The second focused update endorses dabigatran (Pradaxa), a new drug that like warfarin represents a first-line choice to prevent thromboembolism in AF.2 The FDA approved dabigatran in October 2010. It is “the first new oral anticoagulant to become available for clinical use in more than 50 years,” according to FDA officials.

In a large randomized trial rates of stroke and systemic embolism were comparable in AF patients treated with dabigatran and warfarin, and the new drug carried a 20% lower risk of major bleeding episodes.


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Dabigatran’s principal advantage is ease of use. The drug requires neither dietary restrictions nor regular INR testing and is given in a fixed dose. Because it is metabolized independently of liver enzymes, drug-drug interactions are unlikely.

On the other hand, GI side effects are more common with dabigatran than with warfarin, and the additional expense of the newer drug may be a deterrent for some patients.

Wann observed that dabigatran was approved as an anticoagulant for AF only and is not indicated for patients who have prosthetic heart valves, valvular disease or other conditions that require anticoagulation.

Although the update committee did not address the use of the aspirin-clopidigrel combination in the context of dabigatran, it would seem logical to consider the combination only for patients who cannot or will not take either of the two anticoagulants, according to Wann.

A new anti-arrhythmic drug

Patients in whom paroxysmal or persistent AF is highly symptomatic or leads to hospitalization may require anti-arrhythmic pharmacotherapy to maintain sinus rhythm. This will generally mean referral, or at least consultation with a cardiologist.

The ACCF/AHA update adds dronedarone (Mulutaq) as reasonable option for rhythm control.

Dronedarone, which chemically resembles the anti-arrhythmic amiodarone (Cordarone), is safer but less effective than the older drug. Safety, in fact, is its chief advantage: dronedarone does not pose the risk for serious adverse events, thyroid and pulmonary toxicity in particular — the chief drawbacks with amiodarone.

On the other hand, a head-to-head trial of the two drugs found dronedarone significantly less effective than amiodarone in reducing recurrences among patients with persistent AF.

Because of its superior safety, clinicians may consider dronedarone early in treating most patients with persistent or recurrent paroxysmal AF, whereas amiodarone is generally recommended for use after other agents have failed.

For patients with heart failure, the more powerful amiodarone remains the drug of choice and dronedarone is not recommended.

Catheter ablation

Additional evidence of the efficacy of catheter-based ablation therapy — radiofrequency destruction of small areas of heart tissue responsible for rhythm disturbance — has strengthened recommendations for its use in patients with persistent AF who have failed to improve with one or more antiarrhythmic drugs.

The ACCF/AHA update also recommends that catheter ablation be considered for a wider group of patients, including those with symptomatic paroxysmal AF.

“Catheter ablation is a great procedure in the right hands for the right patients. It is not for everyone,” Wann said. The authors of the ACCF/AHA update noted that in the studies cited, “all ablation procedures were performed by highly experienced operators in high-volume centers.”

They also pointed out that while most patients appear to remain free of recurrent AF for at least a year after catheter ablation, data on long-term efficacy are lacking.

Similarly, there is no clear evidence on when — or indeed whether — it is safe to discontinue anticoagulation after successful catheter ablation.

Mr. Sherman is a freelance medical writer in New York City.

References

1. Wann LS, Curtis AB, January CT et al. 2011 Circulation. 2011;123:104-123.

2. Wann LS, Curtis AB, Ellenbogen KA et al. Circulation. 2011;123:1144-1150.

All electronic documents accessed July 15, 2011.