Raquel,
Many people, doctors included, do not know much about warfarin and are afraid of it. Therefore they blame anything that they can on it. If he had an INR of 2.6 it is extremely unlikely that he is throwing little clots. The rate of any type of clot for anybody with any condition at any INR is less than 1 per 100 patient years. Throwing little clots with an INR of 2.6 is about as likely as a Clydesdale winning the Kentucky Derby. Throwing more medication (Aspirin and Plavix) at him when the tests we are all negative doesn't sound like a good answer. I'm not an expert on psychology but I've heard this story over and over from people who are depressed. Depression is a normal reaction to valve replacement according to those who are on this site. The heart stopping, double vision, his age, the fact that he is male and not being willing to get on here and discuss it all point in this direction. Eventually he will get overmedicated to the point that something will have to be done. Ignore the amount of vitamin K in soy unless he consumes heroic quantities of it on some days and not others. It is just another smokescreen.