What is the correlation between Time Of Flight (TOF) and time of reversibility?

From the Guidelines

The time of flight (TOF) in patients with Tetralogy of Fallot (TOF) is associated with a risk of sudden cardiac death (SCD), with an incidence of 2% per decade and approaching 10% by 35 years after surgical repair, as reported in the 2015 study by the American Heart Association 1.

Key Findings

• The risk of SCD in patients with TOF is higher in those with older age at time of repair, advanced RV dilation, presence of RVOT patch, QRS interval ≥180 ms, and annual increase in QRS duration.
• Electrophysiological testing with programmed ventricular stimulation has shown promise in distinguishing high- and low-risk patients, but is currently reserved for patients with rapid palpitations, dizziness, unexplained syncope, or significant Holter findings.
• The 2019 guidelines for the management of adults with congenital heart disease recommend that patients with TOF undergo regular monitoring and follow-up with an ACHD cardiologist to assess their risk of SCD and other complications 1.

Clinical Implications

• Patients with TOF should be monitored regularly for signs and symptoms of SCD, such as syncope, palpitations, and shortness of breath.
• Electrophysiological testing and other diagnostic procedures should be performed in a hospital with cardiologists, anesthesiologists, surgeons, and other providers with expertise in the management of patients with ACHD.
• The optimal timing for pulmonary valve replacement in asymptomatic patients with TOF is still unclear, but it is recommended that patients undergo regular monitoring and follow-up to assess their risk of SCD and other complications.

Recommendations

• Patients with TOF should undergo regular monitoring and follow-up with an ACHD cardiologist to assess their risk of SCD and other complications.
• Electrophysiological testing and other diagnostic procedures should be performed in a hospital with cardiologists, anesthesiologists, surgeons, and other providers with expertise in the management of patients with ACHD.
• Patients with TOF should be educated on the signs and symptoms of SCD and the importance of regular monitoring and follow-up.

From the Research

Time of Reversibility in Tetralogy of Fallot

• The optimal timing of pulmonary valve replacement in patients with Tetralogy of Fallot (ToF) is challenging due to the poorly understood biological mechanisms underlying right ventricular dysfunction 2.
• Determining the optimal timing of interventions is crucial to prevent irreversible right ventricular dysfunction, which can occur due to longstanding pulmonary regurgitation and/or stenosis 2.
• Early postoperative beta-blockers have been associated with improved cardiac output after late complete repair of ToF, suggesting that timing of interventions can impact outcomes 3.
• The risk of complications after surgical repair of ToF in adults is influenced by factors such as older age, longer cardiopulmonary bypass time, right ventricular systolic dysfunction, and history of initial palliative surgery 4.
• Computed tomography (CT) plays a role in the pre- and postoperative evaluation of ToF, helping to assess associated anomalies and identify surgical complications 5.
• The degree of right ventricular outflow tract obstruction (RVOT) is a key factor in determining the pathophysiologic effects of ToF and influencing intra-operative anesthetic management 6.