Serum potassium levels provide prognostic information in symptomatic heart failure beyond traditional clinical variables

Six-minute walk test as clinical end point in cardiomyopathy clinical trials, including ATTR-CM: a systematic literature review

Aim: The six-minute walk test (6MWT) is a common measure of functional capacity in patients with heart failure (HF). Primary clinical study end points in cardiomyopathy (CM) trials, including transthyretin-mediated amyloidosis with CM (ATTR-CM), are often limited to hospitalization and mortality. Objective: To investigate the relationship between the 6MWT and hospitalization or mortality in CM, including ATTR-CM. Method: A PRISMA-guided systematic literature review was conducted using search terms for CM, 6MWT, hospitalization and mortality. Results: Forty-one studies were identified that reported 6MWT data and hospitalization or mortality data for patients with CM. The data suggest that a greater 6MWT distance is associated with a reduced risk of hospitalization or mortality in CM. Conclusion: The 6MWT is an accepted alternative end point in CM trials, including ATTR-CM.

Relationship between Baseline Serum Potassium and 1-Year Readmission in Pediatric Patients with Heart Failure: A Retrospective Cohort Study

Pediatric heart failure (HF) is associated with high readmission rates, but the optimal serum potassium range for this population remains unclear. In this single-center retrospective cohort study, 180 pediatric patients hospitalized for HF between January 2016 and January 2022 were stratified into low-potassium (<3.7 mmol/L), middle-potassium (3.7-4.7 mmol/L), and high-potassium (≥4.7 mmol/L) groups based on the distribution of potassium levels in the study population. The primary outcome was readmission for HF within 1 year of discharge. Cox regression and restricted cubic spline models were used to assess the association between potassium levels and 1-year HF readmission rates. Notably, 38.9% of patients underwent 1 or more 1-year readmissions for HF within 1 year. The high-potassium group had a significantly higher readmission frequency than the middle-potassium group. In multivariate Cox regression models, potassium levels of ≥4.7 mmol/L were independently associated with increased 1-year readmission risk. A J-shaped relationship was observed between baseline potassium levels and 1-year readmission risk, with the lowest risk at 4.1 mmol/L. In pediatric patients with HF, a serum potassium level ≥ 4.7 mmol/L was independently associated with increased 1-year readmission risk. Maintaining potassium levels within a narrow range may improve outcomes in this population.

Pleiotropic Effects of Sodium-Glucose Cotransporter-2 Inhibitors in Cardiovascular Disease and Chronic Kidney Disease

Sodium-glucose cotransporter-2 inhibitors (SGLT2is) have been shown to improve cardiovascular and renal outcomes in patients with established cardiovascular disease, chronic kidney disease (CKD), and heart failure (HF) with reduced or preserved ejection fraction. Clinical benefit has been substantiated in patients with and without type 2 diabetes (T2D). Consequently, SGLT2is have an increasingly important role in HF and CKD management that extends beyond T2D treatment. Their pleiotropic pharmacological effects underlying their cardiovascular and renal benefits are not completely understood but include significant effects beyond blood glucose reduction. SGLT2is inhibit the reabsorption of glucose and sodium in the proximal tubule which, in addition to lowering blood glucose, activates tubuloglomerular feedback, leading to reduced glomerular hydrostatic pressure and the mitigation of glomerular filtration rate loss. SGLT2is have diuretic and natriuretic effects, leading to decreased blood pressure, preload, and left ventricular (LV) filling pressure, and improvements in other surrogates of afterload. In HF, SGLT2is mitigate the risks of hyperkalemia and ventricular arrhythmia and improve LV dysfunction. SGLT2is also reduce sympathetic tone and uric acid levels, increase hemoglobin levels, and are postulated to have anti-inflammatory properties. This narrative review discusses the multifactorial and interrelated pharmacological mechanisms underlying the cardiovascular and renal benefits of SGLT2is.

Serum potassium in elderly heart failure patients as a predictor of readmission within 1 year

Blood potassium levels are associated with adverse outcomes in patients with congestive heart failure (HF). However, it is unclear whether there are differences in outcome events in elderly patients with different blood potassium levels at the time of emergency readmission within 1 year. This study used data from patients hospitalized with HF, integrating electronic medical records from the PhysioNet restricted health data database and external outcome data. We conducted a retrospective study of HF patients aged 60 years and older, using baseline data, comorbidities, laboratory tests, and medication use as covariates to analyze the effect of serum potassium levels on outcome events, with the primary outcome being readmission within 1 year. A priori was used to calculate the sample size, and this retrospective cohort study included a total of 788 elderly HF patients, of whom 20.3% had hypokalaemia (K⁺  < 3.5 mmol/L) and 14.7% had hyperkalemia (K⁺  > 4.7 mmol/L). According to a multivariate Cox regression model, patients with hyperkalemia had a shorter time interval between readmissions within 1 year, with a hazard ratio (HR) and its 95% CI of 1.134 (1.006-1.279). Three models were used to analyze patients with different blood potassium levels and, after correction, the high potassium group was at high risk relative to the low and normal groups, with significant differences in outcome events, with HRs and their 95% CI of 1.266 (1.03-1.557), 1.245 (1.01-1.534), and 1.439 (1.142-1.812), respectively. The robustness of the model was also demonstrated by competing risk models with subgroup analysis, showing that blood potassium levels had a stable effect on outcome events and were not altered by covariates (age, sex, diabetes, chronic kidney disease, NT-proBNP, high-sensitivity troponin, and glomerular filtration rate). The results show that high blood potassium levels are associated with the outcome event of readmission within 1 year in elderly patients with HF. Blood potassium levels at the time of the first hospitalization may therefore be a valuable predictor.

