AF, SVT: propafenone reduced symptomatic arrhythmias

Clinical bottom line (level 2b)

Patients with paroxysmal supraventricular tachycardia or atrial fibrillation who took 600 mg propafenone daily compared with placebo were less likely to have symptomatic arrhythmias (NNT = 3 at 3 months) , without clearly having intolerable adverse effects.
Patients who took 900 mg propafenone daily compared with placebo were less likely to have symptomatic arrhythmias (NNT = 2 at 3 months) , but were more likely to have intolerable adverse effects (NNH = 4 at 3 months) .

UK Propafenone PSVT Study Group : Circulation 1995; 92: 2550-2557

Expires November 2004

The study

Double-blinded ?concealed randomised cross-over trial without intention-to-treat
Setting: acute hospital, UK

100 patients (aged 20 to 78; mean ~60, 54% female) with recurrent attacks of paroxysmal supraventricular tachycardias (diagnosed on 12-lead ECG as AF, or regular narrow-complex tachycardias)

Excluded if

severe COPD

myasthenia gravis

women who were pregnant, lactating or of child-bearing potential not taking adequate contraception

sinus node dysfunction; second or high-degree AV conduction disturbance, bifascicular block; complete bundle-branch block; or distal block

bradycardia < 40 beats/minute or pauses > 4 seconds

prior pacemaker insertion

on antiarrhythmic medication including digoxin if withdrawal was not clinically possible; or on amiodarone within previous 3 months

evidence of haemodynamic collapse, severe left ventricular dysfunction (ejection fraction < 25%) or uncontrolled heart failure

myocardial infarction or unstable angina within previous 3 months

clinically significant hepatic, renal or other disease

uncorrectable electrolyte imbalance

aged < 16, > 80

Note:

Patients had medication withdrawn and were only randomised after 2 further symptomatic episodes documented on ECG had occurred.

Events occurring during the first half-week at 600mg/day and first full week at 900mg/day were not included in the analyses (as 'steady state' alone was studied).

Control Group: (n = 100, 75 analysed): placebo
Experimental Group: (n = 100, 75 analysed): propafenone initially 300 mg once a day, increased after one week to 300 mg twice daily
Experimental Group: (n = 100, 59 analysed): propafenone inially 450 mg a day increased to 300 mg three times a day after one week

75% followed for 3 months

The evidence

propafenone 600 mg v. placebo

Outcome	Time to outcome	CER	EER	RRR (95% CI)	ARR (95% CI)	NNT (95% CI)
symptomatic arrhythmia	3 months	53 (70.7%)	27 (36.0%)	49% (29% to 64%)	34.7% (19.7% to 49.6%)	3 (2 to 5)
intolerable adverse effect	3 months	3 (4.00%)	2 (2.67%)	33% (-290% to 89%)	1.33% (-4.41% to 7.07%)	75 (NNT = 23 to infinity; NNH = 14 to infinity)

propafenone 900 mg v. placebo

Outcome	Time to outcome	CER	EER	RRR (95% CI)	ARR (95% CI)	NNT (95% CI)
symptomatic arrhythmia	3 months	37 (62.7%)	4 (6.78%)	89% (72% to 96%)	55.9% (42.0% to 69.8%)	2 (1 to 2)
intolerable adverse events	3 months	1 (1.69%)	17 (28.8%)	-1600% (-12000% to -130%)	-27.1% (-39.1% to -15.1%)	-4 (-7 to -3)

Comments

Patients were enrolled in the low-dose followed by the high-dose phase of the study. Follow-up was poor making these results less certain.

Citation

UK Propafenone PSVT Study Group , : A randomized placebo-controlled trial of propafenone in the prophylaxis of paroxysmal supraventricular tachycardia and paroxysmal atrial fibrillation. Circulation 1995; 92: 2550-2557

Contributor: Chris Ball and Bob Phillips, November 1999
Reviewer:

_{Clinical Question.}

_Patient	_{paroxsymal atrial fibrillation or supraventricular tachycardia}
_{Intervention or Exposure}	_propafenone
_Comparison	_placebo
_Outcome	_{arrhythmias, adverse effects}