But problems occur with too little as well as too much. Bob was the brightest in our class and went on to be a CEO of a Fortune 500 company. But he had a bicuspid aortic valve that needed replacement. At that time only a mechanical valve was possible. After successful surgery he required life long anti-coagulation with Warfarin (Coumadin). Because of frequent travels and time zone changes, he found it very difficult to monitor his INR blood test in order to adjust his dose. Unfortunately the dose was inadequate for a few days and he had a large blood clot on the valve which traveled to his brain causing a massive stroke from which he never recovered.My patients would ask me if I was going to prescribe “rat poison” when they needed a blood thinner, and after saying “yes” we had a long discussion about the pros and cons and need for careful monitoring. Warfarin was isolated at the WARF, the University of Wisconsin Research Foundation and has an interesting history. No doubt its use has saved innumerable lives. But it’s a difficult drug to dose and monitor correctly, has some drug-drug interactions, and is interfered with by Vitamin K containing foods or meds.
The race has been on to find an oral anticoagulant this is safe, effective, and requires no monitoring. There are several now and it’s certainly worth discussing with your physician. Unfortunately the new drugs don’t have a reversing agent if there is an overdose or bleeding episode. Here’s one set of recommendations for the newer drugs – note there are unfortunately more side effects when over the age of 75:
- Patients who have unstable INR on warfarin not due to poor compliance
- Reasonably good renal & hepatic function
- No mechanical valve
- Not pregnant (drugs cross placenta)
- < 75 years old
- No history of lower GI bleeding
So no, we don’t have a “Goldilocks” anticoagulant yet. But the drug companies are getting closer. Warfarin is relatively cheap in the generic form, the others aren’t. So there are lots of tradeoffs as we move into the future.