Proposal for heart failure progression based on the 'chloride theory': worsening heart failure with increased vs. non-increased serum chloride concentration

Risk factors for cardio-cerebrovascular events among patients undergoing continuous ambulatory peritoneal dialysis and their association with serum magnesium

Serum magnesium levels exceeding 0.9 mmol/L are associated with increased survival rates in patients with CKD. This retrospective study aimed to identify risk factors for cardio-cerebrovascular events among patients receiving continuous ambulatory peritoneal dialysis (CAPD) and to examine their correlations with serum magnesium levels. Sociodemographic data, clinical physiological and biochemical indexes, and cardio-cerebrovascular event data were collected from 189 patients undergoing CAPD. Risk factors associated with cardio-cerebrovascular events were identified by univariate binary logistic regression analysis. Correlations between the risk factors and serum magnesium levels were determined by correlation analysis. Univariate regression analysis identified age, C-reactive protein (CRP), red cell volume distribution width standard deviation, red cell volume distribution width corpuscular volume, serum albumin, serum potassium, serum sodium, serum chlorine, serum magnesium, and serum uric acid as risk factors for cardio-cerebrovascular events. Among them, serum magnesium ≤0.8 mmol/L had the highest odds ratio (3.996). Multivariate regression analysis revealed that serum magnesium was an independent risk factor, while serum UA (<440 μmol/L) was an independent protective factor for cardio-cerebrovascular events. The incidence of cardio-cerebrovascular events differed significantly among patients with different grades of serum magnesium (χ2 = 12.023, p = 0.002), with the highest incidence observed in patients with a serum magnesium concentration <0.8 mmol/L. High serum magnesium levels were correlated with high levels of serum albumin (r = 0.399, p < 0.001), serum potassium (r = 0.423, p < 0.001), and serum uric acid (r = 0.411, p < 0.001), and low levels of CRP (r = -0.279, p < 0.001). In conclusion, low serum magnesium may predict cardio-cerebrovascular events in patients receiving CAPD.

Acetazolamide Tolerance in Acute Decompensated Heart Failure: An Observational Study

Objectives: This real-life study aimed to evaluate the safety of acetazolamide (ACZ), a carbonic anhydrase inhibitor with diuretic effects. ACZ has recently been proven to improve decongestion in the context of patients hospitalized for acute heart failure (HF). However, data in terms of safety are lacking. Methods: We conducted a monocentric observational prospective study from November 2023 to February 2024 in a 12-bed cardiology department, recording adverse events (hypotension, severe metabolic acidosis, severe hypokalemia and renal events) during in-hospital HF treatment. All patients hospitalized for acute HF during the study period treated with ACZ (500 mg IV daily for 3 days) on top of IV furosemide (n = 28, 48.3%) were compared with patients who have been treated with IV furosemide alone (n = 30, 51.7%). Results: The patients treated with ACZ were younger than those without (median age 78 (range 67-86) vs. 85 (79-90) years, respectively, p = 0.01) and had less frequent chronic kidney disease (median estimated glomerular fraction rate (60 (35-65) vs. 38 (26-63) mL/min, p = 0.02). As concerned adverse events during HF treatment, there were no differences in the occurrences of hypotension (three patients [10.7%] in the ACZ group vs. four [13.3%], p = 0.8), renal events (four patients [14.3%] in the ACZ group vs. five [16.7%], p = 1) and severe hypokalemia (two [7.1%] in the ACZ group vs. three [10%], p = 1). No severe metabolic acidosis occurred in either group. Conclusions: Although the clinical characteristics differed at baseline, with younger age and better renal function in patients receiving ACZ, the tolerance profile did not significantly differ from patients receiving furosemide alone. Additional observational data are needed to further assess the safety of ACZ-furosemide combination in the in-hospital management of HF, especially in older, frail populations.

Impact of hypochloremia as a prognostic factor in patients with heart failure, a retrospective cohort study

BACKGROUND

some studies suggest that hypochloremia is a risk factor in the prognosis of heart failure (HF) in patients with recent decompensation.

MATERIALS AND METHODS

retrospective cohort study of patients discharged due to HF decompensation who began follow-up in a specialized clinic. Two groups are defined: patients with hypochloremia (chloride < 98 mmol/L) and normochloremic patients (chloride > 98 mmol/L) in the initial assessment within the first month after discharge. The rate of intravenous diuretic rescue, emergency department visits, readmission for HF and cardiovascular (CV) death are compared using a Cox proportional hazards model.

RESULTS

165 patients were included (59% women, mean age 85 years), with 60 (36%) having hypochloremia. Both groups were comparable in terms of baseline characteristics, except for female sex, presence of peripheral artery disease, moderate-to-severe liver disease (more prevalent in the hypochloremia group), PROFUND index, and baseline furosemide dose (higher in patients with hypochloremia). The incidence of the primary event was higher in subjects with hypochloremia than in normochloremic subjects (HR: 1.59, 95% CI 0.97-2.62), mainly due to the need for intravenous diuretic rescue (HR: 1.86, 95% CI 1.07-3.24).

CONCLUSIONS

hypochloremia following admission for HF decompensation is associated with a greater need for intravenous diuretic rescue therapy and probably worse overall prognosis across the spectrum of the disease, regardless of left ventricular ejection fraction (LVEF).

