The normal heart rate is 60-100 beats per minute at rest. When atrial fibrillation occurs, the heart rate can rise to 150 – 180 beats per minute, or higher. Even with normal heart function at the beginning, long lasting high heart rates can damage your heart, this condition is known as tachycardiomyopathy. If the attempt of restoring sinus rhythm is unsuccessful, it is of utmost importance to slow the heart rate.
It is very important to follow your doctor advice and take your medications as prescribed.