Journal of the American Heart Association, Volume 15, Issue 6 , March 17, 2026. BackgroundThrombotic events, including acute ischemic stroke, are more common in individuals with congenital heart disease (CHD). Whether common thrombophilia variants contribute to thrombotic risk in this population remains unclear. We evaluated whether prothrombin G20210A (F2c.97G>A) and factor V Leiden (F5c.1601G>A; p.Arg534Gln) are associated with thrombotic events in CHD.MethodsParticipants in the Pediatric Cardiac Genomics Consortium with exome sequencing and electronic medical record data were identified. Individuals were stratified by prothrombin G20210A and factor V Leiden genotypes, ventricular physiology, and antithrombotic therapy. The primary outcome was the presence ofInternational Classification of Diseases(ICD) or Phecodes (phenotype codes) for thrombotic events.ResultsAmong 4008 participants (median age, 11.4 [interquartile range, 5.1–17.9] years; 44.4% boys), thrombotic events occurred in 737 (18%), including 93 (13%) with acute ischemic stroke. Compared with the Genome Aggregation Database, the CHD cohort had a lower prevalence of heterozygous prothrombin G20210A and factor V Leiden variants. Variant prevalence did not differ between participants with and without thrombotic events.
Journal of the American Heart Association, Volume 15, Issue 6 , March 17, 2026. BackgroundThrombotic events, including acute ischemic stroke, are more common in individuals with congenital heart disease (CHD). Whether common thrombophilia variants contribute to thrombotic risk in this population remains unclear. We evaluated whether prothrombin G20210A (F2c.97G>A) and factor V Leiden (F5c.1601G>A; p.Arg534Gln) are associated with thrombotic events in CHD.MethodsParticipants in the Pediatric Cardiac Genomics Consortium with exome sequencing and electronic medical record data were identified. Individuals were stratified by prothrombin G20210A and factor V Leiden genotypes, ventricular physiology, and antithrombotic therapy. The primary outcome was the presence ofInternational Classification of Diseases(ICD) or Phecodes (phenotype codes) for thrombotic events.ResultsAmong 4008 participants (median age, 11.4 [interquartile range, 5.1–17.9] years; 44.4% boys), thrombotic events occurred in 737 (18%), including 93 (13%) with acute ischemic stroke. Compared with the Genome Aggregation Database, the CHD cohort had a lower prevalence of heterozygous prothrombin G20210A and factor V Leiden variants. Variant prevalence did not differ between participants with and without thrombotic events. Single‐ventricle CHD was associated with higher thrombosis frequency than biventricular CHD (35% versus 16%,P≤0.0001), without differences in variant prevalence.ConclusionsIn this multicenter CHD cohort, prothrombin G20210A and factor V Leiden were not significantly associated with thrombotic outcomes, supporting recommendations against routine screening. Given low variant prevalence, the study was powered to exclude only large associations. Reduced variant frequency suggests survivorship bias beginning in fetal life. Larger integrated clinical–genomic studies are needed to refine thrombotic risk stratification in CHD.RegistrationURL:https://www.clinicaltrials.gov; Unique Identifier: NCT03347214.