• Clinical science

Congestive heart failure

Summary

Congestive heart failure (CHF) is a clinical condition in which the heart is unable to pump enough blood to meet the metabolic needs of the body because of pathological changes in the myocardium. The three main causes of CHF are coronary heart disease, diabetes mellitus, and hypertension. These conditions cause ventricular dysfunction with low cardiac output, which results in blood congestion (backward failure) and poor systemic perfusion (forward failure). CHF is classified as either left heart failure (LHF) or right heart failure (RHF), although biventricular (global) CHF is most commonly seen in clinical practice. LHF leads to pulmonary edema and resulting dyspnea, while RHF induces systemic venous congestion that causes symptoms such as pitting edema, jugular venous distension, and hepatomegaly. Biventricular CHF manifests with clinical features of both RHF and LHF, as well as general symptoms such as tachycardia, fatigue, and nocturia. In rare cases, high-output CHF may occur as a result of conditions that increase cardiac output and thereby overwhelm the heart. Acute decompensated heart failure (ADHF) may occur as an exacerbation of CHF or be caused by an acute cardiac condition such as myocardial infarction. CHF is diagnosed based on clinical presentation and requires an initial workup to assess disease severity and possible causes. Initial workup includes measurement of brain natriuretic peptide levels, chest x-ray, and an ECG. Management of CHF includes lifestyle modifications and treatment of associated conditions (e.g., hypertension) and comorbidities (e.g., anemia), along with pharmacologic agents that reduce the workload of the heart. ADHF requires hospitalization and more intensive measures, such as hemodialysis.

Definition

References:[1]

Epidemiology

  • Prevalence
    • 1–2% of the population (∼ 5.7 million individuals) in the US has CHF.
      • The incidence is higher among African Americans, Hispanics, and Native Americans.
    • Increases with age: ∼ 10% of individuals > 60 years old are affected.
    • Systolic heart disease is the most common form of CHF overall.

References:[2][3]

Epidemiological data refers to the US, unless otherwise specified.

Etiology

Systolic dysfunction (reduced EF)

Diastolic dysfunction (preserved EF)

General causes
Specific causes
Further risk factors

The three major causes of heart failure are coronary artery disease, hypertension, and diabetes mellitus. Patients typically have multiple risk factors that contribute to the development of CHF.

References:[4][5][2][3][6][7]

Pathophysiology

Cardiac output, which is stroke volume times heart rate, is determined by three factors: preload, afterload, and ventricular contractility.

Underlying mechanism of reduced cardiac output

  1. Systolic ventricular dysfunction (most common) due to:
    • Reduced contractility: Damage and loss of myocytes reduce ventricular contractility and stroke volume.
    • Increased afterload: increase in mean aortic pressure, outflow obstruction
    • Increased preload: ventricular volume overload
    • Cardiac arrhythmias
    • High-output conditions (see “High-output heart failure” below)
  2. Diastolic ventricular dysfunction due to:
    • Decreased ventricular compliance: increased stiffness or impaired relaxation of the ventricle → reduced ventricular filling and increased diastolic pressure → decreased cardiac output
    • Increased afterload; : increase in pulmonary artery pressure
    • Increased preload; : ventricular volume overload

Consequences of systolic and diastolic dysfunction

Compensation mechanisms

CHF is characterized by reduced cardiac output that results in venous congestion and poor systemic perfusion!

References:[4][8]

Clinical features

General features of heart failure

Clinical features of left-sided heart failure

Clinical features of right-sided heart failure

Pulmonary symptoms dominate Symptoms of fluid retention (backward failure) dominate

In clinical practice, biventricular heart failure with features of left and right heart failure is more likely than isolated failure of one ventricle!

References:[4][5][11][12][13][14]

Subtypes and variants

High-output heart failure

References:[5][15][2][16]

Stages

NYHA functional classification

The NYHA (New York Heart Association) functional classification system is used to assess the patient's functional capacities (i.e., limitations of physical activity and symptoms) and has prognostic value.

