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Heart Failure: A Comprehensive Overview

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1. Definition

• The AHA/ACC/HFSA guideline defines HF as symptoms and signs that result from any structural or functional impairment of ventricular filling or ejection.
• The ESC definition emphasizes cardinal symptoms (breathlessness, ankle swelling, fatigue) accompanied by signs (elevated JVP, pulmonary crackles, peripheral edema) due to structural/functional cardiac abnormality resulting in elevated intracardiac pressures and/or inadequate cardiac output at rest or during exercise.
• A universal definition (Bozkurt et al., 2021) defines HF as: symptoms and/or signs caused by a structural and/or functional cardiac abnormality, corroborated by elevated natriuretic peptides or objective evidence of pulmonary/systemic congestion.
• In pathophysiologic terms: elevated cardiac filling pressures and/or inadequate peripheral oxygen delivery at rest or during stress, caused by cardiac dysfunction.
• The term "heart failure" is preferred over the older "congestive heart failure" because some patients present without volume overload signs.

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2. Classification

A. By Ejection Fraction (EF)

B. By ACC/AHA Staging (Progression Model)

C. NYHA Functional Classification (Symptom Severity)

D. By Onset

• Acute HF: Rapid onset or worsening; ~20% are new-onset (ACS, acute valve dysfunction, hypertensive urgency)
• Chronic HF: Longstanding symptoms managed with medical/device therapy; at risk for decompensation
• Acute pulmonary edema: Severe elevation of pulmonary capillary wedge pressure; pink frothy sputum

E. Other Descriptors

• Left-sided vs. right-sided (or biventricular)
• High-output HF: CO is normal or elevated but insufficient for metabolic demands (e.g., thyrotoxicosis, AV fistula, severe anemia, beriberi)
• Low-output HF: Most common; reduced CO with elevated SVR

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3. Etiology

Primary (Myocardial) Causes

Precipitating Factors for Decompensation (in known HF)

• Medication non-adherence or dietary indiscretion (excess salt/fluid)
• Infection (pneumonia - increases metabolic demand)
• Arrhythmia (new atrial fibrillation is a major precipitant)
• Uncontrolled hypertension
• Pulmonary embolism
• Myocardial ischemia/infarction
• Renal failure
• Anemia
• Drugs (NSAIDs, negative inotropes, excessive IV fluids)
• Thyroid dysfunction

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4. Pathophysiology (Brief Overview)

1. Neurohormonal activation: Sympathetic nervous system (↑ norepinephrine), RAAS (↑ angiotensin II, aldosterone), and ADH → sodium/water retention, vasoconstriction
2. Ventricular remodeling: Chamber dilation, wall thinning, spherical geometry, mitral regurgitation - initially compensatory, ultimately maladaptive
3. Cardiorenal syndrome: Venous congestion (not just reduced forward flow) impairs renal perfusion → worsens fluid retention
4. Systemic inflammation: Gut congestion → increased intestinal permeability → bacterial LPS → TNF-α, IL-1, IL-6 → progressive myocardial dysfunction and cardiac cachexia
5. Skeletal muscle changes: Reduced blood flow, endothelial dysfunction, metabolic myopathy → fatigue and exercise intolerance

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5. Clinical Features

Symptoms

• Dyspnea on exertion - earliest and most common symptom
• Orthopnea - breathlessness on lying flat; relieved by sitting up; occurs within 1-2 min of recumbency
• Paroxysmal nocturnal dyspnea (PND) - awakens patient from sleep, requires sitting upright for ~30 min; may be accompanied by cough/wheeze ("cardiac asthma")
• Acute pulmonary edema - severe breathlessness, pink frothy sputum, Cheyne-Stokes respiration
• Fatigue and weakness - due to reduced CO and skeletal muscle changes
• Dry or productive cough (pulmonary congestion)

• Peripheral edema (dependent, pitting; bilateral leg edema)
• Weight gain
• Abdominal bloating, anorexia, early satiety, nausea (bowel wall edema, hepatic congestion)
• Right upper quadrant pain (hepatic capsule distension)
• Ascites and anasarca in advanced disease

• Fatigue, weakness at rest
• Mental dullness, confusion (in elderly with cerebrovascular disease)
• Cool peripheries, narrow pulse pressure

