I've had these same signs. I've also been having heart trouble the last few years. I often see 9:11 when I look at the clock. You wouldn't believe the amount of signs I see about death. I think it's ansubconscious thing. I'm still quite young, in my 30s.
I've had a few NDE's...and they have all been pleasant and painless.
However, I just don't think most of us get signs of our death...both of my NDEs, were completely out of the blue. At either on, I could have been gone.
I think that part of the reasons I'm seeing so many signs is because Instill have somewhat of a fear of death...and that's why I'm seeing it. My fear isn't of the afterlife, it's leaving my children. They are not grown yet, and one is disabled, so he never will be. There's still things I want to see and do. Most of my life has been hard, so I just want ONE phase to be happy.
Most people whose time is up, do not see signs like we are seeing...it would cause too much anxiety. I've always noticed that people (not who take their own life) but people who seem to die randomly....are happiest leading up to their deaths. I don't know what it is...some kind of energy and etheric thing going on there. There usually no consciousnsign of death....just an inner peace with life, or sense of urgency to get things done....but not out of fear....out of excitement, like marking off a bucket list.
So, saying all this....And What I know personally about death, it's most likely stress and anxiety about your health, and what's in your future. So far, you have not been given a death sentence...and there are many many options for people with heart issues, and many many people, including my FIL, who have died and come back from heart troubles....and still living decades later, with a defibrillator, or surgery.
Try to relax, and be easy on your heart. Worrying, stress, etc will only make your mind go crazy, and cause undue stress. When it's your time to go....you won't know it. You will be here one second, and gone in the next. From my own experience, once your gone....you won't feel any more pain, physically, emotionally, mentally, etc. Death means your life sentence is over. It's actually more beautiful than you can imagine. Just imagine going back to your innocence of being a small child or baby, where anything is possible....and you know and feel nothing but love. Never let death scare you.
Be easy on yourself, and enjoy your life here....because it's so short. 100 years is nothing in the life span of infinity. Just pay attention to when your heart starts acting up most. Is it okay in the morning and gets worse through out the day? Are you sleeping good, are you eating healthy, drinking lots of water, dealing with stress, worry, anxiety in a balanced way? Do you laugh and smile, read, socialize, get out of the house or pursue artistic pursuits? Do you smoke, drink, eat lots of unhealthy foods, worry too much....etc etc etc. Those are all things you can control and can contribute to how your heart functions. Take your mind to happy things, happy people, happy places, and your heart will follow.