NYHA class Characteristics
Class I

No limitations of physical activity; no symptoms of CHF

Class II Slight limitations of moderate or prolonged physical activity (e.g., symptoms after climbing 2 flights of stairs or heavy lifting); comfortable at rest
Class III Marked limitations of physical activity (symptoms during daily activities like dressing, walking across rooms); comfortable only at rest
Class IV Confined to bed, discomfort during any form of physical activity; symptoms present at rest

American Heart Association (AHA) Classification (2013)

The AHA classification system classifies patients according to their stage of disease. It takes objective findings (patient history, diagnostic findings) as well as symptoms of CHF into account.

Stages Objective assessment Corresponding NYHA functional class
Stage A

High risk of developing heart failure (e.g., pre-existing arterial hypertension, CAD, diabetes mellitus); no structural cardiac changes

No corresponding NYHA class
Stage B Structural damage to the heart (e.g., infarct scars, dilatation, hypertrophy), without signs or symptoms of heart failure NYHA I
Stage C Structural damage to the heart + signs or symptoms of heart failure NYHA I, II, III, IV
Stage D Heart failure at its terminal stage NYHA IV

References:[11][17][18][19][20][21]

Diagnostics

Heart failure is primarily a clinical diagnosis. Laboratory tests and imaging tests, including a chest x-ray and echocardiogram, are useful for evaluating the severity and cause of the condition.

Diagnostic approach [22]

  1. Medical history, including pre-existing conditions and history of alcohol and recreational or prescribed drug use
  2. Initial evaluation involves a range of routine laboratory tests and a test for BNP level, ECG, and chest x-ray.
  3. Echocardiography is the gold standard tool for assessing cardiac morphology and function, as well as investigating the underlying cause of CHF.
  4. Other procedures (exercise testing, angiography) may be required for further investigation.

Initial evaluation [22]

Laboratory analysis

  • Elevated BNP and NT-pro BNP
    • High levels of BNP in patients with classic symptoms of CHF confirm the diagnosis (high predictive index). [23]
CHF unlikely CHF likely
BNP (pg/mL) < 100 > 500
NT-pro BNP (pg/mL) < 300

> 450

Electrocardiogram (ECG)

Chest x-ray

  • Useful diagnostic tool to evaluate a patient with dyspnea and differentiate CHF from pulmonary disease
  • Signs of cardiomegaly
    • Cardiac-to-thoracic width ratio > 0.5
    • Boot-shaped heart on PA view (due to left ventricular enlargement)
  • Assess pulmonary congestion (see x-ray findings in pulmonary congestion)

Transthoracic echocardiogram

  • Gold standard for evaluating patients with heart failure
  • Assess ventricular function and hemodynamics
    • Atrial and ventricular size
    • Interventricular septum thickness: > 11 mm (normal 6–11 mm) indicates cardiac hypertrophy
    • Systolic function: left ventricular ejection fraction
      • Normal EF: > 55%
      • Reduced EF: 30–44%
      • Extremely reduced EF: < 30%
    • Diastolic function (diastolic filling, ventricle dilation)
  • Investigate etiology

Further tests

References:[4][11][2][24][12][25][26][27][28]

Treatment

General measures [22]

  • Lifestyle modifications
  • Patient education
    • Self-monitoring and symptom recognition
    • Daily weight check
      • Weight gain > 2 kg within 3 days: consult the doctor
    • Monitoring of potential side effects (e.g., hypotension caused by ACE inhibitors, hyperkalemia caused by aldosterone-antagonists, sensitivity to sunlight caused by amiodarone)
  • Treat any underlying conditions and contributing comorbidities.

Pharmacologic treatment algorithm

Drug NYHA stages Indications Contraindications and important side effects Benefits
I II III IV
First-line drugs
Diuretics (loop diuretics and thiazide diuretics) (✓) (✓)
  • Monitor for hypokalemia and hyponatremia, weight gain, and volume status
  • Improve symptoms
ACE inhibitors
  • Monitor for hyperkalemia, hypotension, creatinine (renal impairment)
  • Improve symptoms and prognosis
Beta blockers (✓)
Aldosterone antagonists (✓)
  • Monitor for hyperkalemia
Second-line drugs
Ivabradine (✓) (✓) (✓)
  • If the highest tolerable dose of beta blocker is reached and the patient is still symptomatic or if the patient has a contraindication to beta-blocker use
  • If EF < 35% and the patient has a sinus rhythm with a resting heart rate > 70/min
  • Contraindicated in severe bradycardia
  • Improves symptoms
  • Reduces hospitalization rate
Hydralazine plus nitrate (✓) (✓)
  • If EF < 40%; particularly beneficial for African-American patients
  • Alternative if ACE inhibitors and AT1 blockers are not tolerated
  • Monitor for volume depletion and hypotension
  • Improves symptoms; may improve prognosis

