Heart Failure Characterization

Core Definition

The European Society of Cardiology defines heart failure as a clinical syndrome characterized by typical symptoms and signs caused by structural and/or functional cardiac abnormality, resulting in reduced cardiac output and/or elevated intracardiac pressures at rest or during stress, in patients with reduced ejection fraction, mid-range ejection fraction, or preserved ejection fraction 1, 2
Heart failure is not equivalent to cardiomyopathy or left ventricular dysfunction, but rather a clinical diagnosis requiring both symptoms/signs and objective cardiac abnormalities, as stated by the American College of Cardiology 3

The American Heart Association recommends classifying heart failure patients by left ventricular ejection fraction (LVEF) into three categories: Heart Failure with Reduced EF (HFrEF): LVEF ≤40%, Heart Failure with Mid-range EF (HFmrEF): LVEF 41-49%, and Heart Failure with Preserved EF (HFpEF): LVEF ≥50% 1, 2
Different phenotypes have distinct underlying etiologies, demographics, comorbidities, and responses to therapies, with only HFrEF having proven mortality-reducing treatments, according to the European Heart Journal 1, 2

The American College of Cardiology recommends a four-stage progression system for heart failure characterization: Stage A (At-Risk), Stage B (Pre-HF), Stage C (Symptomatic HF), and Stage D (Advanced HF) 4, 5
The staging system is progressive, with patients advancing through stages with worsening prognosis, though disease course can be arrested or potentially reversed at any stage, as stated by the Journal of the American College of Radiology 6

The New York Heart Association (NYHA) functional classification provides symptom-based characterization, with four classes: Class I, Class II, Class III, and Class IV, which describe current functional status and can fluctuate 4, 5
The NYHA class describes current functional status, while staging describes structural disease progression and is unidirectional, according to the Journal of the American College of Cardiology 3

Identifying the underlying cause of heart failure is crucial, with common causes including ischemic cardiomyopathy, hypertensive heart disease, idiopathic dilated cardiomyopathy, valvular disease, and other causes, as stated by the European Heart Journal 1, 2
The specific etiology determines specific treatment, such as valve repair for valvular disease or rate control for tachycardia-induced cardiomyopathy, according to the American College of Cardiology 3

Heart failure characterization requires integration of multiple data elements, including clinical assessment, biomarkers, cardiac imaging, and laboratory tests, as recommended by the European Heart Journal 1, 2
Elevated natriuretic peptides (BNP or NT-proBNP) are essential for diagnosis confirmation, and echocardiography is the primary modality for assessing ventricular function and identifying structural abnormalities, according to the Journal of the American College of Radiology 6

Advanced characterization may include cardiopulmonary exercise testing (CPET), exercise stress echocardiography, and invasive hemodynamics to identify disease trajectories and risk factors, especially in early or preserved ejection fraction phenotypes, as stated by the Journal of the American College of Cardiology 12