Now. I could be wrong, I'm not a doctor, but from memory, the MoA of ASA is to block COX 1/2. In the platelets, inhibition of COX1 chokes off the production of a prostaglandin necessary for platelet aggregation into a clot. This really wouldn't do all that much for an existing clot, except, I suppose prevent enlargement. Again, could be wrong, and probably am, but isn't the contribution of a secondary clot a decently significant contributor to mortality in heart attacks? When you have one clot thrown free in the arterial system, you're more than likely to form another (I'm thinking ruptured plaque here). So. Been demonstrated if I recall to have some positive effect. But aren't the real benefits of aspirin found in daily administration and lowering the frequency/size of clots formed. Bha. It's been years since I've read up on this stuff. I can't even find my notes. Like all commercials it's dramatized, scary and loaded with impending doom and black and white statements. I hate them all. Granted, they're also trying to sell to the big chunk of the population that thinks lungs are like big hollow empty balloons, and that your colon builds up thick layers of 'toxins' that have to be purged. Edit: Thought so.