Positive association between sodium-to-chloride ratio and in-hospital mortality of acute heart failure

Previous studies have suggested that levels of sodium and chloride in the blood may be indicative of the prognosis of different medical conditions. Nevertheless, the assessment of the prognostic significance of the sodium-to-chloride (Na/Cl) ratio in relation to in-hospital mortality among individuals suffering from acute heart failure (AHF) remains unexplored. In this study, the participants were selected from the Medical Information Mart for Intensive Care IV database and divided into three groups based on the Na/Cl ratio level upon admission. The primary results were the mortality rate within the hospital. Cox regression, Kaplan-Meier curves, receiver operator characteristic (ROC) curve analysis and subgroup analyses were utilized to investigate the correlation between the admission Na/Cl ratio and outcomes in critically ill patients with AHF. A total of 7844 patients who met the selection criteria were included in this study. After adjusting for confounders, the multivariable Cox regression analysis revealed that the baseline Na/Cl ratio significantly elevated the risk of in-hospital mortality among critically ill patients with AHF (HR = 1.34, 95% CI 1.21-1.49). Furthermore, when the Na/Cl ratio was converted into a categorical factor and the initial tertile was taken as a point of comparison, the hazard ratios (HRs) and 95% confidence intervals (CIs) for the second and third tertiles were 1.27 (1.05-1.54) and 1.53 (1.27-1.84), respectively. Additionally, a P value indicating a significant trend of < 0.001 was observed. ROC curve analysis showed that Na/Cl ratio had a more sensitive prognostic value in predicting in-hospital mortality of AHF than the sodium or chloride level alone (0.564 vs. 0.505, 0.544). Subgroup examinations indicated that the association between the Na/Cl ratio upon admission and the mortality rate of critically ill patients with AHF remained consistent in the subgroups of hyponatremia and hypochlorhydria (P for interaction > 0.05). The linear relationship between the Na/Cl ratio and in-hospital mortality in AHF patients indicates a positive association.

The association between serum chloride and mortality in ICU patients with heart failure: The impact of bicarbonate

OBJECTIVE

To assess whether serum chloride predicts risk of death in intensive care unit (ICU) patients with heart failure (HF) and the effect of bicarbonate on the efficacy of serum chloride in predicting risk of death in ICU patients.

METHODS

A total of 9364 HF patients hospitalized in the ICU were enrolled. Patients were divided into hypochloremia (< 96 mEq/L), normal chloride (96-108 mEq/L), and hyperchloremia (> 108 mEq/L) groups. Similarly, we divided the serum bicarbonate level into three groups: low bicarbonate (< 22 mEq/L), medium bicarbonate (22-26 mEq/L), and high bicarbonate (> 26 mEq/L). The outcome of this study was in-hospital mortality. Then, we analyzed the association between abnormal serum chloride and mortality according to the category of serum bicarbonate and assessed the interaction effect. Restricted cubic spline (RCS) was used to show possible nonlinear associations.

RESULTS

In the overall study population, hypochloremia was associated with a higher risk of in-hospital mortality than normal chloride (odds ratio [OR] 1.54, 95% confidence interval [CI] 1.26-1.86, P < 0.001), hyperchloremia was not significantly related to in-hospital mortality (OR 1.00, 95% CI 0.85-1.19, P = 0.962). However, a linear association between serum chloride and in-hospital mortality was found in the low and normal bicarbonate groups (all P for nonlinear >0.05).

CONCLUSIONS

Hypochloremia is associated with in-hospital mortality and longer hospital stay in critically ill patients with HF. In addition, risk of death in the low and medium serum bicarbonate groups decreased with increasing serum chloride level.

Serum Chloride and Heart Failure

Despite significant advances in management, heart failure continues to impose a significant epidemiologic burden with high prevalence and mortality rates. For decades, sodium has been the serum electrolyte most commonly associated with outcomes; however, challenging the conventional paradigm of sodium's influence, recent studies have identified a more prominent role in serum chloride in the pathophysiology of heart failure. More specifically, hypochloremia is associated with neurohumoral activation, diuretic resistance, and a worse prognosis in patients with heart failure. This review examines basic science, translational research, and clinical studies to better characterize the role of chloride in patients with heart failure and additionally discusses potential new therapies targeting chloride homeostasis that may impact the future of heart failure care.

The Prognostic Role of Spot Urinary Sodium and Chloride in a Cohort of Hospitalized Advanced Heart Failure Patients: A Pilot Study

Recent studies have demonstrated the prognostic value of spot urinary sodium (UNa+) in acutely decompensated chronic HF (ADCHF) patients. However, data on the prognostic role of UNa+ and spot urinary chloride (UCl-) in patients with advanced HF are limited. In the present prospective pilot study, we examined the predictive value of UNa+ and UCl- concentration at baseline, at 2 h and at 24 h after admission for all-cause mortality and HF rehospitalization up to 3 months post-discharge. Consecutive advanced HF patients (n = 30) admitted with ADCHF and aged > 18 years were included in the study. Loop diuretics were administered based on the natriuresis-guided algorithm recommended by the recent HF guidelines. Exclusion criteria were cardiogenic shock, acute coronary syndrome, estimated glomerular filtration rate < 15 mL/min/1.73 m2, severe hepatic dysfunction (Child-Pugh category C), and sepsis. UNa+ at baseline (Area Under the Curve (AUC) = 0.75, 95% Confidence Interval (CI) (0.58-0.93), p = 0.019) and at 2 h after admission (AUC = 0.80, 95% CI: 0.64-0.96, p = 0.005) showed good and excellent discrimination, respectively. UCl- at 2 h after admission (AUC = 0.75, 95%CI (0.57-0.93), p = 0.017) demonstrated good discrimination. In the multivariate logistic regression analysis, UNa+ at 2 h (p = 0.02) and dose of loop diuretics at admission (p = 0.03) were the only factors independently associated with the study outcome. In conclusion, UNa+ and UCl- may have a prognostic role in hospitalized advanced HF patients.

