Tachycardia: flecainide had a dose-response effect.

Clinical bottom line (level 1b)

  1. Patients with supraventricular tachycardia who were given flecainide, 150 mg, were more likely to have no arrhythmic attacks than those given placebo (NNT = 2 at 5 months) .
  2. Patients given flecainide, 100 mg, were more likely to have no arrhythmic attacks than those given placebo (NNT = 3 at 5 months) .
  3. Patients given flecainide, 25 or 50 mg, had no clear difference in arrhythmic attacks.
Pritchett et al: Journal of American College of Cardiology 1991; 17: 297-303
Expires October 2004

The study

Double-blinded concealed randomised cross-over trial without intention-to-treat
Setting: multicentre, USA

28 patients (aged mean 45 years, 61% male) paroxysmal supraventricular tachycardia

Excluded if
  • <18 years old
  • non-compliance with protocol or unanalysable data
  • tachycardia produced angina, neurological symptoms or heart failure
  • anti-tachycardia pacemaker
  • pregnant or lactating


    • Control Group: (n = 28, 14 analysed): placebo
    Experimental Group: (n = 28, 14 analysed): flecainide in doses of 25, 50, 100 and 150 mg twice daily
    Each treatment period lasted a maximum of 31 days. Placebo treatment was inserted randomly as the first treatment or between two of the flecainide treatments.
    100% followed for 5 months

    The evidence

    Outcome Time to outcome CEREERRRR
    (95% CI)    		ARR
    (95% CI)    		NNT
    (95% CI)
    no episodes of supraventricular tachycardia- 25 mg flecainide 31 days 4
    (28.6%)    		 5
    (35.7%)    		 -25.0%
    (-270% to 58.0%)    		 -7.14%
    (-41.6% to 27.4%)    		 14
    (NNT = 2 to infinity;
    NNH = 4 to infinity)
    no attacks-50 mg flecainide 31 days 4
    (28.6%)    		 8
    (57.1%)    		 -100%
    (-414% to 22.0%)    		 -28.6%
    (-63.7% to 6.53%)    		 4
    (NNT = 2 to infinity;
    NNH = 15 to infinity)
    no attacks-100 mg flecainide 31 days 4
    (28.6%)    		 9
    (64.3%)    		 -125%
    (-462% to 10.0%)    		 -35.7%
    (-70.2% to -1.22%)    		 3
    (1 to 82)
    no attacks-150 mg flecainide 31 days 4
    (28.6%)    		 12
    (85.7%)    		 -200%
    (-606% to -28.0%)    		 -57.1%
    (-87.1% to -27.2%)    		 2
    (1 to 4)

    Comments

    1. Noncardiac adverse reactions (headache, dizziness, nausea, dyspnoea, flushing and fatigue) did not differ a great deal between any of the doses and placebo; placebo, 7; 25 mg flecainide, 6; 50 mg, 7; 100 mg, 6; 150 mg, 10.

    Citation

    1. Pritchett ELC, Datorre SD, Platt ML, et al: Flecainide acetate treatment of paroxysmal supraventricular tachycardia and paroxysmal atrial fibrillation: Dose-response studies. Journal of American College of Cardiology 1991; 17: 297-303
    Contributor: Clare Wotton and Bob Phillips, October 1999
    Reviewer:

    Clinical Question.
    Patient paroxysmal supraventricular tachycardia
    Intervention or Exposure flecainide
    Comparison placebo
    Outcome efficacy