Tetralogy of Fallot (Repaired) — Adult Management
Definition
Tetralogy of Fallot (TOF) is one of the most common forms of congenital heart disease. The classic anatomy consists of: (1) large VSD, (2) aorta overriding the VSD, (3) right ventricular outflow tract (RVOT) obstruction, and (4) right ventricular hypertrophy. Following surgical repair (typically in infancy), adults with repaired TOF require lifelong surveillance for hemodynamic sequelae, arrhythmias, and risk of sudden cardiac death (SCD).
Key Concepts
RVOT Dysfunction After Repair
- Most common physiological sequela is RVOT dysfunction: pulmonary regurgitation (PR), pulmonary stenosis, or mixed
- Moderate PR defined as CMR-measured regurgitant fraction ≥25%
- Moderate pulmonary stenosis defined as RV systolic pressure ≥2/3 systemic due to RVOT obstruction
- Transannular patch repair → large dyskinetic/aneurysmal RV free wall; fibrotic scar
- Other sequelae: residual VSDs, tricuspid regurgitation, LV dysfunction (up to 20% of adults with TOF), aortic root dilation
- At least 15% born with TOF have pulmonary atresia and required RV-to-PA conduit — conduit replacement needed with time
sources/ACHD-AHA-2025 — very high
Surveillance Imaging
- Echocardiography (COR 1, B-NR): Assess pulmonary and tricuspid valve dysfunction, right atrial size, ventricular size and function, residual VSDs, RVSP estimation
- CMR imaging (COR 1, B-NR): Gold standard for quantifying PR, ventricular volumes and function, PA anatomy and flow, branch PA stenosis, ventricular fibrosis (LGE)
- Normal function + ≤mild PR: CMR every 3–5 years
- Ventricular dysfunction or ≥moderate PR: CMR every 2–3 years
- Cardiac CT (COR 1, B-NR): Required for assessment of coronary artery compression risk before transcatheter PVR (balloon-expandable platform); required for native RVOT anatomy before self-expanding transcatheter PVR
sources/ACHD-AHA-2025 — very high
Pulmonary Valve Replacement (PVR) Criteria
Symptomatic (COR 1, B-NR):
- Moderate or greater pulmonary valve dysfunction + symptoms → PVR recommended
Asymptomatic (COR 2a, B-NR) — requires moderate/greater PR PLUS ≥2 of the following 5:
- RV end-systolic volume index (RVESVi) >80 mL/m²
- RV end-diastolic volume ≥2× LV end-diastolic volume
- RV ejection fraction ≤46%
- LV ejection fraction ≤50%
- Progressive decline in exercise capacity
Key 2025 change: Prior guidelines emphasized indexed RVEDV; 2025 shifts emphasis to RVESVi >80 mL/m² as primary threshold, reflecting stronger correlation with outcomes and the fact that mild-moderate RV dilation post-PVR is not associated with adverse outcomes
Progressive ventricular systolic dysfunction (COR 2a, C-LD): PVR reasonable to preserve ventricular function
Progressive functional TR ≥moderate + RV dilation (COR 2b, C-LD): Pulmonary valve intervention may be reasonable to prevent worsening
sources/ACHD-AHA-2025 — very high
SCD Risk Stratification
Established risk factors for sustained monomorphic VT/SCD (Table 32):
- QRS duration ≥180 ms
- Moderate/greater LV or RV dysfunction
- Prior ventriculotomy
- Late age at definitive repair
- Symptomatic non-sustained VT / arrhythmic symptoms
- QRS fragmentation
- Inducible sustained VA at invasive EP study
Published risk scores (Table 33):
| Score | Design | Key Inputs | Annual Event Rate |
|---|---|---|---|
| PREVENTION-ACHD | Case-control (n=783) | CAD, NYHA, SVT, systemic/subpulmonary EF, QRS ≥120, QT dispersion | Score 0–2: <1%; 3: 1–2%; 4: 3–4%; 5: 5–10%; 6: 11–25%; 7: >25% |
| Brompton (UK) | Observational (n=550) | RV LGE extent, LV LGE, RVEF, LVEF, peak VO₂, BNP, akinetic RVOT length, RV pressure | 0–20: 0.20%/yr; 21–39: 0.90%/yr; ≥40: 3.70%/yr |
| PACES | Case-control (n=286) | Surgical era, arrhythmic symptoms, LV/RV dysfunction, RV pressure/volume, age at repair, QRS ≥180, VT | Low (<3), Moderate (3–6), High (7–9), Very High (>9) |
sources/ACHD-AHA-2025 — very high
Arrhythmia Management
- Moderate risk for sustained VT/SCD: Invasive EP evaluation reasonable (COR 2a, B-NR)
- High risk (by risk score or clinical markers): ICD placement reasonable (COR 2a, B-NR)
- ICD + recurrent appropriate therapies for monomorphic VT: Adjunctive catheter ablation reasonable (COR 2a, B-NR) — new 2025 recommendation
- Before PVR (elective): Pre-emptive EP study ± 3D mapping may be considered (COR 2b, C-LD); actionable results in ~25% of patients; ablation more challenging after valve insertion
- Hemodynamically tolerated monomorphic VT with well-defined isthmus: Ablation monotherapy may be considered in lieu of ICD at ACHD EP centres (COR 2b, C-LD)
- Atrial flutter most commonly involves prior atriotomy or tricuspid annulus substrate → catheter ablation effective
- Atrial fibrillation associated with reduced survival in repaired TOF
sources/ACHD-AHA-2025 — very high
Coronary Artery Considerations
- ≥5% of TOF patients have anomalous LAD from RCA → risk for coronary compression during percutaneous PVR
- Pre-intervention coronary assessment mandatory: CT angiography or simultaneous aortography during balloon expansion in RVOT/PA
sources/ACHD-AHA-2025 — very high
Contradictions / Open Questions
- Tricuspid valve intervention at time of surgical PVR: mixed evidence — some studies show improved TR, others show no difference or worsening
- Optimal timing of PVR in asymptomatic patients remains debated; RVEDVI threshold removal may lead to later intervention in some patients who would have qualified previously
- Role of VT ablation as monotherapy (without ICD) in carefully selected patients is investigational and centre-dependent
sources/ACHD-AHA-2025 — very high
Connections
- Related to concepts/ACHD-AP-Classification — TOF is Class II anatomy
- Related to entities/Pulmonary-Hypertension — PH assessment in TOF
- Related to concepts/Late-Gadolinium-Enhancement — LGE extent guides VT substrate localisation and SCD risk
- Related to concepts/TAVI — transcatheter pulmonary valve replacement parallels transcatheter aortic valve technology