Cardiology Xagena

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Patients less than 65 years with atrial fibrillation and without structural heart disease: high rate of discontinuation of antiarrhythmic therapy

Little is known in clinical practice about antiarrhythmic drugs ( AADs ) use in patients with atrial fibrillation ( particularly younger ones ) who do not have structural heart disease.

Using the MarketScan database, researchers have identified patients less than 65 years without known coronary artery disease or heart failure who had an antiarrhythmic drug prescription claim ( class Ic drug, Amiodarone [ Cordarone ], Sotalol [ Sotalex ], or Dronedarone [ Multaq ] ) after their first atrial fibrillation encounter.

A multinomial logistic regression model was created to assess factors associated with using each available antiarrhythmic drug compared with using class Ic drugs before and after Dronedarone was marketed in the United States.

Additionally, researchers used the Kaplan-Meier method to determine the rates of change in antiarrhythmic drugs use and discontinuation during the year after antiarrhythmic drug initiation.

Of 8,562 patients with atrial fibrillation, 35% received class Ic drugs, 34% Amiodarone, 24% Sotalol, and 7% Dronedarone. The median patient age was 56 ( interquartile range 49 to 61 ), and 34% were women.

Both before and after Dronedarone was marketed, there was a statistically significant lower likelihood of class Ic drug use versus other antiarrhythmic drugs use with increasing age, inpatient index atrial fibrillation encounter, and previous or concomitant anticoagulation therapy.

During the 1 year after antiarrhythmic drug initiation, the antiarrhythmic drug change rate was 14% for class Ic drugs, 8% for Amiodarone, 17% for Sotalol, and 18% for Dronedarone ( p less than 0.001 ); the discontinuation rate was 40% for class Ic drugs, 52% for Amiodarone, 40% for Sotalol, and 69% for Dronedarone ( p less than 0.001 ).

In conclusion, the researchers found extensive use of Amiodarone that may be inconsistent with guideline recommendations and unexpectedly high rates of discontinuation of antiarrhythmic therapy. ( Xagena )

Allen LaPointe NM et al, Am J Cardiol 2014; Epub ahead of print