Hybrid solid-state SPECT/CT left atrial innervation imaging for identification of left atrial ganglionated plexi: Technique and validation in patients with atrial fibrillation

Background Ablating left atrial (LA) ganglionated plexi (GP), identified invasively by high-frequency stimulation (HFS) during pulmonary vein isolation (PVI), may reduce atrial fibrillation (AF) recurrence. I-123-metaiodobenzylguanidine (I-123-mIBG) solid-state SPECT LA innervation imaging (LAII) has the spatial resolution to detect LAGP non-invasively but this has never been demonstrated in clinical practice. Methods 20 prospective patients with paroxysmal AF scheduled for PVI underwent I-123-mIBG LAII. High-resolution tomograms, reconstructed where possible using cardiorespiratory gating, were co-registered with pre-PVI cardiac CT. Location and reader confidence (1 [low] to 3 [high]) in discrete I-123-mIBG LA uptake areas (DUAs) were recorded and correlated with HFS. Results A total of 73 DUAs were identified, of which 59 (81%) were HFS positive (HFS +). HFS + likelihood increased with reader confidence (92% [score 3]). 64% of HFS-negative DUAs occurred over the lateral and inferior LA. Cardiorespiratory gating reduced the number of DUAs per patient (4 vs 7, P = .001) but improved: HFS + predictive value (76% vs 49%); reader confidence (2 vs 1, P = .02); and inter-observer, intra-observer, and inter-study agreement (kappa = 0.84 vs 0.68; 0.82 vs 0.74; 0.64 vs 0.53 respectively). Conclusions I-123-mIBG SPECT/CT LAII accurately and reproducibly identifies GPs verified by HFS, particularly when reconstructed with cardiorespiratory gating.