Features September 2018 Issue

Alternative Anticoagulants Gaining in Popularity

Doctors and patients alike prefer them to warfarin for stroke prevention.

If you develop atrial fibrillation (AFib) not associated with a valve problem, there’s a good chance your doctor will prescribe a direct oral anticoagulant (DOAC) instead of warfarin (Coumadin). DOACs are gaining momentum with physicians and patients alike, because they are as effective as warfarin, but easier to use.

“DOACs are performing very well. We are not seeing strokes in patients who take them. We also believe the studies showing they have a lower risk of bleeding than warfarin, because we are experiencing this in our practice,” says Cleveland Clinic electrophysiologist Daniel Cantillon, MD.

Patients with nonvalvular AFib are at increased risk of stroke when blood pools in their heart and forms a clot that can be ejected into the bloodstream. Anticoagulants prevent these clots from forming.

Although DOACs are not approved for AFib caused by valve damage, they are used with increasing frequency in patients with rheumatic heart disease or mitral stenosis, as well.

Warfarin Woes

The first DOAC was approved for stroke prevention in AFib in October 2010. Until that time, the only option was warfarin. Although this old standby is highly effective, its dose must be raised gradually, and patients must undergo regular testing to ensure they maintain enough anticoagulant to prevent clots without incurring unwanted bleeding. They must also eliminate a long list of vitamin K-containing vegetables and fruits from their diet.

DOACs don’t have these restrictions. “Patients find it liberating. They don’t have to be monitored or be fickle with their diet,” says Dr. Cantillon.

The Reversibility (Non)issue

BloodVessel

© Thomas-Soellner | Getty Images

The newer drugs are as effective as warfarin, but easier for patients to use.

The anticoagulant effect of warfarin can be reversed with vitamin K to prevent catastrophic bleeding in patients undergoing major surgery or involved in a traumatic accident. Understandably, many physicians were hesitant to prescribe DOACs until reversal agents were developed. Now that the three major DOACs can be reversed, it appears the need might have been overstated.

“It is remarkable how rarely reversal agents for DOACs are needed. I have been working with these drugs as far back as 2010, and I’ve never had to administer a reversal agent,” says Dr. Cantillon.

When Warfarin May Be Preferred

Despite the excitement over DOACs, warfarin remains the first choice for certain patients. These include those with significantly impaired kidney function.

But there’s a potentially larger group who could benefit from DOACs, but are given warfarin instead: patients who can’t be trusted to take their medication as prescribed.

“Warfarin is a ‘trust but verify’ drug. The level of anticoagulation can be measured with a finger stick. Anticoagulation with DOACs can’t be assessed, so if a patient needs an ablation or cardioversion, we must trust they haven’t missed a dose in 21 days,” says Dr. Cantillon.

The bigger question is why someone at high risk for stroke would fail to take a medication designed to prevent it.

“It’s a mystery, but if you don’t take your anticoagulant, you won’t get the protection,” he says.

How the Need for Anticoagulation Is Determined

In a patient with AFib, the risks of stroke and unwanted bleeding are weighed against the benefits of anticoagulation. The CHADs-VASc and HASBLED scoring systems are used for this purpose. Patients with a high risk of stroke and low risk of bleeding are placed on anticoagulant therapy.

Patients with a high risk of stroke and high risk of bleeding may be advised to have surgery instead. In these patients, a small appendage in the heart where 90 percent of blood clots form is walled off in a procedure called left atrial appendage occlusion.

How the Need for Anticoagulation Is Determined

In a patient with AFib, the risks of stroke and unwanted bleeding are weighed against the benefits of anticoagulation. The CHADs-VASc and HASBLED scoring systems are used for this purpose. Patients with a high risk of stroke and low risk of bleeding are placed on anticoagulant therapy.

Patients with a high risk of stroke and high risk of bleeding may be advised to have surgery instead. In these patients, a small appendage in the heart where 90 percent of blood clots form is walled off in a procedure called left atrial appendage occlusion.

Meet the DOACs: Four DOACs have been approved by the U.S. Food and Drug Administration (FDA) for the prevention of stroke in nonvalvular AFib:
- apixaban/Eliquis®
- rivaroxaban/Xarelto®
- dabigatran/Pradaxa®
- edoxaban (Savaysa)™

In clinical trials, each drug was compared with warfarin. No DOAC has been studied against another. To determine which DOAC to use, physicians must compare how each fared against warfarin.

“It’s like judging two teams that haven’t competed against each other, but have a mutual opponent,” says Dr. Cantillon. “Who knows what would happen if they would play head to head?”

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