Left Atrial Strain and History of Life-Threatening Arrhythmia in Adults with Repaired Tetralogy of Fallot: A Cardiovascular Magnetic Resonance Study.

Risk stratification for ventricular arrhythmia in adults with repaired tetralogy of Fallot (r-ToF) remains suboptimal. We investigated the relationships between left atrial reservoir strain (LAS) measured by cardiovascular magnetic resonance (CMR) and history of life-threatening ventricular arrhythmia (h-LTA) in r-ToF. We retrospectively analyzed 39 adults with r-ToF (mean age 39 ± 15 years; 69% male) undergoing routine CMR. LAS was quantified from four-chamber cine images. Patients with h-LTA, defined as a documented episode of any ventricular tachyarrhythmia, namely non-sustained ventricular tachycardia (≥ 3 consecutive ventricular beats for ≤ 30 s duration), sustained ventricular tachycardia (lasting ≥ 30 s), or ventricular fibrillation, were compared with those without. Ten patients (26%) had h-LTA. They tended to be older (46 ± 17 vs. 39 ± 13 years; p = 0.06), had longer QRS duration (167 ± 19 vs. 142 ± 25 ms; p < 0.001), and more often prior pulmonary valve replacement (40% vs. 24%; p = 0.03). LAS was significantly lower in the h-LTA group (12.9 ± 4.0% vs. 17.9 ± 4.6%; p = 0.01), while other ventricular and atrial indices, as well as late gadolinium enhancement, showed no difference. LAS correlated inversely with QRS duration (r = - 0.43; p = 0.005) and showed the strongest association with h-LTA (AUC = 0.838). Reproducibility for LAS was good (ICC = 0.84-0.97). In our study, CMR-derived LAS was markedly reduced in r-ToF patients with h-LTA. LAS demonstrated better discriminative performance in identifying patients with h-LTA. LAS may be a promising marker for arrhythmic risk stratification in r-ToF, complementing established CMR criteria, and warrants validation in larger prospective studies.