New Research PaperRelationship Between Fibrosis Detected on Late Gadolinium-Enhanced CMR and Re-Entrant Activity Assessed With ECGI in Human Persistent Atrial Fibrillation

OBJECTIVES This study sought to assess the relationship between fibrosis and re-entrant activity in persistent atrial fibrillation (AF).BACKGROUND The mechanisms involved in sustaining re-entrant activity during AF are poorly understood.METHODS Forty-one patients with persistent AF (age 56 +/- 12 years; 6 women) were evaluated. High-resolution electrocardiographic imaging (ECGI) was performed during AF by using a 252-chest electrode array, and phase mapping was applied to locate re-entrant activity. Sites of high re-entrant activity were defined as re-entrant regions. Late gadolinium-enhanced (LGE) cardiac magnetic resonance (CMR) was performed at 1.25 +/- 1.25 +/- 2.5 mm resolution to characterize atrial fibrosis and measure atrial volumes. The relationship between LGE burden and the number of re-entrant regions was analyzed. Local LGE density was computed and characterized at re-entrant sites. All patients underwent catheter ablation targeting re-entrant regions, the procedural endpoint being AF termination. Clinical, CMR, and ECGI predictors of acute procedural success were then analyzed.RESULTS Left atrial (LA) LGE burden was 22.1 +/- 5.9% of the wall, and LA volume was 74 +/- 21 ml/m(2). The number of re-entrant regions was 4.3 +/- 1.7 per patient. LA LGE imaging was significantly associated with the number of re-entrant regions (R = 0.52; p = 0.001), LA volume (R = 0.62; p < 0.0001), and AF duration (R = 0.54; p = 0.0007). Regional analysis demonstrated a clustering of re-entrant activity at LGE borders. Areas with high re-entrant activity showed higher local LGE density as compared with the remaining atrial areas (p < 0.0001). Failure to achieve AF termination during ablation was associated with higher LA LGE burden (p < 0.001), higher number of re-entrant regions (p < 0.001), and longer AF duration (p = 0.008).CONCLUSIONS The number of re-entrant regions during AF relates to the extent of LGE on CMR, with the location of these regions clustering to LGE areas. These characteristics affect procedural outcomes of ablation. (C) 2018 by the American College of Cardiology Foundation.