Relationship Between Fibrosis Detected on Late Gadolinium-Enhanced Cardiac Magnetic Resonance and Re-Entrant Activity Assessed With Electrocardiographic Imaging in Human Persistent Atrial Fibrillation

Abstract

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/m2. 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.

The Fibrotic Substrate in Persistent Atrial Fibrillation Patients: Comparison Between Predictions From Computational Modeling and Measurements From Focal Impulse and Rotor Mapping

“…Our work using such models has identified specific spatial patterns of fibrotic tissue that promote AF perpetuation (Zahid et al, 2016a) and these findings are corroborated by clinical evidence (Cochet et al, 2018). Also, in a study complementary to the present work, we compared rotor harboring regions, as characterized by pre-ablation non-invasive electrocardiographic imaging (ECGI), with those predicted in patient-specific models reconstructed from LGE-MRI scans of the same patients (Boyle et al, 2018).…”

Do most patients with obesity or type 2 diabetes, and atrial fibrillation, also have undiagnosed heart failure? A critical conceptual framework for understanding mechanisms and improving diagnosis and treatment

“…Coronary microvascular dysfunction is exceptionally common in HFpEF and, when present, is associated with a two‐fold increase in the prevalence of AF . Cardiac magnetic resonance imaging (MRI) reveals meaningful myocardial fibrosis (in the LA and LV) in both patients with HFpEF and those with AF . Fibrosis is indicative of an underlying atrial and ventricular myopathy and may precede the clinical identification of AF or HFpEF …”

“…HFpEF), the finding of ventricular fibrosis doubles the procedural failure rate . Therapeutic futility may be particularly common in patients with longstanding AF (with or without overt HFpEF) . In a cohort with preserved ejection fraction and permanent AF, patients with LV fibrosis had an exceptionally high rate of AF recurrence following catheter ablation; the 1‐year procedural success rate in those with extensive fibrosis and LV hypertrophy was only 7% .…”

“…29,30 Cardiac magnetic resonance imaging (MRI) reveals meaningful myocardial fibrosis (in the LA and LV) in both patients with HFpEF 31-36 and those with AF. 37,38 Fibrosis is indicative of an underlying atrial and ventricular myopathy and may precede the clinical identification of AF or HFpEF. 32,39,40…”

“…235 Therapeutic futility may be particularly common in patients with longstanding AF (with or without overt HFpEF). 37,241,242 In a cohort with preserved ejection fraction and permanent AF, patients with LV fibrosis had an exceptionally high rate of AF recurrence following catheter ablation; the 1-year procedural success rate in those with extensive fibrosis and LV hypertrophy was only 7%. 243 Even in patients with paroxysmal AF, the diagnosis of HFpEF or biomarkers of systemic inflammation presages a high rate of AF recurrence.…”