Pulmonary vein isolation in patients with paroxysmal atrial fibrillation is associated with regional defects in cardiac sympathetic activity

Objectives The activity of the sympathetic nervous system may play a key role in the development of atrial fibrillation (AF). Circumferential pulmonary vein isolation (PVI) is a modern AF management, yielding a success rate of about 70%. The mechanisms, by which AF relapses post PVI are triggered are still unknown. We hypothesized that PVI is associated with changes of cardiac sympathetic activity.

Methods 16 patients with paroxysmal AF underwent cardiac Iodine-123-meta-iodobenzylguanidine (mIBG) imaging before and 4 weeks after PVI. Planar images and SPECT/CT scans of the heart were performed 15 minutes and 4 hours after mIBG injection. Consecutive scans were analysed retrospectively by analysis of the heart to mediastinum (H/M) ratio and regional myocardial uptake.

Results The late H/M ratio did not change significantly before and after PVI (2.9±0.5 and 2.7±0.6, p=0.53). However, 4 out of 16 patients (25%) showed regional deficits already before PVI affecting the inferior lateral wall. After PVI, regional deficits were present in 10 patients (62.5%) including the 4 patients with pre-existing deficits. Newly emerging deficits post PVI were again localized in the inferior lateral wall (4 patients) and the inferior wall (2 patients). 4 (40%) of these suffered from an early recurrence of AF. Only one of the 6 patients (16.7%) without a detectable regional deficit had an early recurrence of AF.

Conclusions A significant number of patients with paroxysmal AF show regional sympathetic cardiac innervation deficits particularly after PVI. Defects are mainly observed in the inferior lateral wall. However, it is yet unclear whether the observed defects arise from an atrophy of sympathetic nerve plexus due to PVI or whether they can be attributed to a reduction of AF burden post PVI