Relationship between serum iron level and physical function in heart failure patients is lost by presence of diabetes

Abstract Aims Iron deficiency (ID) is common in patients with heart failure (HF) and is reportedly associated with exercise intolerance and impaired quality of life. Iron supplementation therapy in HF patients with ID improves exercise capacity. Conversely, protective roles of iron depletion in the development of diabetes mellitus (DM) and its complications have been proposed. This study aimed to determine the impact of ID on physical function in HF patients with and without DM. Methods and results We enrolled consecutive patients who were admitted to our institute for HF diagnosis and management. The short physical performance battery (SPPB) was used to evaluate physical function, and low physical function was defined as an SPPB score of <10 points as individuals with SPPB scores of <10 points are most likely to be classified as frail and are at high risk for disability and future adverse events, including death. ID was defined as serum ferritin < 100 or 100–299 ng/mL when transferrin saturation (TSAT) was <20% according to the HF guidelines. Among the 562 HF patients (72 ± 14 years old; 56% male), 329 patients (58%) and 191 patients (34%) had ID and low physical function, respectively. Multivariate logistic regression analysis showed that TSAT as a continuous variable, but not ID, was a predictor of low physical function (odds ratio: 0.980, P = 0.024). Subgroup analysis showed that a significant association between low TSAT and low physical function was lost in HF patients with DM (P for interaction < 0.001). A spline dose–response curve for the relationship between TSAT and risk of low physical function with adjustments for covariates associated with low physical function in non‐DM patients was almost linear with an increase in the risk of low physical function as the TSAT increased, but such a relationship was not found in the analyses of DM patients. A lack of close TSAT–SPPB relationship in HF patients with DM was confirmed also in a propensity‐score‐matched cohort. Conclusions TSAT as a continuous variable, but not ID, was independently associated with physical function in HF patients, and a significant association was lost in patients with HF and DM, suggesting a limited impact of iron supplementation therapy in HF patients with DM

Enhanced nuclear localization of phosphorylated MLKL predicts adverse events in patients with dilated cardiomyopathy

Abstract Aims The role of necroptosis in dilated cardiomyopathy (DCM) remains unclear. Here, we examined whether phosphorylation of mixed lineage kinase domain‐like protein (MLKL), an indispensable event for execution of necroptosis, is associated with the progression of DCM. Methods and results Patients with DCM (n = 56, 56 ± 15 years of age; 68% male) were enrolled for immunohistochemical analyses of biopsies. Adverse events were defined as a composite of death or admission for heart failure or ventricular arrhythmia. Compared with the normal myocardium, increased signals of MLKL phosphorylation were detected in the nuclei, cytoplasm, and intercalated discs of cardiomyocytes in biopsy samples from DCM patients. The phosphorylated MLKL (p‐MLKL) signal was increased in enlarged nuclei or nuclei with bizarre shapes in hypertrophied cardiomyocytes. Nuclear p‐MLKL level was correlated negatively with septal peak myocardial velocity during early diastole (r = −0.327, P = 0.019) and was correlated positively with tricuspid regurgitation pressure gradient (r = 0.339, P = 0.023), while p‐MLKL level in intercalated discs was negatively correlated with mean left ventricular wall thickness (r = −0.360, P = 0.014). During a median follow‐up period of 3.5 years, 10 patients (18%) had adverse events. To examine the difference in event rates according to p‐MLKL expression levels, patients were divided into two groups by using the median value of nuclear p‐MLKL or intercalated disc p‐MLKL. A group with high nuclear p‐MLKL level (H‐nucMLKL group) had a higher adverse event rate than did a group with low nuclear p‐MLKL level (L‐nucMLKL group) (32% vs. 4%, P = 0.012), and Kaplan–Meier survival curves showed that the adverse event‐free survival rate was lower in the H‐nucMLKL group than in the L‐nucMLKL group (P = 0.019 by the log‐rank test). Such differences were not detected between groups divided by a median value of intercalated disc p‐MLKL. In δ‐sarcoglycan‐deficient (Sgcd−/−) mice, a model of DCM, total p‐MLKL and nuclear p‐MLKL levels were higher than in wild‐type mice. Conclusion The results suggest that increased localization of nuclear p‐MLKL in cardiomyocytes is associated with left ventricular diastolic dysfunction and future adverse events in DCM