I Am 72 Yrs Old I Am A Cadiac Patient,

I am 72 yrs old I am a Cadiac patient, I had one blockage in my heart & I make Engio Plast In the year 2009. Now I am OK. but when I try go up by walking or stare case then I feel small pain in chest , then I take rest for 10/15 minutes the pain goes away .What can I do now/ Thank you sir.