THE INCIDENCE OF ASYMPTOMATIC PAROXYSMAL ATRIAL-FIBRILLATION IN PATIENTS TREATED WITH PROPRANOLOL OR PROPAFENONE

Anti-arrhythmic therapy for paroxysmal atrial fibrillation leads to co mplete symptomatic relief in a number of patients, The elimination of symptoms may be associated either with a complete elimination of arrhy thmia or with a conversion of symptomatic atrial fibrillation into asy mptomatic episodes of arrhythmia. The aim of the study was to evaluate the occurrence of asymptomatic paroxysmal atrial fibrillation in 52 p atients treated with propafenone (35 drug trials) or propranolol (34 d rug trials) by means of ambulatory ECG Holter monitoring, Propafenone was clinically effective (complete relief of symptoms) in 26 (74%) pat ients. However, in 7 cases (27%) asymptomatic episodes of arrhythmia w ere still recorded when awake. In patients treated with propranolol cl inical symptoms were absent in 18 (53%). However, in 4 (22%) patients attacks of paroxysmal atrial fibrillation were present. The mechanism of drug-induced conversion of symptomatic episodes of atrial fibrillat ion into asymptomatic spells of arrhythmia was a marked shortening in duration of episodes in 7 patients (from 2215 +/- 3843 s to 16 +/- 10 s, N.S,) or by a significant slowing of ventricular response during at rial fibrillation in 4 patients (from 125 +/- 27 to 84 +/- 8 beats/min , P = 0.05). In conclusion, in a significant proportion of patients wi th symptomatic paroxysmal atrial fibrillation asymptomatic episodes of arrhythmia may occur while on anti-arrhythmic drug therapy. Some of t hese patients, particularly those with other risk factors for stroke s uch as advanced age or the presence of organic heart disease, may requ ire anti-coagulant therapy or change in anti-arrhythmic treatment, and can be selected on the basis of ambulatory ECG monitoring.