HEALTH MATTERS: Comparing medicinal blood thinners
Q. I am on a blood thinner after I developed a clot in my leg after a long flight. I understand that there are several newer blood thinners that are easier to take than the medicine I’m on (Warfarin). Should I switch?
A. It depends.
On the one hand, we have decades of experience with Warfarin. On the other hand, the newer agents are easier to take, more convenient and at least as safe as Warfarin (brand name Coumadin).
Warfarin thins the blood and makes it more difficult to clot by interacting with several of the proteins in the blood that promote clotting. The dose is adjusted by a blood test called the prothrombin time (or PT), which measures how thin the blood is and is expressed as a multiple of normal, called the INR (for international normalized ratio). We usually aim for a value of 2 to 3 for patients like you.
As you know, you need to get your PT checked periodically, so the dose of Warfarin can be adjusted appropriately. The newer agents work on different proteins in the blood than warfarin, and they do not require PT tests to adjust the dose, which is fixed. So, the newer agents certainly are easier to take. There are two big “buts,” however. All three of the newer agents are much more expensive than Warfarin, and all three can’t be reversed in the case of bleeding, as we can with Warfarin. So, if you can afford the newer medicines and you are not at increased risk of bleeding, one of them might be a good choice for you.
By the way, of the three new agents, only rivaroxaban (brand name Xarelto) is approved in this country for treatment of leg clots such as you had; the other two (dabigatran, also called Pradaxa, and apixaban, also called Eliquis) are not. And none of the new agents should be used instead of Warfarin for patients with mechanical heart valves.
Q. Before I had a stent inserted, the doctor warned me that I might suffer kidney damage from the procedure. How is that?
A. The risk of kidney damage is unrelated to the stent itself; rather, the main risk comes from the dye or contrast material that we inject into the artery to see it on X-ray, so the stent can be properly positioned at the site of the narrowed segment in the artery. The dye material is carried by the bloodstream to the kidneys, where it can damage them, particularly in patients who also have diabetes.
When it occurs, the kidney damage usually is mild, transient and temporary, but in some cases it can be severe and permanent. Rarely, would the dye damage the kidneys enough to require that the patient undergo dialysis. Newer dye material that is used now is less likely to cause permanent problems than in the past. One of the best protective measures is to make sure that the patient is well-hydrated, so we typically give plenty of intravenous and oral fluids to reduce the risk of kidney problems.
Wynne is vice president for health affairs at the University of North Dakota, dean of the School of Medicine and Health Sciences, and a professor of medicine. He is a cardiologist by training.
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