Atrial Structure and Function 5 Years After Successful Ablation for Persistent Atrial Fibrillation: An MRI Study

Atrial Function After Persistent AF Ablation. Introduction: The atrial outcome after extensive ablation is unknown. We sought to quantify atrial structure and function years after successful ablation for persistent atrial fibrillation (PsAF). Methods and Results: We studied after 80 +/- 15 months 26 patients (54 +/- 8 years, 1 woman) with PsAF successfully treated by ablation (2.2 +/- 0.7 stepwise approach procedures, cumulative RF duration 126 +/- 37 minutes). At follow-up atrial scar burden and atrial outflows were quantified using delayed-enhanced and velocity-encoded MRI, respectively. Cine imaging was used to quantify atrial conduit function (CF), active emptying fraction (AEF), expansion index (EI), and the inter-appendage mechanical activation delay. Patients underwent exercise testing at baseline and follow-up. LA and RA scar extent were 29 +/- 6 and 4.3 +/- 2.8%, respectively. LA and RA AEF were 10.0 +/- 5.3 and 30 +/- 8%. Mean inter-appendage delay was 83 +/- 47 ms [42-217]. Complete LAA isolation was found in 3 patients. A wave was absent in 9/26 patients. LA scar extent related to the number of procedures (R = 0.58, P = 0.002) and total RF duration (R = 0.56, P = 0.003). Among follow-up characteristics, LA scar extent related to LAAEF (R = -0.73, P < 0.0001), LAEI (R = -0.64, P = 0.0003), A-wave peak (R = -0.72, P < 0.0001), and inter-appendage mechanical delay (R = 0.47, P = 0.02). At multivariable analysis, LA scar extent was independently related to LAAEF and LAEI. LAAEF and LA scar extent correlated with exercise capacity at follow-up (R = 0.44, P = 0.02, and R = -0.40; P = 0.04). Conclusion: LA contractility and compliance are markedly impaired years after successful PsAF ablation. LA dysfunction is closely related to scar burden.