How effective are ablations for atrial fibrillations?

Not very effective. : Ablation for regular tachcardias such as supraventricular tachycardia or atrial fibrillation is very successful (>90%). Ablation for atrial fibrillation which is chaotic rhythm is either not successful or if initial success, the positive outcome is not sustained. In other words there is a high rate of recurrence.

Depends...: I'm going to assume you're 25 and have "paroxysmal" atrial fibrillation (afib some of the time, but not most of the time). In that case, an initial procedure using current techniques is 50-70% likely to leave you free of fibrillation. A second procedure if needed will increase that to 70-85%. Some next generation ablation techniques may give even better results than these.