Heart Failure Classification NYHA

Heart Failure Classification

• Heart failure can be classified based on the New York Heart Association (NYHA) functional classification system, which has four classes:

  • Class I: Comfortable at rest, but ordinary physical activity causes symptoms of HF
  • Class II: Slightly limited by symptoms of HF during ordinary activity
  • Class III: Markedly limited by symptoms of HF during less-than-ordinary activity
  • Class IV: Unable to carry on any physical activity without symptoms of HF, or symptoms of HF at rest

• Heart failure can also be classified based on left ventricular ejection fraction (LVEF):

  • HFrEF (HF with reduced EF): LVEF ≤40%
  • HFimpEF (HF with improved EF): Previous LVEF ≤40% and a follow-up measurement of LVEF >40%
  • HFmrEF (HF with mildly reduced EF): LVEF 41%–49% and evidence of spontaneous or provokable increased LV filling pressures
  • HFpEF (HF with preserved EF): LVEF ≥50% and evidence of spontaneous or provokable increased LV filling pressures

Causes of Heart Failure

• Common causes of heart failure:
  • Coronary artery diseases
  • Hypertensive heart diseases
  • Cardiomyopathy (dilated, hypertrophic, restrictive)
  • Valvular heart diseases
  • Constrictive pericarditis
  • High output heart failure (e.g. chronic anemia, thyrotoxicosis, atrioventricular shunt)
  • Cardiac dysrhythmia and heart block

Etiologies

• Heart failure can result from any disorder that affects the ability of the heart to contract (systolic function) and/or relax (diastolic dysfunction):
  • Ischemic heart disease (50-60% of cases)
  • Hypertension (30-40% of patients)
  • Idiopathic dilated cardiomyopathy (5-10% of patients)
  • Other cardiomyopathies (e.g. alcoholic, viral, hypertrophic)
  • Drug-induced

Prognosis

• The prognosis of heart failure is poor, with factors affecting prognosis including age, gender, LVEF, renal function, blood pressure, heart failure etiology, and drug or device therapy
• The 5-year mortality rate is 50%, and the median survival following onset is 1.7 years for men and 3.2 years for women

Pathophysiological Changes

• Compensatory mechanisms:
  • Dilation of the heart to increase stroke volume
  • Increased sympathetic drive to increase cardiac output
  • Activation of the renin-angiotensin system, leading to secondary hyperaldosteronism with retention of sodium and water
• Myocardial hypertrophy: an intrinsic compensatory mechanism to maintain cardiac performance, but can lead to ischemic changes, impairment of diastolic filling, and alteration of ventricular geometry

Natriuretic Peptides

• Natriuretic peptides play a significant role in water and salt homeostasis, providing counter-regulatory balance to the neurohumoral pathways
• The natriuretic peptide system consists of three main peptides: atrial natriuretic peptide (ANP), B-type natriuretic peptide (BNP), and C-type natriuretic peptide (CNP)
• Elevated circulating levels of natriuretic peptides are found in patients with chronic heart failure, and assessment of BNP (or its inactive N-terminal fragment, NT-proBNP) is a key component of the diagnostic pathway for patients with suspected heart failure

Symptoms and Signs

• Volume overload and congestion: orthopnea, pulmonary crackles, edema, ascites, hepatojugular reflux, hepatomegaly, engorged neck veins, dyspnea, tachypnea, cough
• Cardiac: enlargement, gallop, tachycardia
• General: limitation of activity, inability of concentration, nocturia, anorexia, nausea, bloating

Laboratory Tests

• BNP > 35 pg/mL for ambulatory patients or > 100 pg/mL for patients hospitalized or with decompensated HF
• NT-proBNP >125 pg/mL for ambulatory patients or > 300 pg/mL for patients hospitalized or with decompensated HF
• Electrocardiogram may be normal or show numerous abnormalities
• Serum creatinine may be increased due to hypoperfusion
• Complete blood count is useful to determine if HF is due to reduced oxygen-carrying capacity
• Chest x-ray: useful for detection of cardiac enlargement, pulmonary edema, and pleural effusions
• Echocardiogram: used to assess LV size, valve function, pericardial effusion, wall motion abnormalities, and ejection fraction