Introduction:
Drivers have been shown in animal models of AF as regions where fibrillation rate and organization step-down to surrounding regions. However, sites of interest in human AF have typically been identified by high AF rate alone or by complex fractionated atrial electrograms (CFAE), which may explain the suboptimal ablation success at these sites.
Hypothesis:
We hypothesized that a potential driver of human AF should exhibit high rate and organization with ‘local control’, i.e. centrifugal step-down to neighboring sites.
Methods:
In 17 patients (age 63±9 y; 9 persistent) prior to AF ablation, we analyzed AF rate and organization
simultaneously
between 64 left atrial (LA) basket electrodes and electrodes in pulmonary veins (PV), coronary sinus (CS) and right atrium. At each electrode, we spectrally measured AF cycle length (CL) and organization (PAR), and visually quantified fractionation for 8.192 second AF epochs.
Results:
We analyzed 6687 electrode-epochs. Sites of rapid AF were ubiquitous, but met criteria for a single driver in only 7 patients. Unlike sites of rapid AF rate alone which were often mixed with sites of both high and low rate,
potential drivers
showed an organized and step-wise fall in rate and organization with distance from that site (p=0.005) in persistent and paroxysmal AF. In persistent AF, CL rose from 138±25 ms at driver sites (n=5) to 194±10 ms at neighbors (p<0.05) and organization fell in a parallel organized fashion with distance (p<0.05). Drivers lay at CS and LA roof but not PVs. In paroxysmal AF, 4 of 6 drivers lay near or within PVs. Notably, only one third of drivers were at or adjacent to regions showing fractionation (CFAE).
Conclusions:
Simultaneous multi-site analysis identified a potential AF driver with local control of AF rate and organization in 41% of patients, lying within or near PVs in paroxysmal but not persistent AF, and relating inconsistently to electrogram fractionation. Future work should identify multiple co-existing drivers, and determine if ablating such sites improves outcome.
