Atrial myopathy in persistent atrial fibrillation: three-dimensional quantification of atrial fibrosis by high-density electro-anatomic mapping and its association with arrhythmia duration

Background Progressive atrial myopathy marked by fibrotic remodelling drives the transition from paroxysmal to persistent atrial fibrillation (AF), yet the temporal dynamics of fibrosis within persistent AF remain poorly defined. Objective To quantify dense scar and borderline fibrotic zones using high-density electro-anatomic mapping (HD-EAM) in patients with persistent AF, and to compare fibrotic burden between early persistent (>7 days–<3 months) and persistent (≥3 months–<1 year) AF. Methods Retrospectively analysed 78 consecutive patients (59 ± 15 years, 59% men) undergoing first-time pulmonary vein isolation for persistent AF. Atrial voltage maps (CARTO 3 CONFIDENSE™) acquired in sinus rhythm classified tissue as healthy (>0.5 mV), borderline (0.3–0.5 mV), or dense scar (<0.2 mV). Echocardiographic left atrial diameter (LAD) and volume (LAV) were compared with mapping data. The primary endpoint was dense scar point count; secondary endpoints included AF/atrial tachycardia recurrence and correlation between imaging modalities. Results Twenty-two patients had early persistent and 56 persistent AF. Mapping resolution was similar (5 193 ± 459 vs 5 399 ± 601 points, p = 0.83). Dense scar points were significantly higher in persistent AF (2 807 ± 336 vs 1 634 ± 236; p < 0.001). LAD and LAV from HD-EAM correlated moderately with echocardiography (r = 0.45 and 0.48; both p < 0.01) but did not differ between groups. After 7.2 ± 3.7 months, recurrence occurred in 16% of persistent versus 8% of early persistent AF (p = 0.11). Conclusions Fibrotic burden increases markedly after three months of uninterrupted AF despite stable atrial size. HD-EAM enables intra-procedural quantification of atrial myopathy and may guide personalised ablation strategies.