atrial fibrillation
"I was having regular episodes of atrial fibrillation.  Often 2-3 per day, lasting from a few minutes to several hours.  Started on 100mg flecainide twice a day.  Episodes stopped, but suffered from muscle soreness and felt tired all the time.  Doctor dropped the dosage to 50mg twice a day.  Symptoms lessened and have not had an episode in 5 years."