Efficacy and safety of dofetilide in the prevention of symptomatic episodes of paroxysmal supraventricular tachycardia: A 6-month double-blind comparison with propafenone and placebo

Background Existing drug therapies For paroxysmal supraventricular tachycar dia (PSVT) have potentially serious adverse effects. Dofetilide, a pure cla ss III antiarrhythmic agent, may offer an effective and safe alternative Fo r treating PSVT. This study compared the efficacy and safety of dofetilide with that of propafenone and placebo in the prevention of PSVT. Methods This multicenter, randomized, placebo-controlled, parallel-group st udy compared the effectiveness of oral dofetilide 500 mug given twice daily with that of propafenone 150 mg given 3 times a day and placebo in prevent ing the recurrence of PSVT in 122 symptomatic patients. Episodes of PSVT we re documented by symptom diaries and Hertcard (Hertford Medical, Hertfordsh ire, UK) event recorders. Results After 6 months of treatment, patients taking dofetilide, propafenon e, and placebo had a 50%, 54%, and 6% probability, respectively, of remaini ng free of episodes of PSVT (P < .001 for both dofetilide and propafenone v s placebo). Both dofetilide and propafenone also decreased the frequency of episodes of PSVT; the median numbers of episodes in the dofetilide- and pr opafenone-treated groups were 1 and 0.5, respectively, compared with 5 in t he placebo-treated group. Dofetilide was well tolerated; no proarrhythmia o ccurred. Three patients taking propafenone had serious treatment-related ad verse effects that required drug discontinuation. Conclusions Dofetilide and propafenone were equally effective in preventing the recurrence of or decreasing the frequency of PSVT.