Is fatigue at rest an important indicator in heart failure management?

Fatigue in Heart Failure: Clinical Significance and Assessment

Fatigue is a cardinal manifestation of heart failure, alongside dyspnea, and is considered an essential symptom in the clinical diagnosis and management of heart failure. 1

Definition and Pathophysiology

• Fatigue in heart failure is a complex symptom with origins in both physiological and psychological factors, including low cardiac output, peripheral hypoperfusion, and skeletal muscle deconditioning 1
• The origins of fatigue are multifaceted, making it challenging to quantify and assess clinically 1, 2
• Fatigue results from changes in peripheral muscle metabolism secondary to decreased vasodilative capacity and physical inactivity 3

Clinical Significance

• Fatigue is one of the cardinal manifestations of heart failure, alongside dyspnea, and is explicitly defined as such in major heart failure guidelines 1
• The symptom is characterized by both general fatigue (lacking strength and energy) and exertional fatigue (worsening with physical activity) 4
• Fatigue may limit exercise tolerance and significantly impair the functional capacity and quality of life of affected individuals 1, 2
• Clinically documented fatigue is found in approximately 39% of newly diagnosed heart failure patients 5

Presentation Patterns

• Fatigue may present independently of fluid retention - some patients have exercise intolerance with little evidence of fluid retention, while others primarily complain of edema with few symptoms of fatigue 1
• Fatigue can manifest at different levels of exertion, which forms the basis of the NYHA classification system:
  • Class I: No fatigue with ordinary physical activity 1
  • Class II: Fatigue occurs with ordinary physical activity 1
  • Class III: Fatigue occurs with less than ordinary activity 1
  • Class IV: Fatigue present even at rest 1

Relationship to Heart Failure Severity

• There is a poor relationship between symptoms (including fatigue) and the severity of cardiac dysfunction 1, 2
• Patients with preserved ejection fraction may have severe symptoms while those with reduced ejection fraction may be relatively asymptomatic 2
• The New York Heart Association (NYHA) functional classification uses fatigue as a key symptom to classify heart failure severity, but this is subjective and can fluctuate over time 1
• Recent research has identified distinct fatigue subtypes in heart failure patients, with most patients experiencing concordant levels of general and exertional fatigue 4

Assessment and Management

• Fatigue should be assessed as part of the initial diagnostic workup for heart failure and during follow-up evaluations 2
• Depression has demonstrated the strongest association with fatigue in heart failure patients 5
• Fatigue is often part of a symptom cluster, alongside dyspnea, chest pain, edema, syncope, and palpitations 5
• Management approaches should target underlying causes:
  • Increase peripheral perfusion through vasodilator therapy 3
  • Encourage appropriate physical activity to combat deconditioning 3, 6
  • Address psychological factors, particularly depression 5
  • Consider restorative activities that are involuntarily attentive, socially interactive, and mentally absorbing 6

Clinical Pitfalls

• Relying solely on the presence or absence of fatigue at rest is insufficient for heart failure diagnosis or management 1
• Fatigue may be attributed to beta-blocker therapy, but other causes should be considered, including sleep apnea, overdiuresis, or depression 1
• The severity of symptoms may fluctuate even without changes in medications, making consistent assessment challenging 1
• Fatigue may develop slowly over weeks or months despite hemodynamic improvements from therapy 1

Prognostic Implications

• Studies show conflicting evidence regarding the prognostic implications of fatigue in heart failure 7
• Recent research suggests that while fatigue may provide a prognostic signal in the short term, this is largely explained by physiologic confounders 5

In conclusion, while fatigue at rest can be present in heart failure patients with severe disease (NYHA Class IV), it is not a requirement for diagnosis. Fatigue at various levels of exertion is more commonly observed and clinically significant for diagnosis and management of heart failure.