Heart failure with reduced ejection fraction.

Heart failure is a global public health problem that affects more than 26 million people worldwide. The global burden of heart failure is growing and is expected to increase substantially with the ageing of the population. Heart failure with reduced ejection fraction accounts for approximately 50% of all cases of heart failure in the United States and is associated with substantial morbidity and reduced quality of life. Several diseases, such as myocardial infarction, certain infectious diseases and endocrine disorders, can initiate a primary pathophysiological process that can lead to reduced ventricular function and to heart failure. Initially, ventricular impairment is compensated for by the activation of the sympathetic nervous system and the renin-angiotensin-aldosterone system, but chronic activation of these pathways leads to worsening cardiac function. The symptoms of heart failure can be associated with other conditions and include dyspnoea, fatigue, limitations in exercise tolerance and fluid accumulation, which can make diagnosis difficult. Management strategies include the use of pharmacological therapies and implantable devices to regulate cardiac function. Despite these available treatments, heart failure remains incurable, and patients have a poor prognosis and high mortality rate. Consequently, the development of new therapies is imperative and requires further research.