Types of Ebstein Anomaly
Ebstein anomaly is not formally classified into distinct "types" but rather exists as a spectrum of anatomic severity ranging from mild tricuspid valve abnormalities to severe right heart malformation. 1
Understanding the Spectrum of Disease
Rather than discrete categories, Ebstein anomaly encompasses a wide spectrum of anatomic and functional abnormalities with infinite variety in the combinations and severity of involved structures. 2 The American College of Cardiology describes this as a continuum of pathology affecting the tricuspid valve and right ventricle, where the clinical presentation depends on the extent of tricuspid valve leaflet distortion, right heart size, degree of tricuspid regurgitation, and presence of right-to-left shunting. 1
Anatomic Features That Define Severity
The severity spectrum is characterized by varying degrees of the following core anatomic features: 1, 3
- Apical displacement of the septal and posterior tricuspid valve leaflets below the atrioventricular junction into the right ventricle
- Adherence of tricuspid valve leaflets to the underlying myocardium (failure of delamination)
- Atrialization and dilation of the right ventricular inflow portion
- Redundancy, tethering, and fenestrations of the anterior tricuspid valve leaflet
- Tricuspid regurgitation severity (from mild to severe)
- Right atrial enlargement magnitude
Clinical Presentation-Based Severity Stratification
Physiological Staging System
The American Heart Association recognizes a physiological staging approach for follow-up and management: 3
- Stage A (Mild): Minimal symptoms, requiring cardiology visits every 12-24 months
- Stage B (Moderate): Moderate symptoms, requiring evaluation every 12 months
- Stage C (Severe): Significant symptoms, requiring evaluation every 6-12 months
- Stage D (End-stage): Advanced disease, requiring evaluation every 3-6 months
Age-Based Presentation Patterns
The spectrum manifests differently based on age at presentation: 1
Neonatal presentation (most severe): Cardiomegaly, congestive heart failure, and cyanosis with 20-40% mortality within the first month and less than 50% survival to 5 years. 1
Pediatric/adolescent presentation (moderate): Progressive right-sided heart failure with electrophysiological symptoms more common than hemodynamic issues after age 10 years. 1
Adult presentation (mild to moderate): Exercise intolerance, dyspnea, fatigue, symptomatic arrhythmias, or completely asymptomatic with survival to the ninth decade reported. 1
Associated Abnormalities That Modify Severity
More than 50% of patients have atrial-level shunting (patent foramen ovale or atrial septal defect) causing varying degrees of cyanosis. 1, 3 Approximately 25% have accessory conduction pathways increasing arrhythmia risk. 1, 3 Additional findings include ventricular septal defects, right ventricular outflow tract obstruction, mitral valve prolapse, and left ventricular dysfunction. 1, 3
Prognostic Indicators of Severity
Poor prognostic factors that define more severe disease include: 1
- NYHA functional class III or IV symptoms
- Cardiothoracic ratio greater than 65%
- Atrial fibrillation
- Severe cyanosis
- Magnitude of tricuspid regurgitation
The 10-year survival for patients presenting in the perinatal period is approximately 61%, while those reaching late adolescence and adulthood often have excellent outcomes. 1, 4