The Mechanisms of Atrial Pathoelectrophysiology in Hypertrophic Cardiomyopathy (MAP-HCM) study aims to define the electrophysiological mechanisms underlying atrial arrhythmias in patients with hypertrophic cardiomyopathy. The study focuses on detailed electroanatomical mapping and invasive electrophysiological measurements obtained during atrial fibrillation ablation procedures to characterise voltage, conduction velocity and restitution. Direct left atrial pressure measurements are performed to assess the haemodynamic contribution to atrial remodelling. These data are complemented by atrial cardiac MRI to assess atrial remodelling. The multimodal dataset will be integrated with clinical information and used to develop patient specific computational models, improving understanding of atrial cardiomyopathy and informing more personalised approaches to arrhythmia management in this cohort.