I Just Turned 60. I Have Several Stents In My

I just turned 60. I have several stents in my heart. I have never had a heart attack, but since I have a family history of heart disease I am very aware of my body. When I can barely get up the steps, my cardiologist sends me off to get angioplasty test which ends up with putting in stents to clear arterial blockage. After each stent I feel as good as new. My first stent was 2006. In 2008 I had 2 more. In 2014 I had two more. In 2015 three of the prior tents grew over and new stents had to be inserted in them. I feel great, but in the last few days I feel a flutter in my upper left chest. At first I thought my cell phone was vibrating, but now it's constant. No pain or discomfort, just this flutter feeling. Any ideas?