Relationship between serum chloride and prognosis in non-ischaemic dilated cardiomyopathy: a large retrospective cohort study

OBJECTIVES

Serum chloride has a unique homeostatic role in modulating neurohormonal pathways. Some studies have reported that hypochloremia has potential prognostic value in cardiovascular diseases; thus, we aimed to investigate the association of baseline serum chloride with clinical outcomes in elderly patients with non-ischaemic dilated cardiomyopathy (NIDCM).

DESIGN

Retrospective study.

SETTING AND PARTICIPANT

A total of 1088 patients (age ≥60 years) diagnosed with NIDCM were enrolled from January 2010 to December 2019.

RESULTS

Logistic regression analyses showed that serum chloride was significantly associated with in-hospital death. Receiver operating characteristic (ROC) curve analyses showed that serum chloride had excellent prognostic ability for in-hospital and long-term death (area under the curve (AUC)=0.690 and AUC=0.710, respectively). Kaplan-Meier survival analysis showed that the patients with hypochloremia had worse prognoses than those without hypochloremia (log-rank χ²=56.69, p<0.001). After adjusting for age, serum calcium, serum sodium, left ventricular ejection fraction, lg NT-proBNP and use of diuretics, serum chloride remained an independent predictor of long-term death (HR 0.934, 95% CI 0.913 to 0.954, p<0.001).

CONCLUSIONS

Serum chloride concentration was a prognostic indicator in elderly patients with NIDCM, and hypochloremia was significantly associated with both in-hospital and long-term poor outcomes.

Mechanistic insights into chloride-related heart failure progression according to the plasma volume status

Aims

Two types of heart failure (HF) progression were recently proposed on the basis of an increased vs. non‐increased serum chloride concentration. The applicability of this concept to real‐world HF pathophysiology requires further investigation. The present study evaluated the mechanisms of HF progression to a different type according to changes in the estimated plasma volume status (ePVS).

Methods and results

Data from 47 patients (32% men; 78.2 ± 9.7 years of age) with stable to worsening HF (37.5 ± 16 days) were analysed. Physical examination, standard blood tests, and b‐type natriuretic peptide (BNP) measurements were conducted. The ePVS was calculated as follows: ePVS (dL/g) = [100 − haematocrit (%)]/[haemoglobin (g/dL)]. For the study subjects as a whole (n = 47), changes in the ePVS correlated positively with changes in the serum chloride concentration from stable to worsening HF (r = 0.398, P = 0.0056). When divided into two groups of worsening HF with an increased (n = 31) vs. non‐increased serum chloride concentration (n = 16), no significant baseline differences in body weight, serum logBNP, or ePVS were detected between groups. Under worsening HF, the increase in body weight (2.34 ± 1.12 vs. 2.59 ± 1.56 kg, P = 0.57) and logBNP (0.39 ± 0.30 vs. 0.54 ± 0.31 pg/mL, P = 0.13) did not differ between groups, but the increase in the ePVS was smaller in the group with a non‐increased serum chloride concentration compared with that with an increased serum chloride concentration (0.292 ± 0.49 vs. 0.653 ± 0.60 dL/g, P = 0.044). An increase in the %change in ePVS ≥ 10% was less common in patients with a non‐increased chloride concentration (37% vs. 71%, P = 0.03). Patients with a non‐increased serum chloride concentration had more HF signs (3.31 ± 0.79 vs. 2.65 ± 0.71, P = 0.005) and a higher incidence of pulmonary rales (63% vs. 16%, P = 0.0024) than those with an increased serum chloride concentration.

Conclusions

According to the changes in the ePVS, HF progression may result from a difference between two HF types (i.e. increased vs. non‐increased serum chloride concentration) in the cardiac reserve in response to a given cardiac burden by modulating plasma volume status via the possible tonicity potential of chloride.

Fluid and Salt Balance and the Role of Nutrition in Heart Failure

The main challenges in heart failure (HF) treatment are to manage patients with refractory acute decompensated HF and to stabilize the clinical status of a patient with chronic heart failure. Beyond the use of medications targeted in the inhibition of the neurohormonal system, the balance of salt and fluid plays an important role in the maintenance of clinical compensation in respect of renal function. In the case of heart failure, a debate of opinion exists on salt restriction. Restricted dietary sodium might lead to worse outcomes in heart failure patients due to the activation of the neurohormonal system and malnutrition. On the contrary, positive sodium balance is the primary driver of water retention and, ultimately, volume overload in acute HF. Some recent studies reported associations of decreased salt consumption with higher readmission rates and increased mortality. Thus, the usefulness of salt restriction in heart failure management remains debated. The use of individualized nutritional support, compared with standard hospital food, was effective in reducing these risks, particularly in the group of patients at high nutritional risk.

