Inverse solution electrocardiographic mapping of epicardial pacing correlates with three-dimensional electroanatomic mapping

We hypothesized that the calculation of epicardial potentials from body-surface potential maps (BSPMs) could aid ablation of ventricular tachycardia (VT). BSPMs were recorded during epicardial catheter mapping and pacing in 2 patients. Single-beat epicardial maps were calculated by inverse solution using customized torso/cardiac geometry, discretized from a CT scan. During pacing from 48 epicardial sites, we observed stimulus-QRS delay (Stim-QRS) of 27 plusmn 7 ms and a difference between known pacing locations and calculated sites of earliest potential minima of 1.6 plusmn 1.4 cm. Pacing in scar and scar-border zones had longer Stim-QRS delay (51 plusmn 24 ms and 35 plusmn 23 ms, respectively, p=0.004), and greater distances between known pacing sites and known locations (3.0 plusmn 1.6 cm and 4.6 plusmn 2.0 cm, respectively, p=0.0004). BSPM with inverse solution mapping can identify sites of earliest epicardial activation and thus could have clinical utility.

1. Introduction

Prior myocardial infarction is the most common cause of sustained ventricular tachycardia (VT). Management options include implantable defibrillators (ICDs), antiarrhythmic drugs, arrhythmia surgery, and catheter ablation [1], [2]. Although ICDs reduce mortality, they do not prevent recurrent VT, which occurs frequently in ICD recipients [3]–[5]. Catheter ablation has a role as an alternative or adjunct to pharmacologic therapy to prevent recurrent VT [6]. One such technique involves identification of the infarct substrate with pace-mapping around the edges of the infarcted myocardium [7], [8] until a match for QRS morphology of VT is seen. An intuitive interpretation of the surface ECG is required for this approach, which is often challenging. A technique to rapidly identify the scar exit sites of VT circuits could facilitate catheter ablation and direct more detailed point-by-point mapping. An endocardial array is available for this purpose, but is costly and requires the introduction of a large intracardiac balloon-mounted array [9].