• Mood disturbance, depression (independent risk factor for adverse outcomes)
• Nocturia
• Cardiac cachexia in advanced disease

Physical Signs

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6. Diagnosis

Clinical Criteria

Investigations

• Not specific; may show: LVH, ST-T changes, Q waves (prior MI), LBBB, AF
• A normal ECG has high negative predictive value for HFrEF

• Cardiomegaly (CTR > 0.5)
• Pulmonary venous congestion: upper lobe blood diversion ("bat-wing" pattern)
• Kerley B lines (interstitial edema), alveolar edema, pleural effusions
• Hilar haze ("bat's wing" pattern in acute pulmonary edema)

• Assesses LV/RV size and function, LVEF, wall motion abnormalities
• Diastolic function assessment (E/A ratio, tissue Doppler, E/e')
• Valvular disease, pericardial disease
• Guides classification (HFrEF vs HFpEF)

• BNP / NT-proBNP: Elevated in HF; excellent negative predictive value; levels correlate with severity and prognosis. NT-proBNP >125 pg/mL (chronic) or >300 pg/mL (acute) is diagnostic cut-off per ESC guidelines
• Troponin: Elevated in acute decompensation or ischemic etiology
• High-sensitivity CRP, uric acid: Markers of inflammation and prognosis

• CBC: Anemia (common comorbidity, worsens HF)
• BMP/CMP: Renal function (cardiorenal syndrome), electrolytes, liver enzymes (hepatic congestion)
• Thyroid function (hyperthyroidism/hypothyroidism)
• Fasting glucose, HbA1c (diabetes comorbidity)
• Iron studies (iron deficiency is common, treatable)

• Cardiac MRI: Gold standard for myocardial fibrosis (late gadolinium enhancement), cardiomyopathy characterization
• Nuclear imaging: Viability assessment, sarcoidosis
• Coronary angiography / CT coronary angiography: For suspected ischemic etiology

• Pulmonary artery catheterization (Swan-Ganz): PCWP > 18 mmHg confirms elevated filling pressures; useful in refractory/complex HF

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7. Management

General / Non-pharmacological Measures (All Stages)

• Dietary sodium restriction: < 2-3 g/day; fluid restriction in hyponatremia
• Daily weight monitoring: Alert for > 2 kg gain in 2 days
• Exercise training: Improves functional capacity and quality of life in stable HFrEF
• Treat modifiable risk factors: Hypertension, diabetes, dyslipidemia, obesity, smoking cessation
• Vaccination: Annual influenza, pneumococcal vaccines
• Avoid harmful drugs: NSAIDs, most CCBs (except amlodipine/felodipine in HFrEF), TZDs, cocaine

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HFrEF (EF < 40%) - Pharmacological Treatment

1. Renin-Angiotensin-Aldosterone System (RAAS) Blockade

• ACE inhibitors (e.g., enalapril, lisinopril, ramipril): Reduce afterload/preload; reduce mortality, hospitalization, reverse remodeling. First-line in all symptomatic HFrEF
• ARBs (e.g., valsartan, candesartan): Alternative if ACE inhibitor-intolerant (cough/angioedema)
• Sacubitril/valsartan (ARNI): Angiotensin receptor-neprilysin inhibitor; superior to enalapril in PARADIGM-HF trial; recommended as replacement for ACE inhibitor/ARB in eligible patients (NYHA II-IV, ambulatory)

2. Beta-Blockers

• Carvedilol, metoprolol succinate (CR/XL), bisoprolol
• Counter maladaptive sympathetic activation; reduce sudden cardiac death and all-cause mortality
• Start low, titrate slowly; avoid in decompensated HF

3. Mineralocorticoid Receptor Antagonists (MRAs)

• Spironolactone, eplerenone
• Reduce aldosterone-mediated fibrosis and fluid retention
• Proven mortality benefit in NYHA III-IV HFrEF (RALES) and post-MI HFrEF (EPHESUS)
• Monitor potassium and renal function

4. SGLT-2 Inhibitors

• Dapagliflozin, empagliflozin
• Originally developed for diabetes; dramatic reduction in HF hospitalizations and CV death
• DAPA-HF and EMPEROR-Reduced trials: benefit regardless of diabetes status
• Mechanism: natriuresis, weight loss, cardiorenal protection, improved mitochondrial function
• Now recommended for all HFrEF patients (NYHA II-IV)

