Left Atrial Anatomy in Patients Undergoing Ablation for Atrial Fibrillation

Citation : David Krum, MS, John Hare, BS, Carol Gilbert, RN, Indrajit Choudhuri, MD, Naoyo Mori, PhD, Jasbir Sra, MD

Background: Left atrial anatomy is highly variable, asymmetric, irregular and three-dimensionally unique. This variability can affect the outcome of atrial ablation. A catalog of anatomic varieties may aid patient selection and ablation approach and provide better tools for left atrial ablation.
Methods: We analyzed computed tomography scans from 514 patients undergoing left atrial ablation. Images were processed on Advantage Windows with CardEP™ software (GE Healthcare, Waukesha, WI). Measurements of pulmonary vein (PV) ostial size along the long and short axes were made using double oblique cuts, and area of the ostia was calculated.
Results: Low peak LAA emptying velocities (<40cm/s) were identified in 111 (24.7%) patients and LAA thrombus was identified in 3 patients (0.5%) despite having therapeutic INRs. The 3 patients with thrombus had LAA emptying velocities of 23, 29 and 31 cm/s. None of the remaining patients had a peri-procedural stroke. Patients with peak LAA emptying velocities <40cm/s or thrombus on TEE had significantly (p<0.05) higher CHA₂DS₂-VASc scores (1.7± 0.1 v’s 1.4±0.1), and were more likely to have impaired LVSF (odds ratio [95% CI]: 2.66 [1.52-4.66]), a LA diameter >4.6cm on TTE (2.40 [2.13-5.41]), or persistent AF (2.60 [1.63-4.14]) compared to those with a higher LAA velocity without thrombus.
Conclusions: More than 37% of patients have a left atrial anatomy other than 2 left and 2 right PVs. This data may help in designing approaches for left atrial ablation, tailoring the procedure to individual patients and improving ablation tools.