Efficacy of Antiarrhythmic Drugs for Atrial Fibrillation Is Differently Dependent on Left Atrial Remodeling

Objectives: The association between the efficacy of AADs and LA size in AF management remains unclear. Methods: 383 patients with symptomatic paroxysmal or persistent AF (PeAF) (282 male, 59±12 years), who were treated with class Ic drug (n=343; flecainide, n=336 or propafenone, n=54) or amiodarone (n = 155), were analyzed. Results: 165 (48%) did not respond to class Ic drug and 92(59%) did not to amiodarone. Class Ic drug failure group had more PeAF (39% vs 14%, p<0.01), larger LA size(42±7 vs 40±6, p<0.01) and more LA AP diameter (LAd)>41mm (61% vs 44%, p<0.01). There was no statistical difference in other clinical and echocardiographic parameters (all p>0.05). Amiodarone failure group had more PeAF (49% vs 29%, p<0.01) but was not related to LA size (p>0.05). PeAF (OR 4.5, 95% CI:2.588~7.823, p<0.01) and LAd>41mm (OR 1.7, 95% CI:1.057~2.703, p=0.03) were independent predictors of class Ic drug failure, whereas only PeAF was an independent predictor of amiodarone failure. Class Ic drug failure rates in paroxysmal AF with LAd<41mm, paroxysmal AF with LAd>41mm, PeAF with LAd<41mm and PeAF with LAd>41mm were 33%, 45%, 70% and 77%. respectively (p<0.01). Conclusions: The efficacy of class Ic AADs was dependent on LA size and AF type synergistically, whereas the efficacy of amiodarone was not associated with LA size.