Late Enhancement Computed Tomography for Left Atrial Fibrosis Imaging: A Pilot “Proof-of-Concept” Study

Figures

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  Figure 1. Focal late enhancement (LE). Images (A) of the early phase CTA were co-axially aligned with late enhancement CT performed 7 min after contrast agent injection (B) (2-step CT protocol). (A) LAWT was measured at 3 sites along the LA ridge, and the mean was calculated. The left anterior descending (LAD) coronary artery served as a landmark for co-axial alignment in this patient: a 52-year-old-female with persistent AF, a CVRF of active smoking. The LAWT was >2 mm (A) and focal LE with 130 HU (B) was observed. (C,D) Results in a 54-year-old male with AF prior to planning LA ablation. The mean LAWT was 4 mm (C), and a focal dense spot of late enhancement (LE) was identified at the exact site of maximal LAWT, with 102 HU (D).

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  Figure 2. Late enhancement (LE) patterns of left atrial fibrosis by CT. The majority had focal (77.1%) LE, while diffuse (16.5%) and mixed LE patterns (n = 5, 6.3%) were less frequently observed.

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  Figure 3. Correlation of anterior left atrial wall thickness (LAWT) with late enhancement (LE) CT density (HU). A weak correlation was found (r = 0.229; p = 0.041). HU, Hounsfield units; mm, millimeters.

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  Figure 4. Late enhancement (LE) density (HU) in focal (1) compared with diffuse (2) fibrosis patterns. No difference was observed in CT density (Hounsfield Units, HU) (p = 0.360).

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  Figure 5. A 59-year-old-male with paroxysmal AF, a BMI of 21.5, the CVRF of dyslipidemia, and left atrial wall thickness (LAWT) of 3.3 mm, with a low-voltage area on EAM (anterior LA wall, green/yellow area) (upper panel, (A)) matching with focal LE (128 HU) on late enhancement (LE) CT (lower panel, (B)).

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  Figure 6. A 59-year-old male with a BMI of 27.8 kg/m2, and a LVEF of 68% with paroxysmal AFIB and severe left atrial wall thickening (LAWT) with a maximum of 5.1 mm during early-phase CT (Panel (A), arrows) and linear late enhancement during late-phase CT (Panel (B), arrows), indicating diffuse fibrosis, which was correlated with low-voltage areas along the entire anterior left atrial wall during electroanatomical mapping (EAM). (Panel (C)) All 20 spots were positive for low-voltage areas of <0.5 mV, shown as red areas (yellow arrows), with values ranging from 0.015 to 0.12 (mean: 0.024 mV). While LA ablation with pulmonary vein isolation was successful, the patient experienced recurrent AFIB after 3 months, and a second LA ablation was performed 7 months later.