Second ER visit this year.

Not a doctor or pre-med or anything, but just for curiosity sake, how good of shape are you in? Physically speaking. Not sure if this is the case with you, but if you're overweight you should really consider taking up some physical activity to shed a few pounds and take any excess strain off of your heart. From personal experience this has worked wonders for me and has always been a place of concern given all of the heart conditions that run in my family.

Some regular exercising and heart conscious eating would really help your case, regardless of whether or not you're overweight, really. Also, a tablespoon of Olive Oil a day since it has some really good fats in it has been linked to being beneficial on the heart.