Suggest Precautions To Be Taken To Avoid Heart Stroke In Person Having Leakage In Valves

my sister was just told by a doctor that she has a stiff heart and 2 valves that leak. She is in good shape except now she is very worried about this , She is 77 and now is very worried about this. she is worried about having a heart attack so what should she do to keep from having a stroke or heart attack?