Congestive heart failure

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Congestive Heart Failure (CHF)

Definition

Heart failure is a clinical syndrome resulting from the inability of the heart to meet the metabolic requirements of the body at normal filling pressures. The term "congestive heart failure" is historically common, but modern guidelines prefer simply "heart failure" because pulmonary congestion may actually be absent in many patients who present with dyspnea and reduced exercise capacity alone.

Textbook of Family Medicine, 9e
Braunwald's Heart Disease, 2 Vol Set

Types

Type	EF	Primary Defect
HFrEF (HF with reduced EF)	< 45-50%	Impaired LV systolic contraction
HFpEF (HF with preserved EF)	> 45-50%	Impaired LV filling/relaxation (diastolic dysfunction)

HFpEF and HFrEF are nearly equally prevalent. The distinction matters because most mortality-reducing drug therapies are proven specifically for HFrEF.

Classification

ACC/AHA Stages vs. NYHA Functional Classes

ACC/AHA Stage	Description	NYHA Class
A	High risk, no structural disease, no symptoms	None
B	Structural heart disease, no symptoms	I
C	Structural disease + current/prior symptoms	I, II, or III
D	Refractory HF requiring specialized intervention	IV

NYHA Classes:

Class I - No limitation; ordinary activity causes no symptoms
Class II - Slight limitation; comfortable at rest, but ordinary activity causes symptoms
Class III - Marked limitation; comfortable at rest, but less-than-ordinary activity causes symptoms
Class IV - Unable to carry on any activity without symptoms; symptoms present at rest
Braunwald's Heart Disease, Table 48.1

Pathophysiology

The hemodynamic model of HF has been replaced by the concept of LV remodeling - progressive LV dilation and dysfunction driven by neurohormonal activation.

Key neurohormonal pathways:

RAAS activation - Angiotensin II causes myocyte apoptosis, hypertrophy, and fibrosis. Aldosterone augments these effects and "escapes" ACE inhibition, requiring additional aldosterone blockade.
Sympathetic nervous system (SNS) activation - Elevated catecholamines cause vasoconstriction, sodium retention, direct myocardial toxicity, and downregulation of beta-adrenergic receptors.
Endothelin-1 - Released by dysfunctional endothelium; potent vasoconstrictor.
Inflammatory cytokines - Further worsen endothelial dysfunction.
Matrix metalloproteinases (MMPs) - Drive cardiac fibrosis and collagen deposition.
Calcium handling abnormalities and metabolic shift from fatty acid oxidation to glycolysis.

Pharmacologic interventions that block neurohormonal activation are the cornerstone of therapy and reduce mortality.

Textbook of Family Medicine, 9e
Goldman-Cecil Medicine

Common precipitating causes of LV remodeling: CAD/MI, hypertension, valvular heart disease, diabetes, congenital heart defects, anemia, alcoholism, viral myocarditis, HIV, Chagas disease, cardiotoxic substances.

Clinical Features

Symptoms

Pulmonary congestion (left-sided HF): Dyspnea on exertion, orthopnea, paroxysmal nocturnal dyspnea (PND), tachypnea, cough, fatigue, diminished exercise capacity
Systemic congestion (right-sided HF): Peripheral edema, weight gain, increasing abdominal girth, right upper quadrant pain (hepatic congestion), early satiety, nocturia
Low cardiac output: Fatigue, somnolence, diminished mental acuity, unintentional weight loss/cachexia

Important notes:

Dyspnea at rest carries high diagnostic sensitivity and poor prognosis
PND is one of the most reliable indicators of HF
Cheyne-Stokes respiration indicates advanced HF with low cardiac output and poor prognosis
Patients may hide symptoms by reducing activity - probe exercise capacity directly
Braunwald's Heart Disease, Table 48.2

Diagnosis

The evaluation is guided by history and physical examination. Key workup includes:

ECG - Assess for ischemia, hypertrophy, arrhythmia (AF is present in 10-50% depending on NYHA class)
Echocardiogram - Establishes EF, identifies HFrEF vs HFpEF, valvular disease, wall motion abnormalities
BNP / NT-proBNP - Elevated in HF; useful for diagnosis and monitoring
Chest X-ray - Cardiomegaly, pulmonary vascular congestion, pleural effusions
Labs - CBC (anemia), CMP (renal function, electrolytes), TSH, urinalysis

Treatment: HFrEF (Evidence-Based Pharmacotherapy)

Modern guidelines support four pillars of therapy for HFrEF (NYHA Class II-IV):

1. ARNI (Sacubitril/Valsartan) - preferred over ACE inhibitor

Neprilysin inhibitor + ARB combination. Neprilysin breaks down natriuretic peptides; inhibiting it augments vasodilation and natriuresis. Must not be combined with an ACE inhibitor (risk of angioedema). Use if the patient can tolerate it as first-line over ACE inhibitor/ARB alone.

