1. Introduction Heart failure (HF) is a complex clinical syndrome that results from either functional or structural impairment of ventricles identified by the presence of current or prior characteristic symptoms, such as breathlessness, ankle swelling, and fatigue. In the U.S., prevalent cases of HF now exceed 5.8 million, and each year, more than 550,000 new cases are diagnosed [1]. Furthermore, studies have suggested that the prevalence of HF is increasing with age [2].
