Typical slow-fast AV nodal reentrant tachycardia (AVNRT) catheter ablation (CA) of slow pathway (SP) within right-sided triangle of Koch is the golden standard of the procedure. There are, however, rare (1-2%) cases of left-sided AV connections that require different approach to modify the reentry circuit and ablate SP. [1-3] We report a case of slow-fast AVNRT refractory to medical therapy and standard right-sided ablation. Retrograde zero-fluoroscopy (ZF) mapping of septal mitral annulus and left-sided applications achieve noninducibility and no-recurrences. To our knowledge this is the first case report of zero-fluoroscopy ablation of left septal slow-fast AVNRT. Moreover, use of ZF approach for routine, daily practice without intracardiac echocardiography requires expertise in retrograde mapping within mitral annulus substrate.