Persistent left superior vena cava is associated with complex atrial tachyarrhythmias in repaired tetralogy of Fallot: evidence for a right-sided arrhythmogenic substrate

Atrial fibrillation (AF) is an important late complication in patients with repaired tetralogy of Fallot (TOF); however, its clinical determinants and arrhythmogenic substrates remain uncertain. Identifying high-risk anatomical profiles is essential for optimal rhythm management and tailored ablation strategies. We retrospectively analyzed 137 consecutive patients with repaired TOF followed at the University of Tsukuba Hospital (2013–2024). Clinical characteristics, echocardiographic parameters, and procedural findings were compared between patients with and without AF. Logistic regression identified independent predictors. Catheter ablation approaches and outcomes were evaluated in patients who underwent AF ablation. AF occurred in 14 patients (10.2%), frequently coexisting with atrial tachycardia (78.6%). Compared with patients without AF, those with AF were older, had undergone more repeat cardiac surgeries, and more commonly exhibited a persistent left superior vena cava (PLSVC), greater biatrial enlargement, and mildly reduced right ventricular function. On multivariable analysis, PLSVC remained statistically associated with AF (odds ratio 15.5, p = 0.002); however, this association was primarily driven by patients with combined AF and AT, as no PLSVC was observed in the small isolated AF subgroup. Among six patients who underwent catheter ablation, those without PLSVC were successfully treated with pulmonary vein isolation (PVI) alone, whereas two patients with PLSVC underwent right-sided ablation targeting the right atrium and coronary sinus, with no AF recurrence observed during follow-up. PLSVC was associated with more complex atrial tachyarrhythmias, particularly in patients with concomitant AF and AT. Recognizing this substrate may inform individualized ablation strategies beyond conventional PVI.