The procedure can last between one to five hours, depending on individual conditions:

 

• the number of ectopic sources in the atrial tissue (outside the pulmonary veins) which requires more mapping time;

• linear ablation of atrial tissue substrate, determined by cardiac thickness along its length, varies from one patient to another and cannot be precisely evaluated by pre-ablation imaging.

 

 

The end-point of the procedure is achieving local block in all targeted structures (veins and isthmuses). In addition, inability to induce sustained AF despite multiple pacing maneuvers is obtained in 90 % of cases of paroxysmal AF.

 

In 25 % of subjects a second procedure may be needed within 3-5 days for complementary ablation. This may due either to partial recovery of ablated tissue or to secondary revealed sources. In difficult cases of multiple or unmappable ectopic foci, a second linear ablation may be required in the left atrium. In chronic AF, which is associated with widespread atrial abnormalities, reablation is needed in 45 % of cases to eliminate atrial tachycardia in remnants of abnormal tissue.