Is 12.5 mg atenolol bid a good dose to keep a heart rate down below 100 beats/min at night?

Starting dose: Total of 25 mg in divided doses is a good starting dose. Can go up to 100mg a day. Are you having dizziness after atenolol started? I like the combination with a diuretic. Remember that lifestyle changes like weight reduction, exercise, low sodium/high potassium and magnesium/low fat diet, stop smoking and stress reduction technique can reduce your BP too. If hr high you may need to increase dose.