The course of the sinus node artery and its impact on achieving linear block at the left atrial roof in patients with persistent atrial fibrillation.

BACKGROUND

Linear block at the left atrial (LA) roof may be challenging in some patients undergoing an ablation procedure for atrial fibrillation.

OBJECTIVE

To identify factors that may influence the likelihood of achieving roof block.

METHODS

Seventy-four patients (61 ± 10 years; 59 men [80%); LA diameter, 46 ± 6 mm; ejection fraction 0.55 ± 0.10) underwent linear ablation at the LA roof for persistent atrial fibrillation. The morphology of the roof and its anatomical relationship to adjacent structures were analyzed on a preprocedure computed tomography scan.

RESULTS

Complete block along the LA roof was achieved in 61 of the 74 patients (82%). There was no significant difference in the myocardial thickness, length, or other morphological aspects of the LA roof between patients with and without complete block. The sinus node artery (SNA) originated from the right coronary artery in 52 patients (70%) and the left circumflex artery in 22 patients (30%). The prevalence of a left SNA (from the circumflex) among patients with and without linear block at the roof was 21% and 69%, respectively (P = .001). On multivariate analysis, a left SNA was the only independent predictor of incomplete conduction block at the LA roof (odds ratio 6.8; 95% confidence interval 1.7-28; P = .007).

CONCLUSIONS

A left SNA identifies patients in whom conduction block at the roof is more difficult to achieve. A left SNA may act as an epicardial heat sink, preventing adequate heating of the LA roof during linear ablation.