Table 2:

Considerations for successful FIRM-guided ablation

- General	- Basket coverage (multiple positions ideally used) and careful map interpretation are the cornerstones of AF driver ablation.
	- Rotational and Focal Driver regions fluctuate but remain in spatially stable regions which are ablation targets.
	- Sources lie in 2-3 cm2 areas (1.5 X 1.5 cm).
	- FIRM sites lie between, i.e. are typically bounded by physical electrodes.
	- Given the size of each ablation lesion (>7 mm), one should bracket the driver between electrodes rather than define a precise ‘core coordinate’
- Right Atrial Sources	- Observed in one third of patients, paroxysmal as well as persistent AF (see figure 3)
	- Typically fewer in number than in left atrium
	- No stereotypical locations, but more likely in the free wall (where phrenic capture should be tested), septum and posterior wall.
	- Rarely at the superior vena cava or cavotricuspid isthmus.
- Left Atrial Sources	- Observed in nearly all patients.
	- Typically multiple (average of 2-3), with higher numbers in patients with more advanced disease (persistent-long-standing AF)
	- No stereotypical location, but 40-50% at sites covered by a typical wide area PV antral ablation