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.

Inclusion Criteria:

1. Patients with permanent AF/persistent AF (in AF)

2. Patients with NYHA Class II -IVa HF symptoms

3. Guideline driven medical therapy (GDMT) for HF for at least 3 months:

   • for those < 75 years of age with an NT-proBNP of ≥ 600 ng/L
   • for those ≥ 75 years of age with an NT-proBNP ≥ 900 ng/L, or ≥ 600 ng/L if the patient has had a HF hospitalization within 1 year

Exclusion Criteria:

1. In hospital patients needing intensive care or intravenous inotropic agent in the last 4 days
2. Patients with a life expectancy of ≤ 1 year from non-cardiac cause or anticipating a transplant within 1 year
3. Acute coronary syndrome <4 weeks or coronary revascularization <3months
4. Unable or unwilling to provide informed consent
5. Uncorrected primary valvular disease or prosthetic tricuspid valve
6. Restrictive, hypertrophic, or irreversible form of cardiomyopathy
7. Severe pulmonary diseases requiring oxygenation
8. Patients with a known history of WHO Class I pulmonary hypertension (PH) which includes PH associated with CVD, collagen vascular disease, congenital shunts, cirrhosis and portal hypertension, HIV, hemoglobinopathies, schistosomiasis or drug-associated PH as well as those with high suspicion of irreversible pulmonary hypertension
9. Patients enrolled in competitive clinical trials that will affect the objectives of this study
10. Existing CRT/BiVP
11. Patients who are pregnant
12. Guideline indication for CRT
13. More than 20% pacing with an existing pacemaker
14. Severe mobility limitations (ex. wheelchair bound and severe neurological conditions that limit mobility)