Question hi im a 37 male my history, i have sinus tachardia and take 100 mg of atenenol daily i have had 2 episodes of lone afib in october 2012 and then in october 2013. i woke up with chest pain dead center it comes and goes. it is like a pericing pain, its got me worried . my heart rate and blood pressure is fine. i had all the heart tests in the last 5 years. everything is fine and we never found the cause of the lone afib . I dont recall doing anything to sprain or strain myself. what do you think it is.