Prognostic significance of serum chloride level in heart failure patients with preserved ejection fraction

Aims

The prognostic value of serum chloride level has been reported primarily in patients with heart failure with reduced ejection fraction, and hence, there is limited evidence in patients of heart failure with preserved ejection fraction (HFpEF). This study was conducted to clarify the relationship between serum chloride level and clinical outcomes in patients with HFpEF with acute decompensated heart failure (ADHF).

Methods and results

Patient data were extracted from The Prospective mUlticenteR obServational stUdy of patIenTs with Heart Failure with Preserved Ejection Fraction (PURSUIT HFpEF) study, a prospective multicentre observational registry for ADHF‐HFpEF in Osaka. The data of 870 patients were analysed after excluding patients with in‐hospital death, missing follow‐up data, missing data of serum chloride level, or on chronic dialysis therapy. The primary endpoint of this study was all‐cause mortality. At discharge, right ventricular systolic dysfunction was significantly associated with the lowest tertile of serum chloride level after multivariable adjustment (P = 0.0257). During a mean follow‐up period of 1.8 ± 1.0 years, 186 patients died. Cox multivariable analysis showed that serum chloride level at discharge (P = 0.0017) was independently associated with all‐cause mortality after multivariable adjustment of major confounders, whereas serum sodium level was no longer significant (P = 0.6761). Kaplan–Meier survival curve analysis revealed a significantly increased risk of mortality stratified by the tertile of serum chloride level [29% vs. 19% vs. 16%, P = 0.0002; hazard ratio (HR): 2.09 (95% confidence interval, CI: 1.31 to 3.34), HR: 1.03 (95% CI: 0.65 to 1.64)].

Conclusions

Serum chloride level was useful for the prediction of poor outcome in ADHF patients with preserved ejection fraction.

Chloride in Heart Failure: The Neglected Electrolyte

The increasing burden of heart failure (HF) and emerging knowledge regarding chloride as a prognostic marker in HF have increased the interest in the pathophysiology and interactions of chloride abnormalities with HF-related factors and treatments. Chloride is among the major electrolytes that play a unique role in fluid homeostasis and is associated with cardiorenal and neurohormonal systems. This review elucidates the role of chloride in the pathophysiology of HF, evaluates the effects of treatment on chloride (eg, diuretic agents cause higher urinary chloride excretion and consequently serum hypochloremia), and discusses recent evidence for the association between chloride levels and mortality.

Chloride in Heart Failure Syndrome: Its Pathophysiologic Role and Therapeutic Implication

Until recently, most studies of heart failure (HF) focused on body fluid dynamics through control of the sodium and water balance in the body. Chloride has remained largely ignored in the medical literature, and in clinical practice, chloride is generally considered as an afterthought to the better-known electrolytes of sodium and potassium. In recent years, however, the important role of chloride in the distribution of body fluid has emerged in the field of HF pathophysiology. Investigation of HF pathophysiology according to the dynamics of serum chloride is rational considering that chloride is an established key electrolyte for tubulo-glomerular feedback in the kidney and a possible regulatory electrolyte for body fluid distribution. The present review provides a historical overview of HF pathophysiology, followed by descriptions of the recent attention to the electrolyte chloride in the cardiovascular field, the known role of chloride in the human body, and recent new findings regarding the role of chloride leading to the proposed ‘chloride theory’ hypothesis in HF pathophysiology. Next, vascular and organ congestion in HF is discussed, and finally, a new classification and potential therapeutic strategy are proposed according to the ‘chloride theory’.

Proposal for New Classification and Practical Use of Diuretics According to Their Effects on the Serum Chloride Concentration: Rationale Based on the "Chloride Theory"

Currently, diuretic therapy for heart failure (HF) pathophysiology is primarily focused on the sodium and water balance. Over the last several years, however, chloride (Cl) has been recognized to have an important role in HF pathophysiology, as both a prognostic marker and a possible central factor regulating the body fluid status. I recently proposed a unifying hypothesis for HF pathophysiology, called the "chloride theory", during HF worsening and recovery, as follows. Chloride is the key electrolyte for regulating both reabsorption of tubular electrolytes and water in the kidney through the renin-angiotensin-aldosterone system and distributing body fluid in each compartment of the body. As changes between the serum Cl concentration and plasma volume are intimately associated with worsening HF and its recovery after decongestive therapy, modulation of the serum Cl concentration by careful selection and combination of various diuretics and their doses could become an attractive therapeutic option for HF. In this review, I will propose a new classification and practical use of diuretics according to their effects on the serum Cl concentration. Diuretic use according to this classification is expected to be a useful strategy for the treatment of patients with HF.

Effusion-Serum Chloride Gradient in Heart Failure-Associated Pleural Effusion - Pathophysiologic Implications

Background: There is scant clinical data of electrolyte analyses in the pleural fluid under heart failure (HF) pathophysiology.

