Are drivers recurring or ephemeral? observations from serial mapping of persistent atrial fibrillation.

Abstract

Rotational re-entries and ectopic foci, or 'drivers', are proposed mechanisms for persistent atrial fibrillation (persAF), but driver-based interventions have had mixed success in clinical trials. Selective targeting of drivers with multi-month stability may improve these interventions, but no prior work has investigated whether drivers can be stable on such a long timescale. We hypothesized that drivers could recur even several months after initial observation. We performed serial electrophysiology studies on paced canines (n = 18, 27-35 kg) at 1-, 3-, and 6 months post-initiation of continual persAF. Using a high-density 64-electrode catheter, we captured endocardial electrograms in the left atrium (LA) and right atrium (RA) to determine the presence of drivers at each major anatomical site. We defined drivers that were repeatedly observed across consecutive studies to be recurrent. The mean probability that any driver would recur was 66% (LA: 73%, RA: 41%). We also found evidence of 'multi-recurring' drivers, i.e. those seen in all three studies. Multi-recurring drivers constituted 53% of initially observed drivers with at least one found in 92% of animals, and we found more multi-recurring drivers per animal than predicted by random chance (2.6 ± 1.5 vs. 1.2 ± 1.1, P < 0.001). Driver sites showed more enhancement than non-drivers during late gadolinium enhancement-magnetic resonance imaging (P = 0.04), but we observed no relationship between enhancement and driver recurrence type. We observed recurring drivers over a 6-month period at fixed locations, confirming our hypothesis. We also found drivers to be associated with fibrosis, implying a structural basis.