Cardiac tomography predictors of functional left atrium substrate in candidates to atrial fibrillation ablation
L Pistelli, M Parollo, A N D R E A Di Cori, R De Lucia, A Canu, M Giannotti Santoro, V Barletta, L Segreti, S Sbragi, G Grifoni, S Viani, G ZucchelliAbstract
Background
In recent years, interest has grown in the functional substrate underlying atrial fibrillation (AF), particularly slow conduction velocity (SC) [1-3].
Purpose
To investigate the relationship between low-attenuation epicardial adipose tissue (I-EAT), aortic root and esophagus proximity to the left atrium (LA), and conduction velocities and voltage on high-density electroanatomic maps.
Methods
We retrospectively enrolled 22 consecutive patients undergoing AF ablation who had both cardiac CT and high-density LA mapping in sinus rhythm. Images were processed with dedicated software to identify I-EAT and aortic root and esophagus proximity to the LA endocardium (<1 mm). Predefined HU thresholds from prior literature were applied. [4] The LA was divided into segments, defined automatically according to a previously described method to ensure comparability: roof, posterior wall, septum, anterior wall and lateral wall. [3] Non suitable segments were excluded and a segment-level analysis was performed. Sinus-rhythm activation maps were acquired using a window from P-wave onset to QRS onset, with 12-ms isochrones. Slow conduction was defined as ≥3 isochrones within a 1-cm radius (propagation velocity <27 cm/s). Low voltage (LVA) was defined as bipolar potential <0.5 mV. [2, 5].
Results
258 segments from 22 patients were analyzed. 176 segments (68%) showed SC. Most SC zone were found in anterior wall (65/176; 36.9%). On univariate analysis, SC was associated with persistent AF (p=0.021), low-attenuation epicardial adipose tissue (I-EAT; p<0.001), and aortic-root proximity <1 mm (p=0.034), but not esophageal proximity <1 mm (p=0.718). In multivariable logistic regression, I-EAT (OR 3.69, 95% CI 1.9–7.0; p<0.001), aortic-root proximity (OR 3.3, 95% CI 1.3–8.4; p=0.01), and persistent AF (OR 2.1, 95% CI 1.1–3.9; p=0.02) remained independently associated with SC. [Figure 1] Eighty-three segments (32%) demonstrated low-voltage areas (LVA); 82/83 (99%) colocalized within SC zones (p<0.001). At univariate analysis, LVA was associated with I-EAT (p=0.020), aortic-root proximity (p=0.019), persistent AF (p<0.001), and female sex (p=0.03). In multivariable analysis, LVA was independently associated with SC (OR 59.3, 95% CI 7.9–447.4; p<0.001), persistent AF (OR 4.31, 95% CI 2.2–8.6; p<0.001), and female sex (OR 2.3, 95% CI 1.1–4.7; p=0.03), but not I-EAT (OR 1.62, 95% CI 0.8–3.4; p=0.20) and aortic-root proximity (OR 1.6, 95% CI 0.7–3.9; p=0.38). [Figure 1]
Conclusions
Aortic root proximity and low-attenuation epicardial fat are independently associated with SC in the LA. Slow conduction, female sex, and persistent AF are independently associated with LVA.Figure 1Figure 2