This editorial refers to ‘Contemporary Predictors of Death and Sustained Ventricular Tachycardia in Patients With Repaired Tetralogy of Fallot Enrolled in the INDICATOR Cohort’ by Valente et al.1

Challenge of risk stratification

Tetralogy of Fallot (ToF) is the most common cyanotic heart defect at birth. Major advances in cardiac surgery and paediatric cardiology now enable the vast majority of patients born with this condition to survive to adulthood. However, surgical repair cannot cure these patients and life expectancy continues to be compromised. Haemodynamically relevant pulmonary regurgitation (PR) is common and appears to have a major impact on long-term morbidity and mortality. It causes RV volume overload eventually associated with RV dysfunction and is—in itself—associated with life-threatening arrhythmias and sudden cardiac death. While timely pulmonary valve replacement may help to avoid some of the long-term complications associated with PR,2 it appears that merely replacing the pulmonary valve is not sufficient to avoid sudden death in this young population.3 As a consequence, numerous researchers have been struggling to identify reliable risk predictors in ToF patients over the last decades. This is not an easy undertaking: the heterogeneity of the condition combined with the relatively low annual mortality rate requires large patient cohorts and considerable follow-up periods to ensure sufficient statistical power. In addition, not all patients die suddenly and information on the cause of death is not always available. Not surprisingly, the number of risk predictors remains therefore limited (for an overview of studies, see table 1): the most prominent and widely used one is QRS prolongation …