a Novel Individualized Substrate Modification Approach for the Treatment of Long-standing Persistent Atrial Fibrillation

Overview

The purpose of this study is to compare effectiveness of two substrate modification approaches in long-standing persistent atrial fibrillation patients, and hypothesized that a substrate-based, individualized substrate modification (ISM)approach should be superior to traditional stepwise ablation(SA). To the best of investigator's knowledge, this was the first study to evaluate the "real" substrate by means of electro-anatomic mapping and to perform "true" substrate modification in long standing persistent atrial fibrillation ablation(LPAF).

Catheter ablation (CA) is highly effective for paroxysmal atrial fibrillation(AF), it is modestly effective for long standing persistent atrial fibrillation ablation(LPAF) even with complex or combined approaches, which is mainly attributed to the substrate underlying AF remodeling. Severity of atrial fibrosis is closely associated with clinical outcomes after CA for AF . The more atrial scars and fibrosis present, the lower the success rate for AF ablation. Patients with LPAF have many more areas with scars and fibrosis than those with paroxysmal AF or non-AF controls. The MRI delayed enhancement technique provides a non-interventional tool for evaluation of atrial fibrosis, however, it must be performed in sinus rhythm.Three-dimensional electro anatomic mapping has proven as accurate as MRI and can be performed easily during AF ablation, thus providing a good tool for evaluation of atrial substrate during LPAF ablation. Although electro-anatomic mapping provided a desirable surrogate for delayed enhancement MRI to define AF substrate, there was an important technical issue to be considered. There were no good techniques to predict a desirable tip-tissue contact before the contact force catheter was applied. A poor tip-tissue contact could render the results of voltage mapping less reliable. On the other hand, excessively high contact force could increase the risk of steam pop and cardiac perforation during ablation. Hence it was important to use the contact force catheter to perform substrate mapping and ablation.