Background: Radiofrequency (RF) ablation procedures to electrically isolate the pulmonary veins (PV) from the left atrium are frequently used to treat atrial fibrillation.  We hypothesized that changes in PV size after RF ablation would correlate with the volume of ostial PV scar as assessed by high resolution late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR). 

Methods: The study cohort included 23 subjects.  Contrast enhanced CMR of the PV was obtained before and 42 ± 18 days after RF ablation.  High-resolution LGE CMR of the left atrium and PV was obtained using a 3D, ECG triggered, navigator gated technique.  

Results: A total of 85 PV were analyzed.  Imaging after RF ablation demonstrated a reduction in PV diameter from 22 ± 7 mm to 21 ± 6 mm after (p = 0.001) with a reduction in cross-sectional area (CSA) from 285 ± 141 to 246 ± 110 (p < 0.001).  There was a significant correlation of PV ostial normalized scar volume with the change in PV diameter (r =-0.21, p =0.049) and CSA (r =-0.28, p =0.010) after AF ablation.  PV in the highest quartile for PV scar had the greatest reduction in diameter and CSA (p <0.05 for both). 

Conclusion: PV size decreases significantly after RF ablation for the treatment of AF.  The change in PV size is linearly related to the quantity of scar at the PV ostium.