Focal Rotor/Driver Ablation for Atrial Fibrillation: a Dream Come True?

Abstract

The success of catheter ablation of atrial fibrillation (AF) remains modest despite the use of a variety of techniques, because the real target remains elusive. Even the endpoint of AF ablation is still under debate. It is not yet known whether isolation of the pulmonary veins (PVI), currently having a reproducible modest success rate when performed at the antrum and guided by electrophysiological mapping, is what is needed or additional foci should be routinely targeted. Some investigators have suggested that it is the ganglionated plexi (GPs) that mostly provide the triggers to the pulmonary veins, and GPs should be the primary targets during ablation. Others have focused on ablation of complex-fractionated atrial electrograms (CFAEs) claiming successful outcome; some have combined PVI with ablation of CFAEs. In cases of persistent AF, additional ablation lines and/or posterior atrial wall debulking have been applied to enhance the success rate of the procedure. Until recently, no focal ablation was ever reported to have any success in this patient population.

Recently, Narayan et al devised an optical computational approach and mapped localized electrical rotors and focal impulse sources in 49 patients with AF. Patients with persistent AF (n=30) had more sources than those with paroxysmal AF (2.1±1.0 vs 1.5±0.8, P=0.02), related to shorter cycle length (163±19 ms vs 187±25 ms, P<0.001). The majority of sources were found in the left atrium and only about a quarter of sources were localized in the right atrium. In a subsequent case report, the authors presented a patient with persistent AF who failed prior left atrial radiofrequency Maze and endocardial ablation procedures. Use of this novel computational mapping disclosed one AF rotor in the right atrium and another in the left atrium. Brief 3–5-minute ablation applications at each rotor terminated AF, which remained noninducible on testing, while no AF recurrence was reported over the next 6 months. In another study by the same group, the investigators localized rotors or focal sources (mean 2.1 sources) in 98 (97%) of 101 patients with sustained AF and then proceeded with ablation aiming at these targets. This novel approach with focal impulse and rotor modulation (FIRM) was applied in 36 patients and compared with conventional ablation performed in the other 71 patients... (excerpt)