ABSTRACT
DEFINITION There is no universally accepted definition of heart failure. There are two conceptual approaches: (1) primarily subjective: a clinical syndrome characterized by symptoms (especially breathlessness) and signs of fluid retention caused by cardiac dysfunction or (2) primarily objective: cardiac dysfunction leading to activation of compensatory mechanisms and a reduction in exercise capacity. Patients who fulfill the subjective definition should also fulfill the objective criteria but the reverse is often not true (i.e. patients may have severe but asymptomatic cardiac dysfunction). An ejection fraction (EF) <40% is commonly used as a threshold for defining left ventricular systolic dysfunction (LVSD) but there are many other forms of cardiac dysfunction that may lead to symptoms of heart failure or to premature death.
