Mechanistic Relevance of Ventricular Arrhythmias in Heart Failure with Preserved Ejection Fraction.

Heart failure with preserved ejection fraction (HFpEF) is increasing at an alarming rate worldwide, with limited effective therapeutic interventions in patients. Sudden cardiac death (SCD) and ventricular arrhythmias present substantial risks for the prognosis of these patients. Obesity is a risk factor for HFpEF and life-threatening arrhythmias. Obesity and its associated metabolic dysregulation, leading to metabolic syndrome, are an epidemic that poses a significant public health problem. More than one-third of the world population is overweight or obese, leading to an enhanced risk of incidence and mortality due to cardiovascular disease (CVD). Obesity predisposes patients to atrial fibrillation and ventricular and supraventricular arrhythmias-conditions that are caused by dysfunction in the electrical activity of the heart. To date, current therapeutic options for the cardiomyopathy of obesity are limited, suggesting that there is considerable room for the development of therapeutic interventions with novel mechanisms of action that will help normalize sinus rhythms in obese patients. Emerging candidates for modulation by obesity are cardiac ion channels and Ca-handling proteins. However, the underlying molecular mechanisms of the impact of obesity on these channels and Ca-handling proteins remain incompletely understood. Obesity is marked by the accumulation of adipose tissue, which is associated with a variety of adverse adaptations, including dyslipidemia (or abnormal systemic levels of free fatty acids), increased secretion of proinflammatory cytokines, fibrosis, hyperglycemia, and insulin resistance, which cause electrical remodeling and, thus, predispose patients to arrhythmias. Furthermore, adipose tissue is also associated with the accumulation of subcutaneous and visceral fat, which is marked by distinct signaling mechanisms. Thus, there may also be functional differences in the effects of the regional distribution of fat deposits on ion channel/Ca-handling protein expression. Evaluating alterations in their functional expression in obesity will lead to progress in the knowledge of the mechanisms responsible for obesity-related arrhythmias. These advances are likely to reveal new targets for pharmacological modulation. Understanding how obesity and related mechanisms lead to cardiac electrical remodeling is likely to have a significant medical and economic impact. Nevertheless, substantial knowledge gaps remain regarding HFpEF treatment, requiring further investigations to identify potential therapeutic targets. The objective of this study is to review cardiac ion channel/Ca-handling protein remodeling in the predisposition to metabolic HFpEF and arrhythmias. This review further highlights interleukin-6 (IL-6) as a potential target, cardiac bridging integrator 1 (cBIN1) as a promising gene therapy agent, and leukotriene B4 (LTB4) as an underappreciated pathway in future HFpEF management.