Background/Introduction: The role of pulmonary veins (PVs) in triggering Atrial Fibrillation (AF) is well established. The diameter and morphological features of the PVs in relationship to AF have been studied in animal and human models. The PV sleeve length has not been characterised in vivo in patients undergoing AF ablation. We hypothesised that left atrial (LA) dilatation is associated with shorter PV sleeve length due to atrialisation of the PV myocardium. We aimed to find whether there is a relationship between LA size and PV sleeve length in patients undergoing Radiofrequency (RF) ablation.
Methods: We measured the PV sleeve length in 25 consecutive patients undergoing RF ablation in our department. LA geometry and voltage maps were created using the CARTO 3D electro-anatomical mapping system with distal CS pacing. Persistent AF patients were cardioverted to SR. The bipolar mapping catheter was placed in each PV and the most distal electrical signal was marked on the map. The PV length from the ostium to the marked spot was measured both at the surface of the atrium and endoscopically using a clipping plane view with mean measurements calculated per PV. The left atrial size was measured on transthoracic echocardiography calculating the LA diameter in the long parasternal axis and the LA volume in the 4-chamber window.
Results: Out of the 25 patients (mean age 65 years, 44% female), 11 underwent ablation for persistent and 16 for paroxysmal AF. Mean LA diameter was calculated at 4.1 ± 0.8 cm and mean LA volume at 62.5 ± 21.3 ml. LA volume and diameter were statistically significantly higher in patients with persistent AF (75.9 ml vs 51.5 ml and 4.6 cm vs 3.7 cm respectively). The average sleeve size of each patient’s PVs was not statistically different between patients with persistent and paroxysmal AF (14.38 mm vs 16.03 mm respectively, p=0.14). Examining each PV individually, only the right upper PV sleeve was statistically longer in patients with paroxysmal AF (18.8 mm vs 14.9 mm in persistent AF, p=0.014). A simple linear regression was calculated to predict PV sleeve length base on LA size. A significant equation was found (F(1,22)=14.97, p=0.001) with and R2 of 0.405 for the LA volume and (F(1,21)=11.08, p=0.003) with and R2 of 0.345 for the LA diameter. PV sleeve length decreased by 0.8 mm for every 10 ml of LA volume increase and similarly by 2 mm for every cm of LA diameter increase.
Conclusion(s): We observed an inverse relationship between PV sleeve length and LA size both by volume and diameter. Although there was no statistical difference there was a trend towards shorter length PV sleeves in patients with persistent AF. Our findings suggest a possible process leading to PV sleeve atrialisation in patients with dilated LA that could influence the ablation strategy in this cohort.
Figure 1 – Relationship between PV sleeve size and LA size in volume and diameter in AF ablation patients.