Thank you both for replying
I have a necklace that has the SOS emblem on the front and at the back it states my name and that I am on warafrin and that I have had Atrial Septal Defect closure. I do have a card but I don't often have it on me....... As for the horse riding my cardiologist has agreed that I can ride. He said he would normally advise against it but because I have been riding since I have been 5 years old and also I have had my horse for 10 years I would know my horse. However he has put restrictions on. That is that I cannot do show jumping or cross country, also no more lovely canters and gallops as If my horse should throw me in speed the impact would be a lot worse than in walk. This is because of the risk to a bleed in the head.
The fear I have is the what ifs but I have decided that I am going to be riding by the end of this month. I am also thinking of buying a INR machine as I think this would give me more of piece of mind over my INR.