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Atrial fibrillation (AF) is a global common disease which 33.5 million individuals suffer from. Conventional cardiac magnetic resonance and 4D flow magnetic resonance imaging have been used to study AF patients. We propose a left ventricular flow component analysis from 4D flow for AF detection. This method was applied to healthy controls and AF patients before catheter ablation. Retained inflow, delayed ejection, and residual volume had a significant difference between controls and the AF group as well as a conventional LV stroke volume parameter, and among them, residual volume was the strongest parameter to detect AF.

Background: Characterization of left atrial (LA) hemodynamics in paroxysmal atrial fibrillation (PAF) may provide valuable insights for thromboembolic risk., Purpose: To evaluate LA vortex formation and velocity distributions by 4D flow MRI and identify associations with age, LA/LV (left ventricle) function, and established risk scores., Study Type: Prospective clinical., Population: Patients with PAF (n = 45, 46 ± 14 years) and healthy controls (n = 15, 54 ± 9 years) were enrolled., Mri Sequences: 3T standardized cardiac MRI protocol inclusive of 4D flow MRI., Assessment: Flow analysis planes were prescribed at each pulmonary vein. Velocity distribution analysis and vortex size quantification by the Lambda2 (λ 2 ) method were performed in the LA., Statistics: Pearson or Spearman's correlation coefficients, r, were calculated to identify relationships between 4D flow-derived LA parameters and age, LA/LV function, and CHA 2 DS 2 -VASc stroke risk score. Univariate and multivariate determinants of stroke risk were assessed using linear regressions. To compare parameters within multiple groups, one-way analysis of variance or Kruskal-Wallis was used., Results: LA vortice sizes were observed in all subjects using λ 2 showing inverse correlations with peak pulmonary vein inflow velocities (P < 0.05), and positive correlations with LA volume (P < 0.05). Vortex size was elevated in PAF at all phases of the cardiac cycle, being most prominent at end early diastole (3.98 ± 1.84 cm 3 vs. 6.93 ± 3.11 cm 3 , P = 0.001). Velocity distribution analysis showed a greater incidence of flow stasis among patients with PAF (P < 0.05). In univariate regression, vortex size was associated with the CHA 2 DS 2 -VASc risk score at peak systole (0.457 ± 0.038, P ≤ 0.001). However, in multivariate regression age was the dominant determinant of stroke risk (0.348 ± 0.012, P = 0.006)., Data Conclusion: This study demonstrated that LA vortex size is increased among low-risk patients with PAF and is associated with the CHA 2 DS 2 -VASc risk score. Age remained the dominant determinant of stroke risk., Level of Evidence: 2 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2020;51:871-884., (© 2019 International Society for Magnetic Resonance in Medicine.)

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. [ABSTRACT FROM AUTHOR]

Background: Characterization of left atrial (LA) hemodynamics in paroxysmal atrial fibrillation (PAF) may provide valuable insights for thromboembolic risk.Purpose: To evaluate LA vortex formation and velocity distributions by 4D flow MRI and identify associations with age, LA/LV (left ventricle) function, and established risk scores.Study Type: Prospective clinical.Population: Patients with PAF (n = 45, 46 ± 14 years) and healthy controls (n = 15, 54 ± 9 years) were enrolled.Mri Sequences: 3T standardized cardiac MRI protocol inclusive of 4D flow MRI.Assessment: Flow analysis planes were prescribed at each pulmonary vein. Velocity distribution analysis and vortex size quantification by the Lambda2 (λ2 ) method were performed in the LA.Statistics: Pearson or Spearman's correlation coefficients, r, were calculated to identify relationships between 4D flow-derived LA parameters and age, LA/LV function, and CHA2 DS2 -VASc stroke risk score. Univariate and multivariate determinants of stroke risk were assessed using linear regressions. To compare parameters within multiple groups, one-way analysis of variance or Kruskal-Wallis was used.Results: LA vortice sizes were observed in all subjects using λ2 showing inverse correlations with peak pulmonary vein inflow velocities (P < 0.05), and positive correlations with LA volume (P < 0.05). Vortex size was elevated in PAF at all phases of the cardiac cycle, being most prominent at end early diastole (3.98 ± 1.84 cm3 vs. 6.93 ± 3.11 cm3 , P = 0.001). Velocity distribution analysis showed a greater incidence of flow stasis among patients with PAF (P < 0.05). In univariate regression, vortex size was associated with the CHA2 DS2 -VASc risk score at peak systole (0.457 ± 0.038, P ≤ 0.001). However, in multivariate regression age was the dominant determinant of stroke risk (0.348 ± 0.012, P = 0.006).Data Conclusion: This study demonstrated that LA vortex size is increased among low-risk patients with PAF and is associated with the CHA2 DS2 -VASc risk score. Age remained the dominant determinant of stroke risk.Level Of Evidence: 2 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2020;51:871-884. [ABSTRACT FROM AUTHOR]