Digoxin

(✓) (✓) (✓)
  • Improves symptoms
  • Reduces hospitalization rate
ARNI (angiotensin receptor-neprilysin inhibitor) (✓) (✓) (✓) (✓)
  • Persistent or worsening symptoms despite adequate treatment regimen with first-line drugs
  • Administered as combination valsartan-sacubitril
  • Improves prognosis
  • Reduces hospitalization rate
Nesiritide (BNP derivative)

(✓): see “Indications” column for detailed information

Drugs that improve prognosis: beta blockers, ACE inhibitors, and aldosterone antagonists!

Drugs that improve symptoms: diuretics and digoxin (significantly reduce the number of hospitalizations)!

Conducting regular blood tests to assess electrolyte levels (potassium and sodium) is mandatory if the patient is on diuretics!

Contraindicated drugs

Invasive procedures

References:[2][29][17][30][31][32][33][34]

Complications

We list the most important complications. The selection is not exhaustive.

Acute decompensated heart failure

Cardiac decompensation is the most common reason for hospital admissions and is the most important complication of congestive heart failure.

Etiology

ADHF typically occurs in patients who have a history of CHF or other cardiac conditions in which an acute cause precipitates the deterioration of cardiac function.

Clinical features

  • Rapid exacerbation of symptoms of CHF (see symptoms of left heart failure and symptoms of right heart failure)
  • Pulmonary congestion with:
    • Acute, severe dyspnea and orthopnea; worse when supine
    • Cough (occasionally with frothing, blood-tinged sputum)
    • Cyanosis
    • Auscultation of the lungs: rales accompanied by wheezing
    • Flash pulmonary edema: rapid, life-threatening accumulation of fluid associated with the risk of acute respiratory distress
  • Weakness, fatigue, and cold, clammy skin

Diagnostics

The radiologic signs of pulmonary congestion can be remembered with “ABCDE”: A = Alveolar edema (bat's wings), B = Kerley B lines (interstitial edema), C = Cardiomegaly, D = Dilated prominent pulmonary vessels, and E= Effusions!

Differential diagnosis of pulmonary edema and respiratory distress

Treatment

Beta blockers must be used cautiously in decompensated heart failure!

Management of ADHF can be remembered with “LMNOP”: L = Lasix (furosemide), M = Morphine, N = Nitrates, O= Oxygen, P = Position (with elevated upper body).
References:[4][5][5][11][35][2][36][37][38][39]

Cardiorenal syndrome

Cardiorenal syndrome is a complication of acute heart failure and CHF.

  • Definition: : a complex syndrome in which renal function progressively declines as a result of severe cardiac dysfunction; occurs in ∼ 20–30% of cases of ADHF
  • Pathophysiology
  • Diagnosis: GFR, creatinine that cannot be explained by underlying kidney disease
  • Treatment: treat heart failure; manage renal failure (see treatment of acute renal injury)
  • Prognosis: : CHF with reduced GFR is associated with a poor prognosis.

References:[40][41][42]

Prognosis

  • The prognosis depends on the patient, type and severity of heart disease, medication regimens, and lifestyle changes.
  • The prognosis for patients with preserved EF is similar to or better than for patients with decreased EF
  • Risk stratification scales may be used to evaluate the prognosis (e.g., CHARM and CORONA risk scores).
  • Factors associated with worse prognosis
  • 1-year survival according to NYHA stage
    • Stage I: ∼ 95%
    • Stage II: ∼ 85%
    • Stage III: ∼ 85%
    • Stage IV: ∼ 35%

References:[20]