Arrhythmias

1354264 - Post-ablation 4D flow restoration in atrial fibrillation patients with high CHA2DS2-VASc score quantified by novel 4D Hemodynamic Signature Index (HSI): A follow-up study

Friday, January 27, 2023

12:20 PM – 1:20 PM

Location: Pacific Jewel

Presenting Author(s)

TN

Thara Nallamothu, BA

Graduate Student
Northwestern University, United States

Primary Author(s)

TN

Thara Nallamothu, BA

Graduate Student
Northwestern University, United States

Co-Author(s)

Daniel C. Lee, MD

Associate Professor of Medicine (Cardiology) and Radiology
Northwestern University
Chicago, Illinois, United States
PG

Philip Greenland, MD

Professor of Preventive Medicine (Epidemiology) and Medicine (Cardiology)
Northwestern University
Chicago, Illinois, United States
RP

Rod Passman, MD

Professor of Medicine (Cardiology) and Preventive Medicine
Northwestern University
Chicago, Illinois, United States
Mohammed Elbaz, PhD

Assistant Professor
Northwestern University
Chicago, Illinois, United States

Disclosure(s):

Daniel C. Lee, MD: No relevant disclosure to display

Background: Atrial fibrillation (AF) patients have a 5-fold increased risk of stroke. Left atrial (LA) ablation is effective in reducing AF burden. However, current stroke risk scores (CHA₂DS₂-VASc) used to select patients for treatment do not account for LA flow abnormalities pre- or post-ablation. 4D Flow CMR can provide additional information, but current quantification methods cannot fully capture the complex LA flow alterations that may include jets, vortices, and stagnations simultaneously. A novel Hemodynamic Signature Index (HSI) was recently proposed that quantifies the entire 4D Flow LA flow dynamics by deriving the patient’s unique 4D flow CMR profile from millions of vector associations^1-3. Here, we aimed to employ the novel HSI index to quantify post-ablation 4D LA flow changes and association with stroke risk.

Methods: In this follow-up study, N=33 AF patients (7 female, 60±13 years) had 4D flow CMR pre-ablation and 6 months post-ablation. 7 patients had AF recurrence within 12 months post-ablation. N=30 healthy volunteers were included as controls (13 female, 65±3 years, age p=0.15). Per published methods^1,2, Fig. 1 summarizes the HSI computation from profiles of 2±1 million 4D LA flow vector-pair disparities. We computed the HSI pre-ablation (HSI_pre) and post-ablation (HSI_post). We evaluated the HSI changes in two stroke risk score groups: N=11 low risk (CHA₂DS₂-VASc=0 in males, CHA₂DS₂-VASc≤1 in females) and N=22 high risk (CHA₂DS₂-VASc≥1 in males, CHA₂DS₂-VASc≥2 in females).

Results: HSI_pre was significantly elevated vs. controls (p=0.03), while HSI_post was not (p=0.5). HSI_post showed a significant reduction vs. HSI_pre (p=0.02), indicating that post-ablation 4D LA flow was more restored versus controls (Fig.2). 23 patients showed 4D flow restoration (HSI_post< HSI_pre, Fig. 2a), but 10 patients showed deterioration (HSI_post>HSI_pre, Fig. 2b). Of the deteriorations, the two highest HSI_post values were in patients with AF recurrence (Fig. 2b). HSI_post vs. HSI_pre was significantly reduced in the high stroke risk group (p=0.04, Fig 2c) but not significantly different in the low risk group (p=0.41). The high risk group showed elevated HSI_pre vs. controls (p=0.04), but their HSI_post was no longer different vs. controls (p=0.7), indicating restoration to control-like flow. Fig. 3 shows a patient with flow restoration and another with deterioration.

Conclusion: The novel Hemodynamic Signature Index (HSI) quantified 4D flow alterations post AF ablation. Previous work has shown that the HSI is sensitive to 4D (3D+time) LA flow changes in AF³ and highly robust to data uncertainties¹. Results here indicate that ablation modulates 3D LA blood flow dynamics in AF patients. Post-ablation flow restoration relative to controls in the high stroke risk score patients indicates that stroke risk may need re-evaluation following ablation. Hence, warranting further study into incorporating LA flow changes in stroke risk. Larger studies are needed to assess the potential prognostic value of the HSI.