Considerations for Using Warfarin in NVAF

Gary M. Besinque, PharmD, FCSHP; Jaime E. Murillo, MD; Juvairiya Pulicharam, MD; Ralph J. Riello III, PharmD, BCPS; and Peter Salgo, MD, review practical implications for using warfarin in patients with nonvalvular atrial fibrillation as a strategy for preventing stroke.

Transcript Peter Salgo, MD: What about the problem that you have with warfarin, in terms of drug interactions and dietary interactions? Where do we start with all of this? What drugs can you not give, or should you not give? What do you have to be careful of?

Ralph J. Riello III, PharmD, BCPS: That’s job security for me, as a pharmacist—the patients who are still clinging to their warfarin, such as those characteristic little old ladies who come in during their clinic visits and tell you about their cats and how their grandson just made the honor roll. They’ve been on warfarin for their whole lives. You still have to reinforce that there needs to be consistency with leafy greens and their diets. Many times, our patients get the wrong message— “I can’t eat salad anymore.” It’s an excuse to go back to the meat and potato diet. This is not the case. You can eat whatever you like. If you like those kale smoothies, you can still have those. You just have to be consistent with them. There are antis. I think of them as the drugs that tend to interact the most. The antibiotics and antiarrhythmics tend to wreak havoc on the cytochrome system that warfarin is metabolized through.

Peter Salgo, MD: But, in fact, you can create a structure for these patients, right? Do you warn patients about diets, other drugs, and about visiting Dr. B, who is going to put them on a drug and the patient isn’t going to tell him/her that they’re on warfarin? Is that an issue?

Gary M. Besinque, PharmD, FCSHP: Sure. You definitely have the discussion about the medications that they’re on. If you’re talking about warfarin, those leafy greens are something that have to be kept as smooth as possible over time.

Peter Salgo, MD: So it’s not an excuse to have steak and potatoes with lots of gravy? You can do the leafy greens, but you’ve got to know what you’re doing?

Gary M. Besinque, PharmD, FCSHP: That’s when you have to add the aspirin back.

Peter Salgo, MD: For the other consequences and the statin. What do statins do with warfarin?

Ralph J. Riello III, PharmD, BCPS: Certain ones interact. We think of simvastatin as one that interacts with a large majority of the drugs that we use in the cardiovascular space. You have to be careful when you start it and know to look out for that.

Peter Salgo, MD: OK, you have to be careful. It’s somewhere in Harrison’s. I have read that somewhere.

Ralph J. Riello III, PharmD, BCPS: And you may have to make some changes to the warfarin regimen, down the road.

Peter Salgo, MD: People worry about hypertension—hypertensive patients being put on warfarin. What’s the issue here? Why are they worried? Should they worry?

Ralph J. Riello III, PharmD, BCPS: We know that hypertension is a risk factor for stroke and bleeding events. When patients are on warfarin, we mentioned that they are at higher risk for intracranial hemorrhage. Being hypertensive is certainly a precursor, if not a risk factor for that. These things need to be managed. We know that hypertension is one of the most modifiable risk factors for stroke, itself, so we need to follow the new guidelines and updates. We need to get our patients within guideline range, for their blood pressure, particularly if they have AFIB [atrial fibrillation].

Peter Salgo, MD: But what is this drum beat of hypertension? You can’t anticoagulate somebody whose blood pressure is too high?

Jaime E. Murillo, MD: The key is to keep in mind that hypertension is one of the leading causes of atrial fibrillation because it leads to hypertensive heart disease, structural damage to the atria, and, therefore, predisposition to atrial fibrillation. That is No. 1. No. 2, as you pointed out, is the association between hypertension and stroke. The issue is, “Now you have hypertension. Let’s treat the hypertension.”

Peter Salgo, MD: That’s a novel concept. If you’re hypertensive, don’t stop the warfarin. Treat the hypertension.

Jaime E. Murillo, MD: Treat the hypertension. I can’t tell you how often the rates of atrial fibrillation, when it’s paroxysmal, are clearly correlated with blood pressure control.

Juvairiya Pulicharam, MD: I agree with that. It’s very important to look at the patient, as a whole, and look at all of the comorbidities when you’re making decisions. You can’t just isolate a disease state.

Peter Salgo, MD: You can’t just focus on anticoagulation? You’ve got to look at the whole patient?

Juvairiya Pulicharam, MD: I wish they only came in with 1 disease state, not related with anything else, right?

Peter Salgo, MD: That’s engineering. That’s not medicine.

Juvairiya Pulicharam, MD: Yes.

Peter Salgo, MD: There are a lot of moving parts in the human body. Is there ever a time, pharmacologically, when you back off warfarin because of hypertension? Maybe there’s a drug interaction with the drugs that you need to use for the hypertension. Anything?

Ralph J. Riello III, PharmD, BCPS: To me, frankly, almost none. Maybe I’d do this when a patient shows up with hypertension emergency or urgency, in an emergency department, when we’d want to get that blood pressure under control. But, beyond that, this is a very rare clinical scenario. Hypertension is not something that’s a do or don’t for me, in terms of anticoagulation.

Jaime E. Murillo, MD: I agree.

Peter Salgo, MD: It’s just a question of being careful and doing it right.

Ralph J. Riello III, PharmD, BCPS: Exactly.

Peter Salgo, MD: If somebody comes in with a hypertensive crisis, you treat that. “Don’t worry so much about the warfarin right now. We’ll pick it back up.”

Ralph J. Riello III, PharmD, BCPS: Yes.

Peter Salgo, MD: It seems to me that there are 2 causes of stroke. One is a bleed, and one is an embolus. With AFIB, the embolus is up there and the risk of an embolic stroke, compared to somebody in sinus rhythm, is much higher. So, that’s where we’re going.