Atrial Fibrillation: Chronic Beta-blocker Use Versus As-needed Rate Control Guided by Implantable Cardiac Monitor

The goal of this study is to test the feasibility of guiding as-needed pharmacological rate control of atrial fibrillation (AF) by implantable cardiac monitors and to assess the impact of continuous beta-blocker therapy versus as-needed rate control on the following outcomes:

(1) exercise capacity, (2) AF burden, (3) symptomatic heart failure, (4) biomarker assessment of cardiac filling pressures and cardio-metabolic health, and (5) quality of life in patients with atrial fibrillation and stage II or III heart failure with preserved ejection fraction.

Patients ≥ 18 years of age with paroxysmal or persistent AF who have an implantable cardiac monitor (either loop recorder or pacemaker) and who are receiving daily beta-blocker therapy will be screened for meeting the inclusion/exclusion criteria.

Trial participants will then be randomized into the daily beta-blocker or as-needed pharmacological rate control.

At baseline and six months trial participants will undergo assessment of the following measures:

* Assessment of Quality of life using the Minnesota Living with Heart Failure Questionnaire and the Atrial Fibrillation Effect on Quality of life Questionnaire.
* Blood draw
* Cardiopulmonary exercise test, 6 Minute Walk Test and average daily activity level via integrated accelerometer of the implantable cardiac monitor (if available).
* Assessment of AF burden

Study participants may opt into long-term follow up visits at 12, 18 and 24 months.

Chart review will continue for up to 4 years after enrollment for the purpose of monitoring clinical endpoints:

* Heart failure events (diuretic drug change, emergency room visit, hospitalization)
* AF events (hospitalization, emergency room visit, cardioversion, antiarrhythmic medication initiation)
* Stroke or transient ischemic attack
* Myocardial infarction

Eligibility Criteria:
Inclusion Criteria:

* Paroxysmal or persistent AF diagnosed in the past 4 weeks or longer
* Implantable cardiac monitor (either loop recorder or pacemaker)
* Current treatment with greater than minimum doses of beta-blockers OR any beta-blocker with resting sinus rhythm heart rate \< 75 bpm (documented on EKG in the last 6 months OR at enrollment visit)
* Left ventricular ejection fraction ≥ 50% (reported on echocardiogram within the past 48 months)
* Echocardiographic evidence of structural changes consistent with HFpEF defined by (1) left ventricular hypertrophy (septal or posterior wall thickness \> 10mm) OR (2) left atrial enlargement OR (3) diastolic dysfunction.

Exclusion Criteria:

* Long-standing persistent or permanent atrial fibrillation (Long-standing persistent AF is defined as continuous AF of \> 12 months duration. Permanent AF is defined as AF accepted by the patient and physician and no further attempts to restore/maintain sinus rhythm will be undertaken).
* Echocardiographic evidence of left ventricular dilation (defined as left ventricular end diastolic volume (LVEDV) index ≥ 80ml/m2 as determined by echocardiogram within the past 48 months.
* Documentation in the electronic medical record suggesting a life expectancy less than 12 months

Minimum dosage of beta-blocker therapy to meet enrollment criterion:

Metoprolol tartrate 25mg twice daily, Metoprolol succinate 50mg daily, Carvedilol 12.5mg daily, Bisoprolol 5mg twice daily, Nebivolol 5mg daily, Atenolol 50mg daily, Labetalol 100mg twice daily, Propranolol 40mg twice daily