Sudden cardiac death in diabetes and obesity: mechanisms and therapeutic strategies

Sudden Cardiac Death Risk Stratification in Heart Failure With Preserved Ejection Fraction

Heart failure with preserved ejection fraction (HFpEF) poses a significant clinical challenge, with sudden cardiac death (SCD) emerging as one of the leading causes of mortality. Despite advancements in cardiovascular medicine, predicting and preventing SCD in HFpEF remains complex due to multifactorial pathophysiological mechanisms and patient heterogeneity. Unlike heart failure with reduced ejection fraction, where impaired contractility and ventricular remodeling predominate, HFpEF pathophysiology involves heavy burden of comorbidities such as hypertension, obesity, and diabetes. Diverse mechanisms, including diastolic dysfunction, microvascular abnormalities, and inflammation, also contribute to distinct disease and SCD risk profiles. Various parameters such as clinical factors and electrocardiogram features have been proposed in SCD risk assessment. Advanced imaging modalities and biomarkers offer promise in risk prediction, yet comprehensive risk stratification models specific to HFpEF ar0e lacking. This review offers recent evidence on SCD risk factors and discusses current therapeutic strategies aimed at reducing SCD risk in HFpEF.

Classification, Diagnosis, and Treatment of Obesity-Related Heart Diseases

Evidence-based medicine shows that obesity is associated with a wide range of cardiovascular (CV) diseases. Obesity can lead to changes in cardiac structure and function, which can lead to obese cardiomyopathy, subclinical cardiac dysfunction, and even heart failure. It also increases the risk of atrial fibrillation and sudden cardiac death. Many invasive and noninvasive diagnostic methods can detect obesity-related heart disease at an early stage, so that appropriate measures can be selected to prevent adverse CV events. However, studies have shown a protective effect of obesity on clinical outcomes of CV disease, a phenomenon that has been termed the obesity paradox. The "obesity paradox" essentially refers to the fact that the classification of obesity defined by body mass index (BMI) does not consider the impact of obesity heterogeneity on CV disease prognosis, but simply puts subjects with different clinical and biochemical characteristics into the same category. In any case, indicators such as waist-to-hip ratio, ectopic body fat qualitative and quantitative, and CV fitness have been shown to be able to distinguish different CV risks in patients with the same BMI, which is convenient for early intervention in an appropriate way. A multidisciplinary approach, including lifestyle modification, evidence-based generic and novel pharmacotherapy, and surgical intervention, can improve CV outcomes in overweight/obese patients.

Racial Disparities In In-Hospital Mortality of Children and Adolescents Under 20 Years With Type 1 Diabetes Mellitus

BACKGROUND

In the United States, racial disparities in health outcomes continue to be a major problem with far-reaching effects on equity in healthcare and public health. Children and teenagers with type 1 diabetes are a disadvantaged demographic that has particular difficulties in managing their condition and getting access to healthcare. Despite improvements in the treatment of diabetes, little study has examined how much racial disparities in in-hospital mortality affect this particular demographic. By examining racial differences in in-hospital mortality rates among children and adolescents with type 1 diabetes in the United States, this study seeks to close this gap.

METHODS

This cross-sectional study utilized data from the Healthcare Cost and Utilization Project's (HCUP) Kids' Inpatient Database (KID) for 2012. The KID is a nationally representative sample of pediatric discharges from US hospitals. A total of 20,107 patients who were admitted with type 1 diabetes were included in this study. The primary outcome was the patient's in-hospital mortality status. The primary predictor variable was the race of the patient. Six potential confounders were chosen based on previous literature: age, sex, hospital location, obesity, weight loss, electrolyte disorders status, and median household income. Descriptive statistics and bivariate analyses were done. Multivariate analysis was conducted while controlling for potential confounders. Odd ratios with a 95% confidence interval and probability value were reported. Statistical Analysis System (SAS) version 9.4 for Windows (SAS Institute Inc., Cary, NC, USA) was used for the statistical analysis.

