Propafenone is a new class IC antiarrhythmic drug that has been found to be effective in both supraventricular and ventricular tachyarrhythmias. We studied the electrophysiologic and long-term effects of oral propafenone in the patients with paroxysmal supraventricular tachycardia(PSVT).

The electrophysiologic study was done in 15 patients with PSVT to assess the short-term efficacy of propafenone 450mg daily. For 10 patients with short-term efficacy, follow up study was done to assess the long-term efficacy of propafenone 450mg daily.

The electrophysiologic mechanisms of PSVT were AV nodal reentry in 6 patients and AV reentry in 9 patients. During the electrophysiologic study, propafenone prolonged AH, HV and PR intervals significantly(p<0.05), but did not change the corrected SNRT, SACT, and the ERP of atrium, ventricle, AV node and accessory pathway(AP) significantly. The anterograde and retrograde 1:1 conduction capacity of AV node and AP seemed to decrease. Complete block of anterograde conduction over the AP was noted in 2 of 3 patients with manifest WPW syndrome and complete block of retrograde conduction was noted over the AV node in 1 patient with AV nodal reentry and over the AP in 1 patient with AV reentry. Propafenone was effective in 3 of 6 patients with AVNRT and 7 of 9 patients with AVRT. During long term administration for 3 to 11 months in 10 patients with short-term efficacy of propafenone, 7 patients did not report any episode of symptomatic tachycardia and 3 patients reported less frequent palpitation. There were no side effects during short-and long-term follow up except 2 patients with mild indigestion.

Propafenone seems to be a safe, well tolerated and effective drug for short and long-term therapy of patients with PSVT, especially of orthodromic AV reentry.