This trial will compare two management strategies for HF patients with Atrial Fibrillation. The active control group will undergo BiV pacing, followed by an AV node ablation. The experimental group will undergo LBBAP, followed by an AV node ablation.

This is a prospective, randomized, double blind, control trial with follow up visits at 6- and 12-months following randomization. Patients will be randomized in a 1:1 allocation to either the control group [optimal medical therapy (OMT) + CRT + ANVA] or the treatment group [OMT + LBBAP + ANVA]. Randomization will be stratified by site and LVEF. In each group, the patient will undergo the pacing procedure (CRT or LBBAP) within 10 working days of randomization. They will be assessed by a physician one week after the CRT procedure, and if eligible, they will undergo an AVNA within 1-4 weeks. Success of these treatment plans will be evaluated primarily based on the change in NT-proBNP from baseline to 6- and 12-month follow ups. At baseline and follow up visits study staff and physicians will collect participants' medical history, complete a Physical Exam and an NYHA Class Assessment, a medication assessment, and a 6 Minute Walk Test. Participants will also be asked to complete Quality of Life Questionnaires (Minnesota Living with Heart Failure Questionnaire (MLHFQ) score, KCCQ and EQ-5D-5L), have an ECG and TTE performed if they have not had one performed recently, non- invasive hemodynamic measurements (if available), and complete routine bloodwork and an NT-proBNP test. The adequacy of HF treatment will be assessed clinically, and medications optimized and recorded. Device diagnostics will be assessed and recorded as to whether there are arrhythmias and to determine the appropriateness of device programming. Secondary study outcomes include QoL scores (MLHFQ, KCCQ and EQ-5D), as well as 6MWT distance, and change in echocardiogram parameters (including change in LVESV index from baseline, change in global longitudinal LV systolic strain from baseline, and change in LVEF from baseline at 6-month and 12-month followup). Secondary outcomes also include radiation exposure between LBBAP and CRT, feasibility of achieving conduction system pacing with LBBAP compared to CRT, and acute and long-term hemodynamic change due to either CRT or LBBAP (i.e., non-invasive hemodynamic measurements before and after AV node ablation including systolic BP, diastolic BP, cardiac output, stroke volume, total peripheral resistance, and pulse pressure).

Inclusion Criteria:

1. Patients with atrial fibrillation (AF) where AVNA is being considered with or without a pacemaker

   1. Are on optimal heart failure therapies for ≥4 weeks
   2. NYHA class I-IVa

2. Patients deemed not appropriate for rhythm control strategy (only for rate control strategy).

   1. Failed Ablation (≥1 failed ablation attempt)
   2. Refractory or intolerant to Antiarrhythmic drugs AADs or rate control medications
   3. Patient choice not to have rhythm control strategies
   4. Being considered for AVNA

3. Patients with baseline NT-proBNP>600 or >400 if HF hospitalization within 12 months.

Exclusion Criteria:

1. In-hospital patients with acute cardiac or non-cardiac illness that requires intensive care
2. Acute coronary syndrome (including MI) or Coronary revascularization (CABG or PCI) <3 months
3. Uncorrected or uncorrectable primary moderate to severe valvular disease
4. TAVI < 3 months
5. Restrictive, or reversible form of cardiomyopathy, cardiac amyloidosis
6. Severe primary pulmonary disease such as cor pulmonale, irreversible lung disease requiring inhalers, oxygen supplementation
7. Pulmonary hypertension (Mean pulmonary pressure is ≥35 mm Hg)
8. Patients with a life expectancy of less than one year from non-cardiac cause
9. Patients included in other clinical trials that will affect the objectives of this study or have competing interests
10. Those unable or unwilling to provide informed consent unless supported by legal power of attorney
11. Active malignancy with likelihood of survival <1 year
12. NYHA class IVb