Study for Atrial Fibrillation Reduction (SAFARI)

Inclusion Criteria: * Subjects with a slow heartbeat who are in need of dual chamber pacing (pacing in both the atrium and ventricle). * Subjects who have experienced at least two episodes of rapid heart beats three months prior to enrollment. Exclusion Criteria: * Subjects who have a history of permanent (chronic) or persistent (non self-terminating) atrial fibrillation. * Subjects with atrial fibrillation due to reversible cause, (e.g. thyroid disease, pericarditis, post-surgery, alcohol abuse). * Subjects with a history of one or more cardioversions (changing an abnormal heart rhythm into a normal one by either using medication or by the application of an electric shock) six months prior to enrollment.