Dropping down on the street is a totally different scenario to allowing someone who is clearly terminally ill to die in a controlled environment in a hospital bed with medical staff available.
I think I understand your wish to have a choice, but could I suggest that if I saw someone having a heart attack in a public place, there would be no choice for me but to do my utmost to save that person, regardless. Most with paramedic/first aid training would instinctively regard it their duty to save life, and to stand around and watch someone die knowing they could have at least tried to save them is not an option. I, for one, would not forgive myself for walking away from someone who had a chance to survive. Perhaps consider it from this perspective also? Again, very best wishes, I don't question your right to a choice- but there is no choice for those trained to save life.