Methods and Results: This study retrospectively analyzed data from 17 consecutive patients who presented with pleural effusion and underwent thoracentesis. A diagnosis of worsening HF was established by clinical criteria (presentation, echocardiography, serum B-type natriuretic peptide, and response to therapy). Samples of non-heparinized pleural fluid and peripheral venous blood, obtained within 2 h of each other, were subjected to biochemical analysis. The source of pleural effusion was determined as transudate or exudate according to Light’s criteria. Fifteen patients (53% men; mean [±SD] age 85±11 years) had HF-associated pleural effusion, 10 of whom had transudative effusion and 5 who had exudative effusion (fulfilling only 1 [n=4] or both [n=1] lactate dehydrogenase criteria). The effusion-serum gradient (calculated by subtracting the serum electrolyte concentration from the effusion electrolyte concentration) was significantly higher for chloride (mean [±SD] 7.4±2.6 mEq/L; range 4–14 mEq/L) than sodium (0.9±1.4 mEq/L; ranging from −1 to 4 mEq/L) and potassium (−0.1±0.3 mEq/L; ranging from −0.8 to 0.2 mEq/L; P<0.001 for each).

Conclusions: In HF-associated pleural effusion, the chloride concentration is higher in the pleural effusion than the serum, indicating that chloride may have an important role in the formation and retention of body fluid in the pleural space.

Acute heart failure: More questions than answers

Acute heart failure (AHF) is a life-threatening condition with a dramatic burden in terms of symptoms, morbidity and mortality. It is a specific syndrome requiring urgent, life-saving treatment. Multiple specific pathophysiologic mechanisms may be involved, including congestion, inflammation, and neurohormonal activation. This process eventually leads to symptoms, end-organ damage, and adverse outcomes. Clinical presentation varies, but it almost universally includes worsening of congestion associated with different degrees of hypoperfusion. Due to substantial early symptoms burden and high morbidity and mortality, patients with AHF require intensive monitoring and intravenous treatment. However, beyond variable improvement in congestion, none of the available intravenous therapies for AHF was shown to improve longer term outcomes. Although oral treatment with guideline-directed therapies for stable patients with HF and reduced ejection fraction (HFrEF) before discharge may fully prevent subsequent episodes, proof that this strategy may benefit patients is lacking. First, most patients with AHF have preserved EF (HFpEF) where no therapies have been shown to be effective. Second, all therapies developed for patients with HFrEF were tested for efficacy on outcomes in patients who were stable without recent AHF. Hence, the implementation of these chronic therapies during an AHF episode is untested. Third, the problem to better treat AHF patients in their early phase remains crucial with treatment strategies largely untested, yet. Further studies targeting AHF specific mechanisms, such as inflammation and end-organ damage, and finding effective intravenous drugs remain therefore warranted.

Enhancement of the serum chloride concentration by administration of sodium-glucose cotransporter-2 inhibitor and its mechanisms and clinical significance in type 2 diabetic patients: a pilot study

BACKGROUND

Chloride is a key electrolyte that regulates the body fluid distribution. Accordingly, manipulating chloride kinetics by selecting a suitable diuretic could be an attractive strategy for correcting body fluid dysregulation. Therefore, this study examined the effects and contributing factors of a sodium-glucose cotransporter-2 inhibitor (SGLT2i) on the serum chloride concentration in type 2 diabetic (T2DM) patients without heart failure (HF).

METHODS

This study was a retrospective single-center observational study that enrolled 10 T2DM/non-HF outpatients for whom the SGLT2i empagliflozin (daily oral dose of 10 mg) was prescribed. Among these 10 patients, 6 underwent detailed clinical testing that included hormonal and metabolic blood tests.

RESULTS

Empagliflozin treatment for 1-2 months decreased body weight (- 2.69 ± 1.9 kg; p = 0.002) and HbA1c (- 0.88 ± 0.55%; p = 0.0007). The hemoglobin (+ 0.27 ± 0.36 g/dL; p = 0.04) and hematocrit (+ 1.34 ± 1.38%; p = 0.014) values increased, but the serum creatinine concentration remained unchanged. The serum chloride concentration increased from 104 ± 3.23 to 106 ± 2.80 mEq/L (p = 0.004), but the sodium and potassium concentrations did not change. The spot urinary sodium concentration decreased from 159 ± 43 to 98 ± 35 mEq/L (p < 0.02) and the spot urinary chloride tended to decrease (from 162 ± 59 to 104 ± 36 mEq/L, p < 0.08). Both renin and aldosterone tended to be activated (5/6, 83%). The strong organic acid metabolite concentrations of serum acetoacetate (from 42 ± 25 to 100 ± 45 μmol/L, p < 0.02) and total ketone bodies (from 112 ± 64 to 300 ± 177 μmol/L, p < 0.04) increased, but the actual HCO3 - concentration decreased (from 27 ± 2.5 to 24 ± 1.6 mEq/L, p < 0.008).

CONCLUSIONS

The present study demonstrated that SGLT2i enhances the serum chloride concentration in T2DM patients and suggests that the effect is mediated by the possible following mechanisms: (1) enhanced reabsorption of urinary chloride by aldosterone activation due to blood pressure lowering and blood vessel contraction effects, (2) reciprocal increase in the serum chloride concentration by reducing the serum HCO3 - concentration via a buffering effect of strong organic acid metabolites, and (3) reduced NaHCO3 reabsorption and concurrently enhanced chloride reabsorption in the urinary tubules by inhibiting Na+-H+ exchanger 3 in the renal proximal tubules. Thus, the diuretic SGLT2i induces excessive extravascular fluid to drain into the vascular space by the enhanced vascular "tonicity" caused by the elevated serum chloride concentration.

