Left atrial vortex size and velocity distributions by 4D flow MRI in patients with paroxysmal atrial fibrillation: Associations with age and CHA
            2
            DS
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            ‐VASc risk score

Introduction: Clinical scores used for stroke risk estimation in atrial fibrillation (AF) have limited predictive accuracy. 4D Flow MRI can acquire blood flow in a volume data set encompassing the entire left atrium (LA) with quantification of blood velocity in 3 orthogonal directions for every voxel at multiple time points throughout the cardiac cycle (4D = 3D coverage + time). Hypothesis: 4D Flow MRI can assess 3D LA flow abnormalities in AF patients, which may potentially be linked to stroke. Methods: We performed 4D flow MRI in 30 volunteers (10 young, 20 older) and 70 patients with a history of AF: 40 in sinus rhythm (AF-sinus) and 30 in AF during MRI scan (AF-afib). The typical LA contained 3000 voxels and 18 phases per voxel. LA flow velocity histograms for each patient were quantified by mean LA velocity, median LA velocity, and the percentage of LA velocities < 0.2 m/s (%stasis). CHA2DS2-VASc scores were calculated for each patient. Results: Mean LA velocity, median LA velocity, and %stasis were significantly different between groups: young volunteers (0.26±0.02 m/s, 0.23±0.02 m/s, 37.3±7.6%), older volunteers (0.21±0.03 m/s, 0.20±0.03 m/s, 52.2±16.0%), AF-sinus (0.18±0.03 m/s, 0.17±0.03 m/s, 67.5±16.9%), and AF-afib (0.16±0.01 m/s, 0.14±0.03 m/s, 78.2±12.9%), p < 0.0125 for all comparisons. CHA2DS2-VASc had moderate but significant correlations with mean LA velocity (R 2 =0.27, p<0.001), median LA velocity (R 2 =0.23, p<0.001), and stasis% (R 2 =0.26, p<0.001). LA flow indices also correlated significantly with age, LA volume, and left ventricular ejection fraction (LVEF) as seen in the Table. Conclusions: Left atrial 4D flow MRI is a novel approach to identify patients with reduced LA blood velocities and increased LA stasis. Further study is needed to determine whether these measures can improve upon the CHA2DS2-VASc score for stroke risk prediction and enhance individual decisions on anticoagulation in patients with AF.

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Altered left atrial 4D flow characteristics in patients with paroxysmal atrial fibrillation in the absence of apparent remodeling

Scientific Reports ◽

10.1038/s41598-021-85176-8 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Ahmet Demirkiran ◽

Raquel P. Amier ◽

Mark B. M. Hofman ◽

Rob J. van der Geest ◽

Lourens F. H. J. Robbers ◽

...

Keyword(s):

Atrial Fibrillation ◽

Sinus Rhythm ◽

Flow Velocity ◽

Paroxysmal Atrial Fibrillation ◽

Left Atrial ◽

Peak Flow ◽

Thrombus Formation ◽

Clinical Value ◽

4D Flow ◽

Ssfp Cine

AbstractThe pathophysiology behind thrombus formation in paroxysmal atrial fibrillation (AF) patients is very complex. This can be due to left atrial (LA) flow changes, remodeling, or both. We investigated differences for cardiovascular magnetic resonance (CMR)-derived LA 4D flow and remodeling characteristics between paroxysmal AF patients and patients without cardiac disease. In this proof-of-concept study, the 4D flow data were acquired in 10 patients with paroxysmal AF (age = 61 ± 8 years) and 5 age/gender matched controls (age = 56 ± 1 years) during sinus rhythm. The following LA and LA appendage flow parameters were obtained: flow velocity (mean, peak), stasis defined as the relative volume with velocities < 10 cm/s, and kinetic energy (KE). Furthermore, LA global strain values were derived from b-SSFP cine images using dedicated CMR feature-tracking software. Even in sinus rhythm, LA mean and peak flow velocities over the entire cardiac cycle were significantly lower in paroxysmal AF patients compared to controls [(13.1 ± 2.4 cm/s vs. 16.7 ± 2.1 cm/s, p = 0.01) and (19.3 ± 4.7 cm/s vs. 26.8 ± 5.5 cm/s, p = 0.02), respectively]. Moreover, paroxysmal AF patients expressed more stasis of blood than controls both in the LA (43.2 ± 10.8% vs. 27.8 ± 7.9%, p = 0.01) and in the LA appendage (73.3 ± 5.7% vs. 52.8 ± 16.2%, p = 0.04). With respect to energetics, paroxysmal AF patients demonstrated lower mean and peak KE values (indexed to maximum LA volume) than controls. No significant differences were observed for LA volume, function, and strain parameters between the groups. Global LA flow dynamics in paroxysmal AF patients appear to be impaired including mean/peak flow velocity, stasis fraction, and KE, partly independent of LA remodeling. This pathophysiological flow pattern may be of clinical value to explain the increased incidence of thromboembolic events in paroxysmal AF patients, in the absence of actual AF or LA remodeling.

