly higher median T1 times than nonseptal regions (1293 vs. 1252 ms). The mean peak global circumferential strain and global longitudinal strain were both significantly reduced in hemodialysis patients compared with controls (-18.3 vs. -21.7 and -16.1 vs. -20.4, respectively). Systolic strain was also significantly reduced in the septum compared with the nonseptal myocardium in hemodialysis patients (-16.2 vs. -21.9) but not in control subjects. Global circumferential strain and longitudinal strain significantly correlated with global native T1 values (r = 0.41 and 0.55, respectively), and the septal native T1 significantly correlated with the septal systolic strain (r = 0.46). Thus, myocardial fibrosis may be assessed noninvasively with native T1 mapping; the interventricular septum appears to be particularly prone to the development of fibrosis in hemodialysis patients

Visual representation of reported effect direction of dietary and lifestyle mobile applications on participant reported outcomes.

Visual representation of reported effect direction of dietary and lifestyle mobile applications on participant reported outcomes.</p

Characteristics of included studies, process evaluations and developmental studies.

Characteristics of included studies, process evaluations and developmental studies.</p

Visual representation of reported effect direction of dietary and lifestyle mobile applications on clinical outcomes.

Visual representation of reported effect direction of dietary and lifestyle mobile applications on clinical outcomes.</p

Quality rating for the uncontrolled before-after studies.

Overall rating was rated as poor (0–4 as “yes”), fair (5–8 as “yes”), as good (9–12 as “yes”). A “fatal flaw” was defined as “no” for either questions 5 or 9.</p

Visual representation of reported effect direction of short messaging service (SMS) on participant reported outcomes.

Visual representation of reported effect direction of short messaging service (SMS) on participant reported outcomes.</p

Quality rating for the included randomised controlled trials & non-randomised controlled trials.

Overall quality rating was rated as poor (0–4 as “yes”), fair (5–10 as “yes”), as good (11–14 as “yes”). A “fatal flaw” defined as “no” for questions 7, 8, or 14 resulted in the study being downgraded a category (regardless of overall score).</p