What is the difference between cardiomyopathy and heart failure?

Difference Between Cardiomyopathy and Heart Failure

Cardiomyopathy is a structural or functional disorder of the heart muscle, while heart failure is a clinical syndrome characterized by specific symptoms and signs resulting from cardiac dysfunction.

Key Distinctions

Cardiomyopathy

• Definition: A disease of the heart muscle that affects structure and function
• Classification:
  • Primary (genetic, mixed, or acquired) affecting only the heart
  • Secondary (resulting from systemic conditions)
  • Phenotypes include dilated, hypertrophic, restrictive, and others 1
• Pathophysiology: Structural abnormality of the myocardium
• Diagnosis: Based on imaging findings showing abnormal heart structure/function
• Examples:
  • Dilated cardiomyopathy (DCM): ventricular dilation with depressed function
  • Hypertrophic cardiomyopathy: ventricular hypertrophy
  • Restrictive cardiomyopathy: impaired ventricular filling
  • Arrhythmogenic right ventricular cardiomyopathy

Heart Failure

• Definition: A clinical syndrome resulting from any cardiac disorder that impairs ventricular filling or ejection 1
• Manifestations: Dyspnea, fatigue, fluid retention, pulmonary congestion, peripheral edema
• Classification:
  • Based on ejection fraction: HFrEF (reduced) or HFpEF (preserved)
  • Based on symptoms: NYHA Class I-IV
  • Based on stages: A through D (risk to end-stage) 1
• Diagnosis: Clinical diagnosis based on symptoms and signs
• Causes: Can result from cardiomyopathy but also from other conditions like coronary artery disease, hypertension, valvular disease

Relationship Between the Two

Cardiomyopathy can lead to heart failure, but not all cardiomyopathies cause heart failure, and not all heart failure is caused by cardiomyopathy. As stated in the ACC/AHA guidelines: "It should be emphasized that HF is not equivalent to cardiomyopathy or to LV dysfunction; these latter terms describe possible structural or functional reasons for the development of HF." 1

Clinical Implications

Diagnostic Approach

• Cardiomyopathy: Primarily diagnosed through imaging (echocardiography, cardiac MRI)
• Heart Failure: Diagnosed through clinical evaluation of symptoms and signs

Treatment Considerations

• Cardiomyopathy: Treatment targets the specific type and underlying cause

  • Dilated cardiomyopathy may require standard heart failure therapy
  • Hypertrophic cardiomyopathy may need specific management for outflow obstruction
  • Some cardiomyopathies have specific treatments (enzyme replacement, immunotherapy) 2

• Heart Failure: Treatment focuses on symptom relief, disease progression, and mortality reduction

  • Stage-based approach from risk factor modification to advanced therapies
  • Medications target neurohormonal activation and hemodynamic abnormalities

Common Pitfalls

1. Terminology confusion: Using "cardiomyopathy" and "heart failure" interchangeably is incorrect
2. Diagnostic oversight: Focusing only on heart structure (cardiomyopathy) without assessing clinical syndrome (heart failure)
3. Treatment mismatch: Treating the structural disease without addressing the clinical syndrome
4. Prognostic assessment: Some cardiomyopathies may exist without heart failure symptoms but still carry risk

Clinical Algorithm

1. Assess for symptoms and signs of heart failure (dyspnea, fatigue, edema)
2. Evaluate cardiac structure and function (imaging)
3. Determine:
   • If abnormal cardiac structure/function exists → possible cardiomyopathy
   • If clinical syndrome of heart failure exists → heart failure
   • If both exist → cardiomyopathy leading to heart failure
4. Identify specific type of cardiomyopathy if present
5. Stage heart failure if present (A-D and NYHA class)
6. Develop treatment plan addressing both structural disease and clinical syndrome

Remember that cardiomyopathy represents the structural/functional heart muscle disorder, while heart failure represents the clinical manifestation of cardiac dysfunction, regardless of cause.