An activation-repolarization time metric to predict localized regions of high susceptibility to reentry.

BACKGROUND Initiation of reentrant ventricular tachycardia (VT) involves complex interactions between front and tail of the activation wave. Recent experimental work has identified the time interval between S2 repolarization proximal to a line of functional block and S2 activation at the adjacent distal side as a critical determinant of reentry. OBJECTIVES We hypothesized that (1) an algorithm could be developed to generate a spatial map of this interval ("reentry vulnerability index" [RVI]), (2) this would accurately identify a site of reentry without the need to actually induce the arrhythmia, and (3) it would be possible to generate an RVI map in patients during routine clinical procedures. METHODS An algorithm was developed that calculated RVI between all pairs of electrodes within a given radius. RESULTS The algorithm successfully identified the region with increased susceptibility to reentry in an established Langendorff pig heart model and the site of reentry and rotor formation in an optically mapped sheep ventricular preparation and computational simulations. The feasibility of RVI mapping was evaluated during a clinical procedure by coregistering with cardiac anatomy and physiology of a patient undergoing VT ablation. CONCLUSION We developed an algorithm to calculate a reentry vulnerability index from intervals between local repolarization and activation. The algorithm accurately identified the region of reentry in 2 animal models of functional reentry. The clinical application was demonstrated in a patient with VT and identified the area of reentry without the need of inducing the arrhythmia.