Hello Robin and thank you for using HCM.I carefully read your question and I understand your concealer. I will try to give you my opinion. In fact, as you describe your mom has a complicated heart history. As she had done a heart attach and it is a confirmed ischemic heart disease corrected with stents it is mandatory to have a slow heart rate. It is our goal when we treat ischemic heart disease to have slow heart rates. As the heart has problems with normal blood supply throught the coronary artery it is mandatory to lower the heart work. So, through medications we lower the frequency, the blood pressure to makes thinks easier for the suffering heart. So you don t have nothing to worry for these frequency. The frequency between 45-50 its quite normal. I will like to advise you that only if she feels fatigue, if she experience syncope or chest pains and a heart beat below 40 she should seek medical attention. So, don t worry for the moment because every think is quite normal and what we desire in her situation. Hope I was helpful. BEST REGARDS.