The purpose of this study is to compare the effect of metoprolol, verapamil, diltiazem and carvedilol on ventricular rate, working capacity and quality of life in patients with chronic atrial fibrillation.

This is a randomised, single blinded, cross-over study comparing the efficacy of metoprolol 100 mg o.d., verapamil 240 mg o.d., diltiazem 360 mg o.d. and carvedilol 25 mg o.d. in reducing ventricular rate in atrial fibrillation. A total of 60 patients will be included, with a minimum of 20 women.Patients will receive each of the drug regimens in a random sequence. Each regimen will be administered for 3 weeks, ensuring that steady-state drug concentration will be attained and to provide an adequate washout of the previous treatment. Following each regimen, exercise ECG and Holter registration will be performed and patients will undergo laboratory evaluation and complete QoL-forms. They will then be started on the next randomly assigned treatment regimen, until the entire sequence of treatment schedules is completed.

Inclusion Criteria:

• Persistent or permanent atrial fibrillation with ventricular rate > 80/min at rest and/or > 100/min average at daytime.
• Male or female, age > 18.

Exclusion Criteria:

• Hypersensitivity or contraindication to metoprolol, verapamil, diltiazem or carvedilol.
• Coronary heart disease or heart failure
• Systolic blood pressure < 100 mmHg
• AV-conduction disturbance
• Severe hepatic or renal dysfunction
• Thyrotoxicosis
• Ongoing treatment with Digitalis
• Pregnancy or lactation