The objective of this trial is to show the therapeutic efficacy of the preventive pacing therapies of the Selection 9000 and Vitatron T70 DR pacemakers, dedicated to handle atrial fibrillation (AF). Two new algorithms (post-AF response and ventricular rate stabilization [VRS]) will be assessed in a combined pathway, compared to a control group. The efficacy of the overall available therapies to prevent AF and its symptoms will then be assessed also.