Is a heart rate of 52 dangerous in a 71 year old woman?

My mother is 71 and not in very good shape. She is on medication for high blood pressure, high cholestral, inhaler for chronic bronchitis & many allergies, and is being treated for low platelets by a hematologist. Smoked for over 40 years (only quit 3 years ago). Gets absolutely no exercise. Was in to her primary doctor and had a bad EKG--is having an ultrasound at the hospital & more blood work tomorrow. He heart rate ranged between 52 and 54 on 2 different EKGs. The dr. called the hematologist and they decided to put her on Coumadin immediately. Have already made an appointment with a cardiologist next week. Do you think she has a blockage or is going to have a stroke? Just worried until I hear from the doctors.