Assessment of Beat-To-Beat Variability in Left Atrial Hemodynamics Using Real Time Phase Contrast MRI in Patients With Atrial Fibrillation

Amanda L. DiCarlo, Hassan Haji-Valizadeh, Rod Passman, Philip Greenland, Patrick McCarthy, Daniel C. Lee, Daniel Kim, Michael Markl*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Background: Hemodynamic assessment of left atrial (LA) flow using phase contrast MRI provides insight into thromboembolic risk in atrial fibrillation (AF). However, conventional flow imaging techniques are averaged over many heartbeats. Purpose: To evaluate beat-to-beat variability and LA hemodynamics in patients with AF using real time phase contrast (RTPC) MRI. Study Type: Prospective. Subjects: Thirty-five patients with history of AF (68 ± 10 years, nine female), 10 healthy controls (57 ± 19 years, four female). Field Strength/Sequence: 5T, 2D RTPC with through-plane velocity-encoded gradient echo sequence and 4D flow MRI with three-directional velocity-encoded gradient echo sequence. Assessment: RTPC was continuously acquired for a mid-LA slice in all subjects. 4D flow data were interpolated at the RTPC location and normally projected for comparison with RTPC. RR intervals extracted from RTPC were used to calculate heart rate variability (HRV = interquartile range over median × 100%). Patients were classified into low (<9.7%) and high (>9.7%) HRV groups. LA peak/mean velocity and stasis (%velocities < 5.8 cm/sec) were calculated from segmented 2D images. Variability in RTPC flow metrics was quantified by coefficient of variation (CV) over all cycles. Statistical Tests: Pearson's correlation coefficient (r), Bland–Altman analysis, Kruskal–Wallis test. A P value < 0.05 was considered statistically significant. Results: RTPC and 4D flow measurements were strongly/significantly correlated for all hemodynamic parameters (R2 = 0.75–0.83) in controls. Twenty-four patients had low HRV (mean = 4 ± 2%) and 11 patients had high HRV (27 ± 9%). In patients, increased HRV was significantly correlated with CV of peak velocity (r = 0.67), mean velocity (r = 0.51), and stasis (r = 0.41). A stepwise decrease in peak/mean velocity and increase in stasis was observed when comparing controls vs. low HRV vs. high HRV groups. Mean velocity and stasis differences were significant for control vs. high HRV groups. Conclusions: RTPC may be suitable for assessing the impact of HRV on hemodynamics and provide insight for AF management in highly arrhythmic patients. Evidence Level: 1. Technical Efficacy: Stage 2.

Original languageEnglish (US)
Pages (from-to)763-771
Number of pages9
JournalJournal of Magnetic Resonance Imaging
Issue number3
StatePublished - Sep 2023


  • 4D flow MRI
  • atrial fibrillation
  • heart rate variability
  • real time phase contrast

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging


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