Comparison of Changes in Plasma Volume and Renal Function between Acetazolamide and Conventional Diuretics: Understanding the Mechanical Differences according to the "Chloride Theory"

OBJECTIVE

We compared the effects of the chloride-regaining diuretic acetazolamide with those of conventional diuretics on plasma volume, serum electrolytes, and renal function in acutely decompensated heart failure (HF) patients.

METHODS

A retrospective analysis was performed on the data of 13 patients treated with acetazolamide (Group A) and 13 patients with conventional diuretics (Group B) matched based on diuresis-induced weight reduction (≥1 kg) during resolution of worsening HF. Changes in plasma volume (Strauss formula), renal function, and serum electrolytes under treatment were determined by peripheral blood tests.

RESULTS

Clinical characteristics at baseline were not different between groups A and B. After diuretic therapy, body weight reduction (-2.23 ± 1.11 vs. -2.22 ± 1.06 kg, p = 0.97) and the number of residual HF-related signs (0.31 ± 0.48 vs. 0.23 ± 0.44, p = 0.67) was not different between groups. After each treatment, the serum chloride concen-tration increased in Group A, but decreased in Group B (+5.31 ± 4.91 vs. - 4.54 ± 4.68 mEq/L, p < 0.0001). Plasma volume (0.63 ± 13.1 vs. -12.1 ± 10.5%, p < 0.01) and renal function determined by changes in serum creatinine concentration (0.048 ± 0.12 vs. 0.21 ± 0.24 mg/dL, p < 0.047) were preserved in Group A compared with Group B.

CONCLUSIONS

While both groups exhibited equivalent body weight reduction and resolution of HF-related signs after each diuretic treatment, acetazolamide treatment preserved plasma volume and renal function compared to conventional diuretics.

Highlights in heart failure

Heart failure (HF) remains a major cause of mortality, morbidity, and poor quality of life. It is an area of active research. This article is aimed to give an update on recent advances in all aspects of this syndrome. Major changes occurred in drug treatment of HF with reduced ejection fraction (HFrEF). Sacubitril/valsartan is indicated as a substitute to ACEi/ARBs after PARADIGM-HF (hazard ratio [HR], 0.80; 95% confidence interval [CI], 0.73 to 0.87 for sacubitril/valsartan vs. enalapril for the primary endpoint and Wei, Lin and Weissfeld HR 0.79, 95% CI 0.71-0.89 for recurrent events). Its initiation was then shown as safe and potentially useful in recent studies in patients hospitalized for acute HF. More recently, dapagliflozin and prevention of adverse-outcomes in DAPA-HF trial showed the beneficial effects of the sodium-glucose transporter type 2 inhibitor dapaglifozin vs. placebo, added to optimal standard therapy [HR, 0.74; 95% CI, 0.65 to 0.85;0.74; 95% CI, 0.65 to 0.85 for the primary endpoint]. Trials with other SGLT 2 inhibitors and in other patients, such as those with HF with preserved ejection fraction (HFpEF) or with recent decompensation, are ongoing. Multiple studies showed the unfavourable prognostic significance of abnormalities in serum potassium levels. Potassium lowering agents may allow initiation and titration of mineralocorticoid antagonists in a larger proportion of patients. Meta-analyses suggest better outcomes with ferric carboxymaltose in patients with iron deficiency. Drugs effective in HFrEF may be useful also in HF with mid-range ejection fraction. Better diagnosis and phenotype characterization seem warranted in HF with preserved ejection fraction. These and other burning aspects of HF research are summarized and reviewed in this article.

Acetazolamide as a potent chloride-regaining diuretic: short- and long-term effects, and its pharmacologic role under the 'chloride theory' for heart failure pathophysiology

According to the "chloride theory" for heart failure (HF) pathophysiology, manipulation of the serum chloride concentration is an important therapeutic target. This study determined the short- and long-term effects of acetazolamide (Diamox), a potential chloride-regaining diuretic, on peripheral blood, serum electrolytes, and renal function. Effects of low-dose Diamox (250-500 mg/day) were evaluated in 30 HF patients for whom Diamox was added as de-novo/add-on decongestion therapy for acutely worsening HF (n = 18) or as modification therapy for serum hypochloremia in stable HF ( < 100 mEq/L; n = 12). Peripheral hematologic tests were performed at baseline, and at short- ( ≤ 10 days) and long-term ( ~ 60 days) time-points. In all 30 study patients of both groups, the serum chloride concentration increased in the short-term and even further over the long-term. The serum potassium concentration constantly decreased throughout the study period. Both the blood urea nitrogen and serum creatinine concentrations increased in the short-term, but returned to baseline levels over the long-term. Responders to Diamox (n = 13; defined by HF resolution and body weight loss ≥ 1 kg) in the decongestion group exhibited reduced serum b-type natriuretic peptide levels and a markedly increased serum chloride concentration, but the hemoglobin/hematocrit and serum creatinine concentrations did not change after treatment. In conclusion, acetazolamide is a potent candidate "chloride-regaining diuretic" for treating HF patients under the "chloride theory". Its effect to enhance the serum chloride concentration occurred within 10 days and persisted for at least ~ 60 days. Plasma volume and renal function were preserved under adequate diuretic treatment with acetazolamide.

