It seems what your doctor gave you is just rite cause it is what i got after consious rise of heart rate known as tachycardia. i consumed the medication for a stipulated period of time. but how i got complete relief was after opting for Meditation and Yoga. and also some lifestyle modifications. Yoga done in the form of pranayam is prety helpful. concentrate more on Meditation, it will relive you relax and also reduce your stress levels and ultimately controling your heart rate effectively.