Early atrial remodelling drives arrhythmia in Fabry Disease

Background: Fabry disease (FD) is an X-linked lysosomal storage disorder caused by α-galactosidase A (α-Gal A) deficiency, resulting in multi-organ accumulation of sphingolipid, namely globotriaosylceramide (Gb3). This triggers ventricular myocardial hypertrophy, fibrosis, and inflammation, driving arrhythmia and sudden death, a common cause of FD mortality. Atrial fibrillation (AF) is common in FD, yet the cellular mechanisms accounting for this are unknown. To address this, we conducted electrocardiography (ECG) analysis from a large cohort of adults with FD at varying stages of cardiomyopathy. Cellular contractile and electrophysiological function were examined in an atrial FD model, developed using gene-edited atrial cardiomyocytes and imputed into in-silico atrial models to provide insight into arrhythmia mechanisms. Methods: In 115 adults with FD, ECG P-wave characteristics were compared with non-FD controls. Induced pluripotent stem cells (iPSCs) were genome-edited using CRISPR-Cas9 to introduce the GLA p. N215S variant and differentiated into atrial cardiomyocytes (iPSC-CMs). Contraction, calcium handling and electrophysiology experiments were conducted to explore proarrhythmic mechanisms. A bi-atrial in-silico model was developed with the cellular changes induced by GLA p. N215S iPSC-CMs. Results: ECG analysis demonstrated P-wave duration and PQ interval shortening in FD adults before onset of cardiomyopathy on imaging and biochemical criteria. FD patients exhibited a higher incidence of premature atrial contractions and increased risk of developing AF. In our cellular model, GLA p. N215S iPSC-CMs were deficient in α-Gal A and exhibited Gb3 accumulation. Atrial GLA p. N215S iPSC-CMs demonstrated a more positive diastolic membrane potential, faster action potential upstroke velocity, greater burden of delayed afterdepolarizations, greater contraction force, slower beat rate and dysfunction in calcium handling compared to wildtype iPSC-CMs. Inputting these changes into the in-silico model resulted in similar P-wave morphology changes to those seen in early FD cardiomyopathy and increased the action potential duration (APD) restitution slope, causing APD alternans and