3D mapping quest: How far can we see with recent advances in 3D mapping?

Recent advances in three-dimensional (3D) ultra-high-density mapping systems have uncovered previously unknown mechanisms underlying various arrhythmias. This clinical review, titled "3D Mapping Quest," focuses on the recently uncovered mechanisms of four types of arrhythmias. (1) To elucidate the precise mechanisms underlying atrial fibrillation (AF), ultra-high-density mapping with adequate spatial and temporal resolution is essential. Various mapping systems have been employed to investigate the chaotic activation during AF. The question remains: Is the AF driver characterized by focal activation or rotational activation? A novel mapping strategy is expected to provide the answer. (2) In atrioventricular nodal reentrant tachycardia (AVNRTs), 3D mapping revealed that the pivot point of activation at the lower end of a functional block line extending vertically downward from the His-bundle area, or a fractionated potential observed during AVNRT, can be targeted for slow pathway ablation. Either approach may prevent unnecessary radiofrequency applications while maintaining the success rate. (3) In premature ventricular contractions originating from the left ventricular summit, 3D mapping has enabled precise identification of the optimal endocardial ablation sites. By performing long-duration ablation at these optimal endocardial sites, the ablation outcomes have improved. (4) In scar-related reentrant ventricular tachycardia (VT), substrate mapping focusing on wavefront discontinuity has allowed for the identification of specific ablation targets within the broad scar. High-density VT activation mapping has revealed the complexity of the circuit structure, such as the 3D VT circuit. The VT circuit delineation on the cardiac surface is conceptualized as a cross-section of a hyperboloid model. Thus, it is anticipated that integrating histological and electrophysiological insights with advanced ultra-high-density mapping technologies will further facilitate a comprehensive understanding of the mechanisms.