How often do cardiac ablation surgeries result in complications requiring pacemakers implantation?

Nodal ablation: In ablating cardiac dysrhythmias, the ablation catheters can sometimes affect the conduction to or from the atrio-venticular node (avn). This is an important regulator of heart rate and if affected the reslutant 'escape rhythm' may be too slow to accomadte normal activity; thus a pacemaker is required. In some conditions, like atrial fibrillation, the goal may be avn ablation and pacemaker implant.

It depends: It depends on the ablation type: almost never for wpw, atrial fibrillation/flutter or ventricular tachycardia; 1% or less for avnrt (atrioventricular nodal reentry tachycardia). In avnrt, there is an extra 'lane' in the av node that conducts electrical impulses leading to tachycardia and the ablation can unintentionally damage the whole av node resulting in heart block and need for pacemaker.

It depends: There are certain procedures in very specific patients where that risk is high, but generally the risk is much less than 1%.