Association of hyponatraemia and renal function in type 1 cardiorenal syndrome

[Cardiorenal syndrome in geriatric patients]

The unfavorable mutual influence of the kidney and heart functions in acute or chronic kidney and/or heart failure has defined the cardiorenal syndrome (CRS) since a consensus conference in 2004. The pathophysiological considerations and the subsequent treatment approaches determine the classification into five types. The syndrome has a high prevalence in geriatric patients. The interactions of medications on one or the other organ system require an interaction of treatment modalities in order to improve the prognosis and prevent acute deterioration. Exact knowledge of the respective indications, differential treatment approaches and specifics in dealing with CRS can improve the current undertreatment due to concerns about side effects.

Impact of Dapagliflozin Treatment on Serum Sodium Concentrations in Acute Heart Failure

INTRODUCTION

The dynamics of serum sodium are important in acute heart failure (AHF), and hyponatremia is associated with a poor prognosis. The effect of sodium-glucose cotransporter type 2 inhibitors (SGLT2i) on serum sodium concentrations in AHF is unknown.

METHODS

In a single-centre, controlled, randomized study, patients were prescribed dapagliflozin in addition to standard treatment during the first 24 h of hospitalization versus standard treatments. The pre-specified outcome was an absolute change in plasma sodium concentrations between randomization (first 24 h after admission) and discharge. The secondary outcomes were an absolute change in serum sodium concentrations within 48 h of randomization and the persistence of hyponatremia.

RESULTS

The sample comprised 285 patients (53% males; average age 73.26 ± 13 years); 140 of these were randomized to the dapagliflozin group. The average ejection fraction was 46 ± 14%; 155 patients (54%) had ischaemic heart failure; and 35% had diabetes mellitus. Median N-terminal pro b-type natriuretic peptide was 4,225 [2,120; 9,105] pg/mL. The average estimated glomerular filtration rate was 53.9 ± 17.2 mL/min. Hospital mortality was 6.7%. At randomization, serum sodium concentrations were 139.8 ± 4.32 mmol/L in the dapagliflozin group versus 140.85 ± 4.04 mmol/L in the control group; p = 0.048. 48 h later, there was an increase in serum sodium in the dapagliflozin group (2 [-2; 4] mmol/L), as compared to the control group (-1 [-3.75; 2]); p < 0.001. This was accompanied by equilibration of the sodium levels between the groups (141.08 ± 4.08 mmol/L in the dapagliflozin group vs. 140.05 ± 4.82 mmol/L in the control group; p = 0.096). At the time of discharge, there was no difference in serum sodium concentrations (140.98 ± 4.77 mmol/L vs. 139.86 ± 4.45 mmol/L; p = 0.082). The increase in serum sodium concentrations during the period of observation [randomization; discharge] was small but statistically significant in the dapagliflozin group (1 [-3; 3.75] mmol/L vs. -2 [-4.5; 2] mmol/L; p = 0.015). Of 36 patients (21 in the dapagliflozin group and 15 in the control group) with baseline hyponatraemia, this persisted in 6 (16.6%) in the dapagliflozin group and in 11 (73.3%) in the control group (p = 0.008).

CONCLUSION

The use of dapagliflozin in AHF is associated with a tendency to the increase in serum sodium concentrations and lesser persistence of hyponatremia. This effect occurred within the first 48 h and persisted until discharge. The impact of dapagliflozin on serum sodium was more pronounced in patients with hyponatremia at randomization.

Potential Neuromodulation of the Cardio-Renal Syndrome

The cardio-renal syndrome (CRS) type 2 is defined as a progressive loss of renal function following a primary insult to the myocardium that may be either acute or chronic but is accompanied by a decline in myocardial pump performance. The treatment of patients with CRS is difficult, and the disease often progresses to end-stage renal disease that is refractory to conventional therapy. While a good deal of information is known concerning renal injury in the CRS, less is understood about how reflex control of renal sympathetic nerve activity affects this syndrome. In this review, we provide insight into the role of the renal nerves, both from the afferent or sensory side and from the efferent side, in mediating renal dysfunction in CRS. We discuss how interventions such as renal denervation and abrogation of systemic reflexes may be used to alleviate renal dysfunction in the setting of chronic heart failure. We specifically focus on a novel cardiac sensory reflex that is sensitized in heart failure and activates the sympathetic nervous system, especially outflow to the kidney. This so-called Cardiac Sympathetic Afferent Reflex (CSAR) can be ablated using the potent neurotoxin resinferitoxin due to the high expression of Transient Receptor Potential Vanilloid 1 (TRPV1) receptors. Following ablation of the CSAR, several markers of renal dysfunction are reversed in the post-myocardial infarction heart failure state. This review puts forth the novel idea of neuromodulation at the cardiac level in the treatment of CRS Type 2.