Has anyone had a heart attack or close to someone while they have?

So im now up to 5 women in my life that have passed from a heart attack. Only two were family members and I wasn't with any of them when it happened. My question is what did it feel like before or what have you been told? All 5 of these ladies passed suddenly without much warning other than one I was told didn't feel well all day, but not bad enough for the e.r. This scares me so bad because it just seems like they just went so fast, that even if they would have known what was happening could they have even been saved? What were the signs if there were any? What did you/they feel. Where there health factors before? Thank you in advance im just an anxious person.