2. ACE Inhibitor or ARB (if ARNI not tolerated)

Reduce LV size, improve EF, reduce symptoms/hospitalizations, and prolong survival
Recommended for all patients with LV systolic dysfunction, regardless of symptoms
ARBs preferred if ACE inhibitor causes cough (~5%) or angioedema
Do not combine ACE inhibitor + ARB (increased side effects, no added benefit)
"Start low, go slow" with dose up-titration; monitor BP, renal function, potassium

3. Beta-Blocker

Counteract sympathetic overactivation; reduce heart rate, prevent arrhythmias, reverse remodeling
Reduce mortality by ~27% in sinus rhythm patients
Approved agents: carvedilol, metoprolol succinate, bisoprolol
Contraindications: asthma, 2nd/3rd degree AV block
Do not initiate during acute decompensated HF - wait until stabilized

4. Mineralocorticoid Receptor Antagonist (MRA) - spironolactone / eplerenone

Block aldosterone "escape" from ACE inhibition
Reduce fibrosis and adverse remodeling
Monitor for hyperkalemia and renal function

5. SGLT2 Inhibitor (dapagliflozin / empagliflozin) - now a 5th pillar

Reduce hospitalization and cardiovascular death in HFrEF (and increasingly in HFpEF)
A 2025 meta-analysis (DAPA ACT HF-TIMI 68, PMID 40884036) confirmed benefit of dapagliflozin even in patients hospitalized for HF

6. Diuretics (symptomatic relief - no mortality benefit)

Loop diuretics (furosemide, bumetanide) for fluid overload
Do not substitute for neurohormonal blockers, but are needed for congestion control
ACE inhibitors mitigate diuretic-induced hypokalemia

7. Digoxin

Modest benefit for symptom control and reducing hospitalizations; no mortality benefit
Rate control in AF with HFrEF alongside beta-blockers
Goldman-Cecil Medicine; Textbook of Family Medicine, 9e; Braunwald's Heart Disease

Device Therapy

ICD - For primary prevention of sudden cardiac death in patients with LVEF ≤35% on optimal medical therapy for ≥3 months
CRT (Cardiac Resynchronization Therapy) - For LBBB with QRS ≥150 ms and LVEF ≤35%; improves LVEF, symptoms, and survival; can be combined with ICD (CRT-D)

Heart Failure and Atrial Fibrillation

AF is present in 10% of NYHA Class I patients and up to 50% in Class IV. It worsens HF through rapid/irregular ventricular rates and loss of AV synchrony.

Rate control: beta-blockers (preferred in HFrEF), digoxin; non-DHP calcium channel blockers only if HFpEF
Rhythm control: only amiodarone or dofetilide are safe in HFrEF (other antiarrhythmics increase mortality)
AF catheter ablation in HF patients: meta-analyses show improved LVEF, quality of life, and reduced mortality vs. medical therapy alone (CASTLE-AF trial)
Braunwald's Heart Disease

Prognosis

Mortality remains ~50% within 5 years of diagnosis
1-month rehospitalization rate is approximately 25%
Cheyne-Stokes respiration, unintentional weight loss/cachexia, and NYHA Class IV are markers of poor prognosis

Key Points Summary

Concept	Key Fact
Preferred term	"Heart failure" (not CHF, since congestion may be absent)
Primary mechanism	Neurohormonal activation → LV remodeling
Two main types	HFrEF (EF <45%) vs HFpEF (EF >45%)
Mortality-reducing drugs (HFrEF)	ARNI > ACE-I/ARB + beta-blocker + MRA + SGLT2i
Drugs for symptom relief only	Diuretics, digoxin
ARNI + ACE-I	Contraindicated (angioedema risk)
Device therapy threshold	ICD if LVEF ≤35%; CRT if LVEF ≤35% + LBBB
AF rate control in HFrEF	Beta-blockers + digoxin

Recent evidence update: A 2025 RCT + meta-analysis (PMID 40884036) in Circulation confirmed dapagliflozin reduces adverse outcomes even when started in patients actively hospitalized for acute HF - supporting early in-hospital initiation of SGLT2 inhibitors.

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