Heart Failure: Causes and Classification

Definition and Classification

Heart failure is a complex clinical syndrome resulting from structural or functional impairment of ventricular filling or ejection of blood, manifesting primarily as dyspnea, fatigue, and fluid retention, as defined by the American College of Cardiology and the American Heart Association 1, 2
The syndrome arises from disorders affecting the pericardium, myocardium, endocardium, heart valves, or great vessels, though most cases stem from impaired left ventricular myocardial function, according to the American College of Cardiology 3, 1

Heart failure with reduced ejection fraction (HFrEF) is characterized by a left ventricular ejection fraction (LVEF) ≤40%, as classified by the European Society of Cardiology 4, 5
Heart failure with preserved ejection fraction (HFpEF) is characterized by an LVEF ≥50%, and is more common in elderly patients, women, and those with hypertension or diabetes, as noted by the European Heart Journal 6

The New York Heart Association (NYHA) functional classification stratifies patients by symptom severity, with Class I indicating no limitation of physical activity and Class IV indicating inability to engage in any physical activity without symptoms, as defined by the American College of Cardiology 1, 3, 4

Ischemic heart disease is the single most common etiology, accounting for approximately 40% of heart failure cases globally, according to the American College of Cardiology 7
Hypertension represents the underlying cause in 17-31% of heart failure cases, with a higher prevalence in HFpEF phenotypes, as noted by the American Heart Association 7
Idiopathic dilated cardiomyopathy accounts for approximately 30% of heart failure cases in European registries, and up to 30% of dilated cardiomyopathy has a genetic cause, as reported by the Journal of the American College of Cardiology 1, 2, 7

Critical geographic differences exist in heart failure etiology, with the highest rates of ischemic etiology in Eastern Europe and the Middle East, and the lowest rates in Africa, as noted by the American College of Cardiology 7

Peripartum cardiomyopathy occurs during pregnancy or postpartum period, with an incidence that varies dramatically by geographic region, as reported by the American Heart Association 7