After heart attack
pumping of heart becomes weak if there is heart muscle damage which he go 4 years back. I hope he must be under medication and life style modification. If heart is treated with angioplasty
with stents ( ? 25 to 30 it can not be true may be typographical mistake) but if heart rate
is irregular a Holter monitorig may be advised and can be analysed to decide about AICD ( Automated Implanteble cardio defibrilator) wich saves patient from sudden death.Also some times to improve Ejection Fraction
of heart Synchronization device is implanted let your cardiologist decide it I may add these therapy are costly if no problem go for it.