Tetralogy of fallot natural history complications and prognosis

The prognosis of patients with repaired tetralogy of Fallot has improved over the years and these patients now have the potential to lead normal lives. As these patients grow, there may be leakage of the repaired pulmonic valve. There may be a persistent risk of sudden cardiac death.

• If left untreated, the natural history of tetralogy of Fallot results in progressive right ventricular hypertrophy and right ventricular dilatation due to the increased resistance to flow into the pulmonary circuit.
• The dilated cardiomyopathy progresses to right heart failure, usually with accompanying left heart failure.

Common complications of tetralogy of fallot include:^[1][2]

• Delayed growth and development
• Irregular heart rhythms (arrhythmias)
• Seizures as a result of hypoxia
• Stroke and embolic complications such as a brain abscess
• Pulmonary embolism
• Sudden cardiac death: The worse the right ventricle dysfunction, the worse the risk for ventricular tachycardia and sudden death.
• Bacterial endocarditis
• Reoperation for pulmonary stenosis

The survival for unrepaired tetralogy of Fallot is as follows:^[3]

• 75% at one year
• 70% at two years
• 60% at four years
• 50% at six years
• 30% at ten years
• 10% at twenty years
• 5% at forty years

• If pulmonary atresia is present as well, survival is even poorer with only 50% of patients surviving to one year, and only 8% of patients surviving to 10 years.

• Patients with repaired tetralogy of Fallot now have the potential to lead normal lives with continued excellent cardiac function.
• Most survivors are in NYHA Class I heart failure.
• Some patients have more pronounced symptoms with exertion.^[4][5]
• Current techniques for total surgical repair greatly improve the hemodynamic function of the heart with tetralogy of Fallot but do not provide a lifetime correction of the defect.
• Ninety percent of patients with total repair as infants develop a progressively leaky pulmonary valve (pulmonic insufficiency as the heart grows to its adult size. Patients also may have some degree of residual right ventricular outflow obstruction and damage to the conduction system of the heart from surgical corrections, causing conduction abnormalities on the EKG and/or arrhythmias.
• Tetralogy of Fallot patients are at risk for development of heart failure. Therefore, lifetime follow-up care by an adult congenital cardiologist is recommended to assess and monitor these risks and to recommend treatment, such as interventional procedures or re-operation, if it becomes necessary.
• Tetralogy of Fallot patients are at risk for sudden cardiac death with a 1% to 5% lifetime incidence. Risk factors for sudden cardiac death include:

• Older age at repair
• Male sex
• Advanced NY heart association class
• Repair via atriotomy
• Two major electrocardiographic risk factors include complete heart block beyond the third post operative day and QRS duration > 18 milliseconds, and rapid development of QRS prolongation in the first 6 months after repair.

• There is limited data regarding the benefit of automatic implantable cardiac defibrillator (AICD) implantation in these patients.
• Antibiotic prophylaxis is indicated during dental treatment in order to prevent infective endocarditis.

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