Prognosis after aortic valve replacement in dialysis patients: results from the Swedish Renal Registry

Background

The choice of aortic valve prosthesis in aortic stenosis patients is based on patient preference, preoperative age, life expectancy, need for anticoagulant therapy and valve durability. Major uncertainties remain regarding optimal prosthetic valve choice in dialysis patients.

Objectives

The aim of the study was to compare the clinical outcomes after aortic valve replacement with mechanical (MAV) or bioprosthetic valves (BAV) in dialysis patients.

Methods

We used the observational, prospective, multicenter cohort from the Swedish Renal Registry, which includes all dialysis patients in Sweden. The study included 294 dialysis patients with aortic stenosis who underwent aortic valve replacement with MAV or BAV (obtained from surgical procedure codes) between 2005 and 2018, either before (n=155) or after dialysis start (n=139). Comorbidities and net adverse clinical events (bleeding events, stroke and reoperation) were obtained from national registries and defined by International Classification of Diseases codes (ICD-10). The incidence rate (IR) of primary endpoint comprised of all-cause death, bleeding events, stroke and aortic valve reoperation, as well as only all-cause death rates between recipients of MAV or BAV were estimated with Kaplan – Meier curves.

Results

The median age was 72 years (interquartile range [IQR]: 63.9, 77.3), 77% were males and 60% received mechanical valves. During a median follow-up of 1.49 years (IQR: 0.66–2.83), the primary endpoint occurred in 202 patients. Compared to BAV-recipients, those who received MAV had comparable IR of the primary end-point (40.1/100 person-years; [95% Confidence Interval (CI): 33.7–47.7], vs 36.2/100 person-years; [95% CI: 28.9–45.4], P=0.322) (Figure 1).

Mortality rate at 1-year of follow-up was 28.9% without difference between recipients of MAV or BAV (68.8% in MAV-group and 57.6% with BAV; mortality rate MAV 33.3/100 person-year; (95% CI: 27.9–39.8) vs BAV 27.3/100 person-year; (95% CI: 21.5–34.6), P=0. 183)), (Figure 2). Additional statistical analysis of the secondary endpoint based on the occurrence of aortic valve intervention before or after dialysis start, was consistent with the main results.

Conclusion

There is no difference in mortality and complication rates in dialysis patients who underwent aortic valve replacement with MAV or BAV.

Funding Acknowledgement

Type of funding sources: None.

Phenotypic features of vascular calcification in chronic kidney disease

BACKGROUND

Patients with chronic kidney disease stage 5 (CKD5) are predisposed to vascular calcification (VC), but the combined effect of factors associated with VC was sparsely investigated. We applied the relaxed linear separability (RLS) feature selection model to identify features that concomitantly associate with VC in CKD5 patients.

METHODS

Epigastric arteries collected during surgery from living donor kidney transplant recipients were examined to score the histological extent of medial VC. Sixty-two phenotypic features in 152 patients were entered into RLS model to differentiate between no-minimal VC (n = 93; score 0-1) and moderate-extensive VC (n = 59; score 2-3). The subset of features associated with VC was selected on the basis of cross-validation procedure. The strength of association of the selected features with VC was expressed by the absolute value of 'RLS factor'.

RESULTS

Among 62 features, a subset of 17 features provided optimal prediction of VC with 89% of patients correctly classified into their groups. The 17 features included traditional risk factors (diabetes, age, cholesterol, BMI and male sex) and markers of bone metabolism, endothelial function, metabolites, serum antibodies and mitochondrial-derived peptide. Positive RLS factors range from 1.26 to 4.05 indicating features associated with increased risk of VC, and negative RLS factors range from -0.95 to -1.83 indicating features associated with reduced risk of VC.

CONCLUSION

The RLS model identified 17 features including novel biomarkers and traditional risk factors that together concomitantly associated with medial VC. These results may inform further investigations of factors promoting VC in CKD5 patients.

Impact of inflammation on epigenetic DNA methylation - a novel risk factor for cardiovascular disease?

OBJECTIVE

The lifespan of dialysis patients is as short as in patients with metastatic cancer disease, mainly due to cardiovascular disease (CVD). DNA methylation is an important cellular mechanism modulating gene expression associated with ageing, inflammation and atherosclerotic processes.

DESIGN

DNA methylation was analysed in peripheral blood leucocytes from three different groups of chronic kidney disease (CKD) populations (37 CKD stages 3 and 4 patients, 98 CKD stage 5 patients and 20 prevalent haemodialysis patients). Thirty-six healthy subjects served as controls. Clinical characteristics (diabetes mellitus, nutritional status and presence of clinical CVD), inflammation and oxidative stress biomarkers, homocysteine and global DNA methylation in peripheral blood leucocytes (defined as HpaII/MspI ratio by the Luminometric Methylation Assay method) were evaluated. CKD stage 5 patients (n=98) starting dialysis treatment were followed for a period of 36 +/- 2 months.

RESULTS

Inflamed patients had lower ratios of HpaII/MspI, indicating global DNA hypermethylation. Analysis by the Cox regression model demonstrated that DNA hypermethylation (HpaII/MspI ratio <median) was significantly associated with both all-cause (RR 5.0; 95% CI: 1.7-14.8; P<0.01) and cardiovascular (RR 13.9; 95% CI: 1.8-109.3; P<0.05) mortality, even following the adjustment for age, CVD, diabetes mellitus and inflammation.

CONCLUSION

The present study demonstrates that global DNA hypermethylation is associated with inflammation and increased mortality in CKD.

Daily subcutaneous administration of recombinant human erythropoietin (rhEPO) in peritoneal dialysis patients: a European dose-response study

In a prospective randomized open multicenter study, 107 anemic (Hct < = 28%) peritoneal dialysis (PD) patients were treated with s.c. rhEPO daily. The mean observation period was 299 days (range 14-479 days). Patients were randomly assigned to 3 groups with different initial doses: 5 U/kg (G5), 10 U/kg (G10), 20 U/kg (G20). Initial doses were maintained for at least 8 weeks unless the target Hct (30-35%) was achieved earlier. The weekly increase of Hct was significantly (p < 0.05) dose-dependent: 0.19% in G5, 0.5% in G10 and 0.94% in G20. In case of insufficient response (< 0.5% per week), the dose was doubled every 4 weeks. Final doses on achieving the target Hct ranged from 5 to 40 U/kg (median 20 U/kg). The dose was then reduced to 50% and adjusted individually. The median maintenance dose was 9.9 U/kg/day. No tendency towards higher blood pressure or intensification of antihypertensive treatment was observed. When rhEPO is administered daily, 10 U/kg/day (70 U/kg weekly) is the recommended starting dose. The need for higher doses used in unsatisfactory response, should lead to further examination to rule out iron deficiency and other reasons for non-response. The median maintenance dose reported here is the lowest published in the literature for PD patients and seems to be linked to the daily injections.

Clostridium difficile-associated diarrhoea in uremic patients

An outbreak of 94 episodes of Clostridium difficile-associated diarrhoea in 62 patients in a nephrology ward over a two-year period was investigated. Quantitative stool cultures were performed on ten uremic patients not on antibiotics and without diarrhoea and on ten healthy controls. All diarrhoeal episodes were associated with Clostridium difficile, and no other bacterial pathogens were isolated. Thirty-two relapses occurred in 16 patients, fourteen of the relapses without preceding antibiotic exposure. Clostridium difficile could not be isolated from the environment of the patients. Uremic patients, who had a significantly increased number of Clostridium spp. in their stools, are predisposed to Clostridium difficile infections.