Moreover all the anti-arrhythmic agents that are used in treatment of AF were potentially pro-arrhythmic especially in patients with coronary artery disease and structurally abnormal heart .
Although atrial fibrillation ( AF ) is the most common sustained arrhythmia seen during daily cardiovascular physician practice , its management remained a challenge for cardiology physician as there was no single anti-arrhythmic agents proved to be effective in converting atrial fibrillation and kept its effectiveness in maintaining sinus rhythm over long term .
Some of these drugs also have serious non cardiac side effects that limit its long term use in the management of atrial fibrillation .
Several new and investigational anti-arrhythmic agents are emerging but data supporting their effectiveness and safety are still limited .
Ventricular rate control in chronic atrial fibrillation during daily activity and programmed exercise: a crossover open-label study of five drug regimens.
OBJECTIVES We compared the effects of five pharmacologic regimens on the circadian rhythm and exercise-induced changes of ventricular rate ( VR ) in patients with chronic atrial fibrillation ( CAF ) . BACKGROUND Systematic comparison of st and ardized drug regimens on 24 h VR control in CAF have not been reported . METHODS In 12 patients ( 11 male , 69+/-6 yr ) with CAF , the effects on VR by 5 st and ardized daily regimens : 1 ) 0.25 mg digoxin , 2 ) 240 mg diltiazem-CD , 3 ) 50 mg atenolol , 4 ) 0.25 mg digoxin + 240 mg diltiazem-CD , and 5 ) 0.25 mg digoxin + 50 mg atenolol ; were studied after 2 week treatment assigned in r and om order . The VR data were analyzed by ANOVA with repeated measures . The circadian phase differences were evaluated by cosinor analysis . RESULTS The 24-h mean ( + /-SD ) values of VR ( bpm ) were - digoxin : 78.9 + /- 16.3 , diltiazem : 80.0+/-15.5 , atenolol : 75.9+/-11.7 , digoxin + diltiazem : 67.3+/-14.1 and digoxin + atenolol : 65.0+/-9.4 . Circadian patterns were significant in each treatment group ( p < 0.001 ) . The VR on  digoxin + atenolol  was significantly lower than that on digoxin ( p < 0.0001 ) , diltiazem ( p < 0.0002 ) and atenolol ( p < 0.001 ) . The time of peak VR on Holter was significantly delayed with regimens 3 and 5 which included atenolol ( p < 0.03 ) . During exercise , digoxin and digoxin + atenolol treatments result ed in the highest and lowest mean VR respectively . The exercise Time-VR plots of all groups were nearly parallel ( p = ns ) . The exercise duration was similar in all treatment groups ( p = ns ) . CONCLUSIONS This study indicates that digoxin and diltiazem , as single agents at the doses tested , are least effective for controlling ventricular rate in atrial fibrillation during daily activity . Digoxin + atenolol produced the most effective rate control reflecting a synergistic effect on the AV node . The data provides a basis for testing the effects of  chronic suppression of diurnal fluctuations of VR  on left atrial and ventricular function in CAF
Moreover all the anti-arrhythmic agents that are used in treatment of AF were potentially pro-arrhythmic especially in patients with coronary artery disease and structurally abnormal heart .
Although atrial fibrillation ( AF ) is the most common sustained arrhythmia seen during daily cardiovascular physician practice , its management remained a challenge for cardiology physician as there was no single anti-arrhythmic agents proved to be effective in converting atrial fibrillation and kept its effectiveness in maintaining sinus rhythm over long term .
Some of these drugs also have serious non cardiac side effects that limit its long term use in the management of atrial fibrillation .
Several new and investigational anti-arrhythmic agents are emerging but data supporting their effectiveness and safety are still limited .