Left Variant Atypical Atrioventricular Nodal Reentrant Tachycardia Associated With Situs Inversus Totalis

BACKGROUND: Left variant type slow-slow atrioventricular nodal reentrant tachycardia (AVNRT) is rare, and its occurrence in patients with situs inversus totalis has not been previously reported. CASE SUMMARY: A patient with situs inversus totalis presented with recurrent supraventricular tachycardia. Electrophysiological study excluded atrioventricular reentrant tachycardia and atrial tachycardia, supporting a diagnosis of left variant slow-slow AVNRT. Catheter ablation targeting the left atrial slow pathway at the inferolateral mitral annulus was performed using cardiac computed tomography and high-density electroanatomical mapping. Tachycardia was terminated with a single radiofrequency application and was no longer inducible. DISCUSSION: Catheter ablation in patients with situs inversus is technically challenging because of mirror-image anatomy, but advanced imaging and electroanatomical mapping allow accurate localization of the arrhythmogenic substrate and safe ablation. TAKE-HOME MESSAGES: Left variant slow-slow AVNRT can occur in patients with situs inversus totalis. Advanced imaging and electroanatomical mapping facilitate safe ablation despite anatomical complexity.