#91 Ultrafiltration rate induced cardiac strain (ULRICA) – study. Preliminary results of a prospective multicentre study in Sweden

Abstract Background and Aims Cardiovascular disease is the principal cause of mortality in the haemodialysis population, attributable not only to traditional risk factors but also to those specific to dialysis treatment such as fluid overload and ultrafiltration. These are modifiable risk factors. The cardiac biomarkers N-terminal pro-B-type natriuretic peptide (proBNP) and hs-Troponin T (TnT) increase during dialysis (Laveborn et al. 2012). Previous studies (Goto et al. 2023) hypothesize that this increase was related to ultrafiltration rate. The aim of the study was to determine if modifying ultrafiltration rate could reduce the elevation of these cardiac biomarkers. Method ULRICA is a multicentre study registered at ClinicalTrials.gov (NCT06153888), conducted in six centres across Sweden. It investigated the effect of ultrafiltration rate in adult, stable haemodialysis patients with a) interdialytic weight gain (IDWG) of more than 2.5% of dry body weight and b) an ultrafiltration rate of over 0.72 IDWG/h (standard UF rate). In a crossover setting each patient underwent one treatment according to standard prescription and, after one week, a second treatment with prolonged UF time to achieve an ultrafiltration rate of less than 0.6 IDWG/h or a reduction of ultrafiltration rate of at least 20% compared to standard treatment. All treatments were performed using low flux dialysers. Blood samples were collected before, after 180 min and after treatment. Levels of proBNP and TnT were then adjusted for haemoconcentration after the formula of Schneditz et al. (2012). Echocardiographic measurements were derived from echocardiographs performed within one year from study start under stable conditions. Due to the small sample size and non-normally distributed values, data were analysed using Wilcoxon signed-rank test for comparisons between treatments and Spearman's rank correlation coefficient for correlations. Results This preliminary one-centre report included 12 patients (four women, eight men) with a median age of 68.5 (range 32-86 years). There was a significant increase in TnT (p=0.008) and proBNP (p= 0.002) during dialysis with standard UF rate. The median levels of cardiac markers before treatment did not differ between the two treatments, TnT 61.5 ng/l (IQR 33.3-87.2) resp. 59.5 ng/l (IQR 35.5-90.0) and proBNP 12177.5 ng/l (IQR 3112.5-34773.0) resp. 9105 ng/l (IQR 2555.3-36803.0); (p=0.906 for TnT and p=0.638 for proBNP). The median increase of TnT was 4.1 ng/l (IQR 1.2-8.4) during standard treatment and 5.8 ng/l (IQR 0.1-10.3) during the prolonged treatment (p= 0.158). The median increase in proBNP was 3257.5 ng/l (IQR 855.0- 15074.7) during standard treatment and 2996.9 ng/l (IQR 724.1-13338.4) during the prolonged treatment (p=0.814). The changes at 180 min were also non-significant (p=0.182 for TnT and p=0.875 for proBNP). There was a positive correlation between the change in proBNP during treatment and age (R=0.85, p<0.001) and left ventricular mass index (LVMI) (R=0.89, p=0.019). There was also a correlation between age and LVMI (R=0.83, p=0.042). Conclusion Preliminary data of a small group of patients confirm an increase of TnT and proBNP during dialysis. Age and LVMI are strongly associated with increase of proBNP. To show whether a reduction of ultrafiltration rate per se might reduce the release of cardiac biomarkers during haemodialysis treatment, further inclusion of patients is in progress.