Atrial fibrillation (AF) is an irregular heartbeat that can cause symptoms of skipped beats, shortness of breath, stroke, or in some cases fluid in the lungs or legs. Treating AF is mostly to do with slowing the heart rate down so that the heart can get a chance to regain some energy. In some cases, slowing the heart rate is not easy to achieve as some patients find it difficult to tolerate medications and suffer side effects from these treatments. In these instances, there might be a possibility to permanently control the heart rate by implanting a pacemaker in the heart and intentionally damaging a regulatory region of the heart called the atrioventricular (AV) node. Damaging the AV node by a procedure called ablation results in the AF not being able to influence the bottom chambers (the ventricles) resulting in a slow rhythm. Therefore, if a pacemaker is implanted then the heart rate can be completely regulated by the pacemaker. A complex pacemaker that stimulates both the right and left ventricles simultaneously (BiVP) has been used for the last decade prior to AV node ablation. More recently, a technique has been designed to reduce the number of leads in the heart, reduce procedure time and have a similar effect on the heart called Conduction System Pacing (CSP). There is not enough existing evidence to show that a pace and ablate strategy is superior to optimal medical therapy. We intend to compare the efficacy of CSP with AV node ablation to optimal medical therapy for treating AF.