I take metoprolol tartrate to control a non-sustained ventricular arrythmia (as per my cardiologist). I do not have atrial fibrillation nor do I have high blood pressure. I actually have more than one type of arrythmia. I have been on metoprolol (12.5mg×2) for 4 years. It works well for me (so far). Betablockers are often used to control arrythmias.