The Effect of Beta-blocker on Chronotropic Response and Cardiorespiratory Fitness in Patients With Atrial Fibrillation

The Effect of Beta-blocker on Chronotropic Response and Cardiorespiratory Fitness in Patients With Atrial Fibrillation: a Crossover Randomized Controlled Trial.

This is a prospective study to evaluate changes in exercise capacity and chronotropic response to exercise before and after beta-blocker dosage reduction in patients with atrial fibrillation (AF).

Rate control therapy is the first-line treatment for atrial fibrillation (AF). Resting heart rate(HR) is the treatment target of rate control therapy in current clinical practice; However, the optimal value for resting heart rate in AF remained unclear. Beta-blocker(BB) is widely used as rate-control agent. It is concerned that excessive use of BB might lead to a negative effect on exercise capacity in patients with AF. The aim of this study is to explore the effect of Beta-blocker on hemodynamic parameters and peak oxygen uptake during cardiopulmonary exercise test (CPET).

Inclusion Criteria:

1. > 20 years of age.
2. Clinically stable patients with persistent atrial fibrillation using beta-blocker as rate-control agent without dosage adjustment for at least 3 months.
3. Resting heart rate < 80 bpm.
4. Left ventricular ejection fraction > 50%.

Exclusion Criteria:

1. Beta-blocker usage due to indications other than rate control for atrial fibrillation.
2. Inability to perform a cardiopulmonary exercise testing.
3. Presence of contraindications for cardiopulmonary exercise testing according to the American College of Sports Medicine's Guidelines for Exercise Testing and Prescription.
4. Patients with implantable cardioverter defibrillator or pacemaker.
5. Pregnancy.
6. Inability to provide informed consent.