Glycine protects against doxorubicin-induced heart toxicity in mice

Doxorubicin (DOXO) is a well-known cancer chemotherapeutic. However, its toxic effect on the heart limits its clinical application. This study aimed to assess the effectiveness of glycine administration to counteract the DOXO-induction of cardiomyopathy in mice. Fifty male albino mice were divided into five groups (n = 10/group) as follows: control, DOXO, Gp100, Gp150, and Gp200. Histopathological examination of the heart, and biochemical examinations for heart function (creatine phosphokinase (CPK), lactate dehydrogenase (LDH), and aspartate aminotransferase (AST)), inflammation (tumor necrosis factor-alpha (TNF-α) and interleukin 10 (IL-10)), oxidative stress (malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD), catalase, nitric oxide (NO), and uric acid), kidney function (urea and creatinine), and minerals (calcium, phosphorus, sodium, and potassium) were carried out. Cardiomyopathy induced by DOXO treatment (15 mg/kg total dose) was ascertained via pathological alterations seen in heart tissue and verified biochemically via increases (P < 0.001) in CPK, LDH, AST, TNF-α, IL-10, MDA, NO, Na, and K levels along with decreases (P < 0.001) in GSH, SOD, catalase, and uric acid. Glycine co-treatment, using doses of 100, 150, and 200 mg/kg, in a dose-dependent manner, displayed ameliorated heart architecture, significantly (P < 0.001) improved biochemical heart function tests, reduced oxidative stress and inflammation, and controlled mineral levels. The positive actions of glycine in DOXO-induced cardiotoxicity amelioration via modulating oxidative stress, inflammation, and immunity are confirmed. Glycine antioxidative properties may be behind its positive outcomes. Finally, we present glycine as a worthy possible option against DOXO-induced heart damage after more validation.

Serum potassium levels provide prognostic information in symptomatic heart failure beyond traditional clinical variables

Aims

Despite of recent advances in the pharmacological treatment, heart failure (HF) maintains significant morbidity and mortality rates. While serum potassium disorders are common and associated with adverse outcomes, the exact recommended potassium level for patients with HF are not entirely established. We aimed to investigate the prognostic role of potassium levels on a cohort of patients with symptomatic chronic HF.

Methods and results

Patients with symptomatic chronic HF were identified at the referral to 6 min walking test (6MWT) and were prospectively followed up for cardiovascular events. Clinical and laboratorial data were retrospectively obtained. The primary endpoint was the composite of cardiovascular death, hospitalization due to HF, and heart transplantation. The cohort included 178 patients with HF with the mean age of 51 ± 12.76 years, 39% were female, 85% of non‐ischaemic cardiomyopathy, and 38% had New York Heart Association Class III with a relatively high Meta‐Analysis Global Group in Chronic Heart Failure (MAGGIC) score (12.91 ± 6.6). The mean left ventricular ejection fraction was 39.98 ± 15.79%, and the mean 6MWT distance was 353 ± 136 m. After a median follow‐up of 516 days, there were 22 major cardiovascular events (4 cardiovascular deaths, 13 HF admissions, and 5 heart transplants). Patients were stratified according to cut‐point level of serum potassium of 4.7 mmol/L to predict combined cardiac events based on receiver operating characteristic analysis. Individuals with higher potassium levels had worse renal function (glomerular filtration rate, K ≤ 4.7: 102.8 ± 32.2 mL/min/1.73 m² vs. K > 4.7: 85.42 ± 36.2 mL/min/1.73 m², P = 0.004), higher proportion of New York Heart Association Class III patients (K ≤ 4.7: 28% vs. K > 4.7: 48%, P = 0.0029), and also higher MAGGIC score (K ≤ 4.7: 12.08 ± 5.7 vs. K > 4.7: 14.9 ± 7.9, P = 0.0089), without significant differences on the baseline pharmacological HF treatment. Both potassium levels [hazard ratio (HR) 4.26, 95% confidence interval (CI) 1.59–11.421, P = 0.003] and 6MWT distance (HR 0.99, 95% CI 0.993–0.999, P = 0.01) were independently associated with the primary outcome. After adjustments for MAGGIC score and 6MWT distance, potassium levels > 4.7 mmol/L maintained a significant association with outcomes (HR 3.57, 95% CI 1.305–9.807, P = 0.013). Patients with K > 4.7 mmol/L were more likely to present clinical events during the follow‐up (log rank = 0.005). Adding potassium levels to the model including 6MWT and MAGGIC significantly improved the prediction of events over 2 years (integrated discrimination index 0.105, 95% CI 0.018–0.281, P = 0.012 and net reclassification index 0.447, 95% CI 0.077–0.703, P = 0.028).

Conclusions

Potassium levels were independently associated with worse outcomes in patients with chronic symptomatic HF, also improving the accuracy model for prognostic prediction when added to MAGGIC score and 6MWT distance. The potassium levels above 4.7 mmol/L might identify those patients at an increased risk of cardiovascular events.