"I don't get no respect": the role of chloride in acute kidney injury

Acute kidney injury (AKI) is a major public health problem that complicates 10-40% of hospital admissions. Importantly, AKI is independently associated with increased risk of progression to chronic kidney disease, end-stage renal disease, cardiovascular events, and increased risk of in-hospital and long-term mortality. The chloride content of intravenous fluid has garnered much attention over the last decade, as well as its association with excess use and adverse outcomes, including AKI. Numerous studies show that changes in serum chloride concentration, independent of serum sodium and bicarbonate, are associated with increased risk of AKI, morbidity, and mortality. This comprehensive review details the complex renal physiology regarding the role of chloride in regulating renal blood flow, glomerular filtration rate, tubuloglomerular feedback, and tubular injury, as well as the findings of clinical research related to the chloride content of intravenous fluids, changes in serum chloride concentration, and AKI. Chloride is underappreciated in both physiology and pathophysiology. Although the exact mechanism is debated, avoidance of excessive chloride administration is a reasonable treatment option for all patients and especially in those at risk for AKI. Therefore, high-risk patients and those with "incipient" AKI should receive balanced solutions rather than normal saline to minimize the risk of AKI.

Dynamic changes in serum chloride concentrations during worsening of heart failure and its recovery following conventional diuretic therapy: A single-center study

BACKGROUND AND AIMS

Few data are available regarding the dynamic changes in the serum chloride concentrations in heart failure (HF) pathophysiology. The aim of the present study was to investigate changes in the serum chloride concentration under worsening HF and its recovery following conventional diuretic therapy.

METHODS

Blood test data, including measurements of serum albumin/solutes and b-type natriuretic peptide, at both worsening and recovery of HF status, were obtained from 47 patients with definite HF.

RESULTS

Ambulatory patients with HF were enrolled and followed up at the outpatient clinic of Nishida Hospital between June 2003 and March 2009. From clinically stable to worsening HF, the serum sodium concentration increased from (mean ± SD) 139 ± 4.1 to 141 ± 5.07 mEq/L (P < 0.05, two-way analysis of variance) and the serum chloride concentration increased from 101 ± 5.36 to 104 ± 5.44 mEq/L (P < 0.01) among all patients. After resolution of worsening HF by treatment with conventional diuretics, both the serum sodium concentration and serum chloride concentration decreased significantly to 138 ± 5.12 and 99.5 ± 5.33 mEq/L, respectively (P < 0.0001 for each). The absolute changes in the serum sodium concentration from clinically stable HF to worsening HF appeared to be lesser than those in the serum chloride concentration (1.70 ± 4.34 vs 2.72 ± 6.02 mEq/L, P = 0.079, t test), but this was not statistically significant. Absolute changes in the serum sodium concentration from worsening HF to its recovery following treatment with conventional diuretics were lesser than those in the serum chloride concentration (-2.87 ± 4.38 vs -4.45 ± 5.23 mEq/L, P = 0.0068, t test).

CONCLUSION

Under conventional diuretic therapy, greater changes occur in the serum chloride concentration than in the serum sodium concentration under HF state transitions, suggesting that chloride dynamics might contribute more to HF pathophysiology under such therapeutic circumstance.

Vasopressin antagonist-like effect of acetazolamide in a heart failure patient: a case report

Background

Hyponatraemia is easily corrected by treatment with an oral vasopressin antagonist, but these medications are costly and their use at outpatient clinics is restricted by government-managed insurance in Japan. Acetazolamide could be an alternative diuretic to a vasopressin antagonist.

Case Summary

An 83-year-old dyspnoeic male patient was emergently admitted to the hospital due to decompensated heart failure (HF), hypotension, and hyperkalaemia-associated sinus arrest with a junctional escape rhythm. Urgent treatment with a noradrenaline drip infusion and a beta stimulant adhesive skin patch promptly restored sinus rhythm with conducted normal QRS complex, which resolved the hypotension. Blood tests on admission revealed moderately elevated b-type natriuretic peptide (BNP, 576 pg/mL), hyponatraemia (128 mEq/L), hypochloraemia (95 mEq/L), hyperkalaemia (5.7 mEq/L), and preserved renal function (creatinine, 1.0 mg/dL) under no cardiovascular medications. Immediately after admission, low-dose oral acetazolamide (500 mg/day) and polystyrene sulfonate-Ca jelly (Argamate, 25 g/day for 3 days) were prescribed to correct the decompensated HF status and electrolyte disturbance. Three days later, both the serum sodium and chloride concentrations had recovered to normal levels (136 mEq/L and 104 mEq/L, respectively), and the serum potassium concentration had decreased to 4.5 mEq/L. Two weeks later, the patient’s HF status became stable and the serum BNP concentration returned to normal (55 pg/mL).

Discussion

The present case indicates that the classic diuretic of acetazolamide would have a vasopressin blockade-like effect and could be an alternative diuretic to vasopressin antagonists for some proportion of HF patients with hyponatraemia.

Changes in red blood cell volume during transition of heart failure status: a reflection of cellular hydration status?