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LA velocities and stasis assessed by 4D flow MRI are closely associated with LAA peak velocities by Doppler TEE in patients with atrial fibrillation

Journal of Cardiovascular Magnetic Resonance ◽

10.1186/1532-429x-18-s1-p1 ◽

2016 ◽

Vol 18 (S1) ◽

Author(s):

Michael Mark ◽

Nicholas Furiasse ◽

Daniel C Lee ◽

Jason Ng ◽

James C Carr ◽

...

Keyword(s):

Atrial Fibrillation ◽

4D Flow Mri ◽

4D Flow ◽

Flow Mri

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Assessment of left and right atrial 3D hemodynamics in patients with atrial fibrillation: a 4D flow MRI study

The International Journal of Cardiovascular Imaging ◽

10.1007/s10554-015-0830-8 ◽

2016 ◽

Vol 32 (5) ◽

pp. 807-815 ◽

Cited By ~ 18

Author(s):

Michael Markl ◽

Maria Carr ◽

Jason Ng ◽

Daniel C. Lee ◽

Kelly Jarvis ◽

...

Keyword(s):

Atrial Fibrillation ◽

Right Atrial ◽

4D Flow Mri ◽

4D Flow ◽

Flow Mri ◽

Left And Right ◽

Mri Study

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Left atrial blood stasis by 4D flow MRI correlates with stroke risk estimation by CHA2DS2-VASc score

Journal of Cardiovascular Magnetic Resonance ◽

10.1186/1532-429x-16-s1-o51 ◽

2014 ◽

Vol 16 (S1) ◽

Cited By ~ 2

Author(s):

Daniel C Lee ◽

Michael Markl ◽

Jacob Fluckiger ◽

Jason Ng ◽

James C Carr ◽

...

Keyword(s):

Left Atrial ◽

Stroke Risk ◽

Risk Estimation ◽

Blood Stasis ◽

4D Flow Mri ◽

4D Flow ◽

Flow Mri

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P585Intra left ventricular hemodynamics assessed using 4D flow MRI in the patient with left ventricular thrombus

European Heart Journal ◽

10.1093/eurheartj/ehz747.0194 ◽

2019 ◽

Vol 40 (Supplement_1) ◽

Author(s):

T Sakakibara ◽

K Suwa ◽

Y Kaneko ◽

K Akita ◽

R Sato ◽

...

Keyword(s):

Diagnostic Accuracy ◽

Flow Velocity ◽

Left Ventricular ◽

Area Ratio ◽

Lv Function ◽

4D Flow Mri ◽

4D Flow ◽

Lower Flow ◽

Vortex Size ◽

Flow Mri

Abstract Background Early detection of left ventricular mural thrombus (LVT) in patients with reduced ejection fraction (EF) is crucial in prevention of arterial embolism. 3D-cine phase-contrast magnetic resonance imaging (4D flow MRI) can visualize the intra-LV vortex flow in diastole and quantify the maximum flow velocity (Vmax) at the apex. it remains, however, unknown whether 4D flow MRI is useful for detecting LVT. Purpose The purpose of our study is to examine the intra-LV vortex formation and flow velocity in patients with severe LV dysfunction using 4D Flow MRI, and to compare differences in intra-LV flow dynamics between patients with and without LVT. We also examined the diagnostic accuracy to detect LVT by 4D flow MRI. Methods Twenty-nine patients with impaired LV function (LVEF 25.8±7.4%, 62.5±12.3 years old, 24 males, 11 with ischemic cardiomyopathy, 9 with LVT) underwent 4D flow MRI from January 2012 to August 2018 in our institution. Intra-LV vortex size was evaluated as vortex/LV area ratio by streamline imaging (Figure 1). The diagnostic accuracy to predict LVT by vortex size and Vmax at the apex was determined by ROC analysis. Results The vortex was smaller (vortex/LV area ratio; 30.6±7.0% vs. 45.1±9.0%, p<0.05) and Vmax at the apex was lower (0.20±0.04 m/s vs. 0.28±0.09 m/s, p=0.013) in patients with LVT compared to those without LVT. The AUC was 0.789 for Vmax (cut-off value=0.226 m/s, sensitivity=0.889, specificity=0.650) and was 0.900 for vortex/LV area ratio (cut-off value=34.7%, sensitivity=0.889, specificity=0.850). Figure 1 Conclusion The smaller size of intra-LV vortex and the lower flow velocity at the LV apex may have association with LVT formation in patients with reduced EF. 4D flow MRI might be useful to predict LVT formation. Large scale longitudinal study is warranted to evaluate the incidence of LVT in the patients with lower flow velocity. Acknowledgement/Funding None

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