Is It Safe To Use Viagra To Improve Sex Drive?

sir, i am 39 years old and last year i have done angioplasty and two stent is placed in my heart due to mild attack.I had more personal family problem and also used to get tense more.But,there is no family and health history...i dont have sugar, bp, chlostrol. But i got into mild attack. Now i am under medication. But, i want to have free sex without any fear. I have preejaculation and not having sex more time. In this condition shall i use any tablet to improve my sex like viagra.? so far i never used anything for having more time sex.Can u please suggest me in this regd.?