This study examined how changes in heart failure (HF) status induce changes in the index of erythrocyte hydration based on mean red blood cell volume (MCV). Data from 47 HF patients (32% men; 78.2 ± 9.7 years) that experienced worsening and recovery of HF were analysed. Blood tests included measurements of MCV, albumin, serum solutes and b-type natriuretic peptide (BNP). Among a total of 47 worsening HF events, changes in MCV were positively correlated with changes in body weight (r = 0.31, p = .034), serum sodium (r = 0.417, p = .0036), and chloride (r = 0.457, p = .0012), and negatively correlated with changes in blood urea nitrogen (r= -0.389, p = .0069) and creatinine (r= -0.494, p = .0004). At recovery from worsening of HF by conventional diuretic therapy, change in MCV was positively correlated with the change in body weight (r = 0.457, p = .0012), serum sodium (r = 0.466, p = .001) and chloride (r = 0.484, p = .0006). Multivariate regression analysis demonstrated an independent association between the increase in serum chloride and MCV from stability to worsening of HF (odds ratio [OR] 6.02, 95% confidence interval [CI] 1.09-33.2, p = .039) and the increase or absence of change in serum chloride concentration and preserved MCV after decongestion (OR 11.5, 95% CI 1.53-85.9, p = .017). In conclusion, this study demonstrates that the changes in MCV under transition in HF status do not reflect a change that occurs in parallel with changes in HF-related markers, such as body weight and serum BNP level, but is independently associated with a change in the serum chloride concentration. Whether changes in MCV actually reflect the bodily cellular hydration status warrants further research.

Treatment of hypochloremia with acetazolamide in an advanced heart failure patient and importance of monitoring urinary electrolytes

Chloride was recently recognized to play an important role in the pathophysiology of heart failure (HF). Chloride manipulation, including the use of acetazolamide, may be a requisite therapeutic target in HF treatment. An 87-year-old male patient with advanced HF and hypertrophic cardiomyopathy was admitted to the hospital due to hypochloremia (94 mEq/L) and hyponatremia (134 mEq/L) under diuretic treatment with azosemide, spironolactone, and tolvaptan. On admission, HF-related signs of overhydration were lacking, but B-type natriuretic peptide was moderately elevated. The etiology of the hypochloremia/natremia state was depletion of both electrolytes based on serum analysis and spot urinary concentrations. Immediately after admission, acetazolamide (500 mg/d) was prescribed to correct the hypochloremia in parallel with cessation of the preceding administration of azosemide and spironolactone, and tapering off of the tolvaptan over 7 days. Under treatment, both serum chloride and sodium concentrations recovered to normal (108 mEq/L and 148 mEq/L, respectively), and the serum potassium concentration decreased from 3.9 mEq/L to 2.4 mEq/L. Urinary concentrations of sodium and potassium increased from 18 mEq/L to 31 mEq/L and from 19 mEq/L to 51.5 mEq/L respectively, in concordance with the changes in serum concentrations, but the chloride concentration decreased from 18 mEq/L to 12 mEq/L, opposite the changes in the serum concentration. <Learning objective: The present case confirms that the classic drug acetazolamide, although rarely used now for HF treatment, is a potent "chloride-regaining" or "chloride-retaining diuretic" with concomitant activity to reduce serum potassium. Additionally, this case study highlights the importance of monitoring both serum and urinary electrolyte concentrations to determine the electrolyte disturbance and efficacy of diuretic treatment through analytic evaluation of changes in the serum electrolytes and their tubular reabsorption in the kidney.>.

Proposal for heart failure progression based on the 'chloride theory': worsening heart failure with increased vs. non-increased serum chloride concentration

AIMS

Chloride (Cl) is an established key electrolyte for the activation of the renin-angiotensin-aldosterone system. Recent studies have shown the serum Cl as a key electrolyte for the regulation of body fluid distribution in heart failure (HF) patients. The clinical differences of worsening HF status according to the changes in serum Cl concentration are unclear.

METHODS AND RESULTS

Data from 47 chronic HF patients were analysed. Upon worsening HF, each patient exhibited at least two HF-related signs. Blood tests included haemoglobin (Hb), haematocrit (Ht), mean red blood cell volume (MCV), albumin, serum solutes, and b-type natriuretic peptide. The relative change in the plasma volume (%PV) from stable to worsening HF was estimated as follows: 100 × {Hb (stable) × [1 - Ht (worse)]}/{Hb (worse) × [1 - Ht (stable)]} - 100. When patients were divided into two groups based on changes in serum Cl concentration from stable to worsening HF, the pathophysiologic features of the patients with increased Cl (range 1-23 mEq/L; n = 31) included a greater increase in serum sodium (2.94 ± 4.15 vs. -0.69 ± 3.75 mEq/L, P = 0.005), higher vascular expansion (12 ± 11.1 vs. 4.81 ± 7.94%, P = 0.026), a tendency towards a greater MCV (1.23 ± 2.36 vs. -0.06 ± 1.88 fL, P = 0.065), and preserved renal function defined by the absence of an increase of serum creatinine (-0.24 ± 0.39 vs. -0.05 ± 0.12 mg/dL, P = 0.057) compared to patients with non-increased Cl (range -9 to 0 mEq/L; n = 16). Clinically, the increased Cl group had fewer HF signs (2.65 ± 0.71 vs. 3.31 ± 0.79, P = 0.005) although the change in symptoms did not differ between groups (48% vs. 63%, P = 0.54).

CONCLUSIONS

The present study suggests a new clinical entity of worsening HF status, that is, HF with increased vs. non-increased serum Cl concentration from clinical stability to worsening HF.