Left Atrial Flow Stasis in Patients Undergoing Pulmonary Vein Isolation for Paroxysmal Atrial Fibrillation Using 4D-Flow Magnetic Resonance Imaging

Featured Application Left atrial stasis is a useful metric to evaluate hemodynamic recovery of the left atrial after pulmonary vein ablation. Atrial fibrillation (AF) is associated with systemic thrombo-embolism and stroke events, which do not appear significantly reduced following successful pulmonary vein (PV) ablation. Prior studies supported that thrombus formation is associated with left atrial (LA) flow alterations, particularly flow stasis. Recently, time-resolved three-dimensional phase-contrast (4D-flow) showed the ability to quantify LA stasis. This study aims to demonstrate that LA stasis, derived from 4D-flow, is a useful biomarker of LA recovery in patients with AF. Our hypothesis is that LA recovery will be associated with a reduction in LA stasis. We recruited 148 subjects with paroxysmal AF (40 following 3-4 months PV ablation and 108 pre-PV ablation) and 24 controls (CTL). All subjects underwent a cardiac magnetic resonance imaging (MRI) exam, inclusive of 4D-flow. LA was isolated within the 4D-flow dataset to constrain stasis maps. Control mean LA stasis was lower than in the pre-ablation cohort (30 +/- 12% vs. 47 +/- 18%, p < 0.001). In addition, mean LA stasis was reduced in the post-ablation cohort compared with pre-ablation (36 +/- 15% vs. 47 +/- 18%, p = 0.002). This study demonstrated that 4D flow-derived LA stasis mapping is clinically relevant and revealed stasis changes in the LA body pre- and post-pulmonary vein ablation.

Automated summary

This study demonstrates the clinical relevance of 4D flow-derived LA stasis mapping in evaluating left atrial recovery in patients with atrial fibrillation. It reveals a reduction in left atrial stasis following successful pulmonary vein ablation, with control subjects showing significantly lower stasis compared to pre-ablation patients. The findings highlight the importance of assessing left atrial stasis maps for evaluating the impact of pulmonary vein ablation on left atrial function.