Additional Pharmacotherapy

• Diuretics (loop diuretics: furosemide, torsemide): Essential for symptom relief (congestion); no proven mortality benefit; titrate to euvolemia
• Ivabradine: HR-lowering in sinus rhythm, HR ≥ 70 bpm on max beta-blocker; reduces HF hospitalizations (SHIFT trial)
• Hydralazine + isosorbide dinitrate: Vasodilator combination; benefit in self-identified Black patients (A-HeFT trial); alternative if RAAS blockers not tolerated
• Vericiguat: Soluble guanylate cyclase stimulator; reduces HF hospitalizations in worsening HFrEF (VICTORIA trial)
• Digoxin: Reduces HF hospitalizations but no mortality benefit (DIG trial); used for rate control in AF or refractory symptoms; narrow therapeutic index
• Intravenous iron (ferric carboxymaltose): Improves symptoms and exercise capacity in iron-deficient HFrEF regardless of anemia

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Device Therapy in HFrEF

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HFpEF (EF ≥ 50%) - Management

• SGLT-2 inhibitors (empagliflozin, dapagliflozin): Now recommended in HFpEF; EMPEROR-Preserved and DELIVER trials showed reduction in HF hospitalizations
• Diuretics: For symptom relief of congestion
• Treat underlying comorbidities: Hypertension (strict BP control), AF (rate/rhythm control), obesity, diabetes, sleep apnea
• MRAs: Spironolactone showed possible benefit in HFpEF (TOPCAT trial) particularly in Americas subgroup
• GLP-1 agonists (semaglutide): Emerging evidence for benefit in HFpEF with obesity (SELECT trial)

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Acute Decompensated Heart Failure (ADHF)

• LMNOP mnemonic: Lasix (furosemide IV), Morphine (reduces preload/anxiolysis - controversial), Nitrates (IV nitroglycerin for preload reduction, especially hypertensive), Oxygen, Position (upright)
• IV loop diuretics (furosemide): Cornerstone; aim for 0.5-1 mL/kg/hr urine output
• Vasodilators (IV nitroglycerin, nesiritide): In hypertensive pulmonary edema
• Inotropes (dobutamine, milrinone): In cardiogenic shock / severe low output; bridge to definitive therapy
• Vasopressors (norepinephrine): In cardiogenic shock with hypotension
• Ultrafiltration: For diuretic-resistant congestion
• Ventilatory support: Non-invasive positive pressure ventilation (CPAP/BiPAP) for acute pulmonary edema; intubation for refractory cases
• Start/continue GDMT: SGLT-2 inhibitors initiated during hospitalization show benefit (DAPA-ACT HF-TIMI 68 trial, 2025)

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Recent Updates (2025)

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Summary Algorithm for HFrEF Management

Confirmed HFrEF (EF <40%)
        ↓
Start GDMT ("Fantastic Four"):
  1. ARNI (sacubitril/valsartan) or ACEi/ARB
  2. Beta-blocker (carvedilol/metoprolol succinate/bisoprolol)
  3. MRA (spironolactone/eplerenone)
  4. SGLT-2 inhibitor (dapagliflozin/empagliflozin)
        ↓
Add loop diuretic if congestion present
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Consider ivabradine (HR ≥70, sinus rhythm)
Consider iron replacement if iron deficient
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Reassess EF at 3-6 months
  EF ≤35%: Consider ICD / CRT if QRS ≥150ms LBBB
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Stage D (refractory): LVAD, transplant evaluation

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Prognosis

• Overall 5-year mortality approaches 50%, similar to many cancers
• Annual mortality in NYHA Class IV: ~50-75%
• Improved significantly with modern GDMT (ARNI + BB + MRA + SGLT2i can reduce mortality by ~50% vs. placebo)
• Major causes of death: sudden cardiac death (arrhythmia) and progressive pump failure

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• Harrison's Principles of Internal Medicine 22E (2025), Chapters 264-265
• Goldman-Cecil Medicine, International Edition, Chapter 46
• Fuster and Hurst's The Heart, 15th Edition, Chapter 48
• Braunwald's Heart Disease, 11th Edition
• Bozkurt et al. Universal Definition and Classification of Heart Failure. J Card Fail 2021
• DAPA ACT HF-TIMI 68, Circulation 2025 PMID: 40884036