What is congestive heart failure (CHF)?

Definition of Congestive Heart Failure

Congestive heart failure (CHF) is a clinical syndrome requiring both symptoms of heart failure (breathlessness, fatigue, or ankle swelling) AND objective evidence of cardiac dysfunction (systolic and/or diastolic) documented by echocardiography at rest. 1, 2

Core Diagnostic Criteria

The diagnosis of CHF requires fulfillment of two mandatory criteria according to the European Society of Cardiology 1:

• Criterion I: Symptoms of heart failure at rest or during exercise, including breathlessness, fatigue, or ankle swelling 1, 2
• Criterion II: Objective evidence of cardiac dysfunction (preferably by echocardiography) demonstrating systolic and/or diastolic abnormalities at rest 1, 2
• Criterion III (supportive): Response to heart failure treatment, though this alone is insufficient for diagnosis 1

Both Criteria I and II must be fulfilled in all cases - symptoms alone or cardiac dysfunction alone do not constitute heart failure. 1

Pathophysiological Basis

CHF results from any structural or functional cardiac disorder that impairs the ventricle's ability to fill with or eject blood adequately. 2, 3, 4

The syndrome can arise from disorders affecting 1, 2:

• Myocardium (most common - coronary artery disease, hypertension, cardiomyopathy) 2, 5, 4
• Valves (stenosis or regurgitation) 1, 2
• Pericardium (constrictive or restrictive disease) 1, 2
• Endocardium (restrictive cardiomyopathy) 1, 2
• Conduction system (arrhythmias) 1, 2

The failing heart triggers compensatory mechanisms including increased cardiac output via the Frank-Starling mechanism, ventricular remodeling, and neurohormonal activation - all of which initially maintain function but ultimately worsen the condition. 4

Classification by Ejection Fraction

The European Society of Cardiology classifies heart failure into three distinct categories based on left ventricular ejection fraction (LVEF) 2:

• Heart Failure with Reduced Ejection Fraction (HFrEF): LVEF <40% 2
• Heart Failure with Mid-Range Ejection Fraction (HFmrEF): LVEF 40-49% 2
• Heart Failure with Preserved Ejection Fraction (HFpEF): LVEF ≥50% 2

Both systolic and diastolic dysfunction typically coexist regardless of ejection fraction category. 1, 2 Diastolic heart failure is more common in elderly patients, women, and those with systolic hypertension and myocardial hypertrophy with fibrosis. 1, 2

Cardinal Clinical Manifestations

Symptoms

The characteristic symptoms include 1, 2:

• Breathlessness (dyspnea) at rest or with exertion, including orthopnea and paroxysmal nocturnal dyspnea 1, 2
• Fatigue and exercise intolerance from low cardiac output, peripheral hypoperfusion, and skeletal muscle deconditioning 1, 6
• Ankle swelling from fluid retention 1, 2

Signs

Common physical examination findings include 2, 7:

• Elevated jugular venous pressure 2
• Pulmonary rales (crackles) - the hallmark lung finding indicating pulmonary congestion 7
• Peripheral edema 2
• Hepatomegaly and hepatojugular reflux 1
• S3 gallop rhythm 7

Important caveat: Symptoms and signs may be difficult to interpret in elderly patients, obese individuals, and women, requiring careful assessment of different modes (effort-related versus nocturnal). 1

Terminology Clarifications

Preferred Nomenclature

The American College of Cardiology prefers the term "heart failure" over "congestive heart failure" because not all patients have volume overload at initial or subsequent evaluations. 2

Descriptive Terms with Limited Clinical Utility

The following terms are descriptive but provide no etiological information and are therefore of limited use in determining modern treatment 1:

• Right versus left heart failure: Refers to predominant congestion of systemic versus pulmonary veins, but does not necessarily indicate which ventricle is most damaged 1
• High-output versus low-output failure 1
• Forward versus backward failure 1
• Congestive, overt, or treated heart failure 1

Severity Classification

Mild, moderate, or severe heart failure describes symptom severity 1:

• Mild: Patients can move around with no important limitations of dyspnea or fatigue 1
• Moderate: Intermediate symptom burden 1
• Severe: Markedly symptomatic patients requiring frequent medical attention 1

The NYHA (New York Heart Association) classification is widely used to categorize functional capacity from Class I (no limitation) to Class IV (symptoms at rest). 1

Critical Diagnostic Principles

Heart failure should never be the only diagnosis - the underlying cause must always be identified to guide specific treatment approaches. 1, 2

The diagnosis is primarily clinical, based on careful history and physical examination, supported by appropriate investigations (particularly echocardiography). 1, 2

A clinical response to treatment alone is insufficient for diagnosis, though patients should generally demonstrate improvement in symptoms and/or signs with appropriate therapy such as diuretics or nitrates. 1

Asymptomatic structural or functional cardiac abnormalities are considered precursors of symptomatic heart failure and are associated with high mortality, warranting identification and treatment. 2

Epidemiology and Prognosis

The prevalence of heart failure is 2-3% in the general population, rising sharply to 10-20% in those aged 70-80 years. 1 CHF affects over 5 million people in the United States and is one of the most common reasons for hospitalization in those aged 65 and over. 3, 4

The prognosis remains poor despite modern therapy: Overall, 50% of patients are dead at 4 years, and 40% of patients admitted to hospital are dead or readmitted within 1 year. 1 The condition carries a 50% 5-year mortality despite significant advances in understanding and treatment. 4