RESULTS

A total of 20,107 patients were included in this study. Of the patients included, 78.6%, 5.3%, 5.9%, and 10.2% were of age groups <4, 5-9, 10-14, and 15-18, respectively. Among the patients, 64.3% were female. Whites stood at 54.3%, while Hispanic, Black, and other races accounted for 17.2%, 21.8%, and 6.7% respectively. After adjusting for all other variables, children, and young adults of Asian and Pacific Islanders (OR=1.948; 95% CI 1.015,3.738) had 94% higher odds of in-hospital mortality compared to their White counterparts. Children and young adults aged 5-9 (OR=0.29; 95% CI 0.13,0.649) had 71% lower odds of in-hospital mortality compared to those aged 4 or under. Those aged 10-14 (OR=0.155; 95% CI 0.077,0.313) had 85% lower odds of in-hospital mortality compared to those aged 4 or under, while those aged 15-19 (OR=0.172; 95% CI 0.100,0.296) had 83% lower odds of in-hospital mortality compared to those aged 4 or under. Children and young adults who had weight loss (OR=4.474; 95% CI 2.557,7.826) had almost five times higher odds of in-hospital mortality compared to those without weight loss, while children and young adults who had electrolyte disorders (OR=5.131; 95% CI 3.429,7.679) had five times higher odds of in-hospital mortality compared to those without electrolyte disorders.

CONCLUSION

The results show young adults of Asian and Pacific Islanders have higher odds of in-hospital mortality compared to their White counterparts and this study highlights the urgent need for focused measures designed to lessen these inequalities and enhance health equity. The implementation of culturally sensitive healthcare practices, addressing social determinants of health, and enhancing access to high-quality diabetes care should all be priorities.

SCN5A-1795insD founder variant: a unique Dutch experience spanning 7 decades

The SCN5A-1795insD founder variant is a unique SCN5A gene variant found in a large Dutch pedigree that first came to attention in the late 1950s. To date, this is still one of the largest and best described SCN5A founder families worldwide. It was the first time that a single pathogenic variant in SCN5A proved to be sufficient to cause a sodium channel overlap syndrome. Affected family members displayed features of Brugada syndrome, cardiac conduction disease and long QT syndrome type 3, thus encompassing features of both loss and gain of sodium channel function. This brief summary takes us past 70 years of clinical experience and over 2 decades of research. It is remarkable to what extent researchers and clinicians have managed to gain understanding of this complex phenotype in a relatively short time. Extensive clinical, genetic, electrophysiological and molecular studies have provided fundamental insights into SCN5A and the cardiac sodium channel Nav1.5.

Increased Epicardial Adipose Tissue (EAT), Left Coronary Artery Plaque Morphology, and Valvular Atherosclerosis as Risks Factors for Sudden Cardiac Death from a Forensic Perspective

Background: In sudden cardiac deaths (SCD), visceral adipose tissue has begun to manifest interest as a standalone cardiovascular risk factor. Studies have shown that epicardial adipose tissue can be seen as a viable marker of coronary atherosclerosis. This study aimed to evaluate, from a forensic perspective, the correlation between body mass index (BMI), heart weight, coronary and valvular atherosclerosis, left ventricular morphology, and the thickness of the epicardial adipose tissue (EAT) in sudden cardiac deaths, establishing an increased thickness of EAT as a novel risk factor. Methods: This is a retrospective case−control descriptive study that included 80 deaths that were autopsied, 40 sudden cardiac deaths, and 40 control cases who hanged themselves and had unknown pathologies prior to their death. In all the autopsies performed, the thickness of the epicardial adipose tissue was measured in two regions of the left coronary artery, and the left ventricular morphology, macro/microscopically quantified coronary and valvular atherosclerosis, and weight of the heart were evaluated. Results: This study revealed a higher age in the SCD group (58.82 ± 9.67 vs. 53.4 ± 13.00; p = 0.03), as well as a higher incidence in females (p = 0.03). In terms of heart and coronary artery characteristics, there were higher values of BMI (p = 0.0009), heart weight (p < 0.0001), EAT of the left circumflex artery (LCx) (p < 0.0001), and EAT of the left anterior descending artery (LAD) (p < 0.0001). In the multivariate analysis, a high baseline value of BMI (OR: 4.05; p = 0.004), heart weight (OR: 5.47; p < 0.001), EAT LCx (OR: 23.72; p < 0.001), and EAT LAD (OR: 21.07; p < 0.001) were strong independent predictors of SCD. Moreover, age over 55 years (OR: 2.53; p = 0.045), type Vb plaque (OR: 17.19; p < 0.001), mild valvular atherosclerosis (OR: 4.88; p = 0.002), and moderate left ventricle dilatation (OR: 16.71; p = 0.008) all act as predictors of SCD. Conclusions: The data of this research revealed that higher baseline values of BMI, heart weight, EAT LCx, and EAT LAD highly predict SCD. Furthermore, age above 55 years, type Vb plaque, mild valvular atherosclerosis, and left ventricle dilatation were all risk factors for SCD.

