SCMR 22nd Annual Scientific Sessions
Background: Left atrial (LA) enlargement is a marker for increased risk of atrial fibrillation (AF). However, LA remodeling is a complex process that is poorly understood, and LA geometric remodeling may also be associated with the development of AF [1-3]. We sought to determine whether LA spherical remodeling predicts late AF recurrence after pulmonary vein isolation (PVI).
Methods: Two hundred twenty-seven consecutive patients scheduled for their first PVI for paroxysmal or persistent AF who underwent cardiovascular magnetic resonance (CMR) before and within 6 months after PVI were retrospectively identified. LA sphericity index was computed as the ratio of the measured LA maximum volume to the volume of a sphere with maximum LA length diameter.
Results: During mean follow-up of 25 months, 88 patients (39%) experienced late recurrence of AF. Multivariable Cox regression analyses identified increased pre-PVI LA sphericity index as an independent predictor of late AF recurrence (hazard ratio [HR], 1.32; 95% confidence interval [CI], 1.07-1.62, p=0.009). Patients in the highest LA sphericity index tertile were at highest risk of late recurrence (highest vs. lowest: 59% vs. 28%, P<0.001). The integration of the LA sphericity index to the LA minimum volume index and passive emptying fraction provided important incremental prognostic information for predicting late AF recurrence post PVI (continuous net reclassification improvement, 0.47; 95%CI, 0.14-0.79, p=0.005). The intraclass correlation coefficients for inter-observer and intra-observer measurements of LA sphericity index were 0.93 (95% CI 0.75 to 0.98) and 0.96 (95% CI 0.85 to 0.99), respectively.
Conclusion: The assessment of pre-PVI LA geometric remodeling provides incremental prognostic information regarding late AF recurrence and may be useful to identify those for whom PVI has reduced success or for whom more aggressive ablation or medications may be useful. Cine CMR-derived LA sphericity index can be derived without the cost of additional scan time or the need for gadolinium contrast.