Obesity and sudden cardiac death: Prevalence, pathogenesis, prevention and intervention

Obesity and sudden cardiac death (SCD) share common risk factors. Obesity, in and of itself, can result in the development of SCD. Numerous epidemiologic and clinical studies have demonstrated the close relationships between obesity and SCD, however, the underlying mechanisms remain incompletely understood. Various evidences support the significance of excess adiposity in determining the risk of SCD, including anatomical remodeling, electrical remodeling, metabolic dysfunction, autonomic imbalance. Weight reduction has improved obesity related comorbidities, and reversed abnormal cardiac remodeling. Indeed, it is still unknown whether weight loss contributes to decreased risk of SCD. Further high-quality, prospective trials are needed to strengthen our understanding on weight management and SCD.

Dietary tea seed saponin combined with aerobic exercise attenuated lipid metabolism and oxidative stress in mice fed a high-fat diet (HFD)

Tea seed saponins (TSS) are oleanolane-type pentacyclic triterpenoid saponin mixtures with various pharmacological effects. We aimed to explore the effects of a total of 4 weeks intragastric administration of TSS (140 mg/kg·day) combined with aerobic exercise (AE) on lipid metabolism and its associated oxidative stress in HFD-induced obese mice and to investigate the possible molecular mechanisms. TSS + AE intervention significantly reduced body weight and the adiposity index (including subcutaneous, epididymal, perirenal, and abdominal adipose) in obese mice; improved dyslipidemia by lowering serum TC, TG, and LDL-c levels; and increased HDL-c levels. TSS + AE intervention significantly improved hepatic steatosis by inhibiting lipogenetic Acc, Srebp1c, and Scd1 and upregulating lipolysis genes (Pgc1α, Pgc1β, Pparα, and Cpt1). TSS + AE intervention increased the hepatic protein expression of p-AMPK, SIRT1, and PGC-1α, as well as PPAR-γ and GLUT-4 in skeletal muscle compared with expression in the HFD group. In addition, TSS + AE also modulated oxidative stress in obese mice, which was indicated by the increased serum and liver levels of SOD, GSH, and T-AOC and decreased ROS and MDA levels. These results suggest that TSS + AE intervention can reduce fat accumulation and improve HFD-induced lipid metabolism disorders and oxidative stress. PRACTICAL APPLICATIONS: Obesity is a metabolic disease induced by excess nutritional intake and insufficient energy expenditure. Dietary modifications combined with aerobic exercise are currently an effective method for weight loss. Tea seed saponins (TSS) are a variety of biologically active oleanolane-type pentacyclic triterpenoid saponins that naturally exist in tea seeds. Few articles have focused on the effects and mechanisms of TSS combined with aerobic exercise (AE) in regulating lipid metabolism and improving oxidative damage in vivo. Using an HFD-induced obese mice model to explore the mechanism of TSS + AE in regulating lipid metabolism and its associated oxidative stress damage will help provide reliable data for the application of dietary nutrition combined with AE in anti-obesity.

Metformin Reduces Potassium Currents and Prolongs Repolarization in Non-Diabetic Heart

Metformin is the first choice drug for the treatment of type 2 diabetes due to positive results in reducing hyperglycaemia and insulin resistance. However, diabetic patients have higher risk of ventricular arrhythmia and sudden cardiac death, and metformin failed to reduce ventricular arrhythmia in clinical trials. In order to explore the mechanisms responsible for the lack of protective effect, we investigated in vivo the effect of metformin on cardiac electrical activity in non-diabetic rats; and in vitro in isolated ventricular myocytes, HEK293 cells expressing the hERG channel and human induced pluripotent stem cells derived cardiomyocytes (hIPS-CMs). Surface electrocardiograms showed that long-term metformin treatment (7 weeks) at therapeutic doses prolonged cardiac repolarization, reflected as QT and QTc interval duration, and increased ventricular arrhythmia during the caffeine/dobutamine challenge. Patch-clamp recordings in ventricular myocytes isolated from treated animals showed that the cellular mechanism is a reduction in the cardiac transient outward potassium current (Ito). In vitro, incubation with metformin for 24 h also reduced Ito, prolonged action potential duration, and increased spontaneous contractions in ventricular myocytes isolated from control rats. Metformin incubation also reduced IhERG in HEK293 cells. Finally, metformin incubation prolonged action potential duration at 30% and 90% of repolarization in hIPS-CMs, which is compatible with the reduction of Ito and IhERG. Our results show that metformin directly modifies the electrical behavior of the normal heart. The mechanism consists in the inhibition of repolarizing currents and the subsequent decrease in repolarization capacity, which prolongs AP and QTc duration.