Atrial fibrillation, atrial flutter: bradyarrhythmias were common on starting antiarrhythmic medication

Clinical bottom line (level 4)

  1. One in seven patients with atrial fibrillation or flutter starting anti-arrhythmic medication had a cardiac adverse event - half with bradyarrhythmias.
  2. Symptomatic bradyarrhythmia and ventricular arrhythmias were rare. Very few patients suffered cardiac emboli.
  3. Patients with a previous myocardial infarction were more likely to suffer an adverse effect.
Maisel et al: Annals of Internal Medicine 1997; 127 (4): 281-284
Expires December 2003

The study

Case series with ?objective ?blinded outcomes, adjusted for confounding factors, not validated in an independent set of patients.

Setting: university hospital, USA

417 patients (aged mean 64, 59% male) with atrial fibrillation or flutter (confirmed on ECG - duration for a mean of 12 months) underwent initiation of antiarrhythmic drug therapy for conversion to sinus rhythm or maintenance of sinus rhythm following cardioversion. Patients underwent a total of 597 drug trials during a total of 550 hospitalisations.

Excluded if
  • aged < 18
  • acute illness, such as acute myocardial infarction
  • cardiac surgery within 30 days of admission
  • previous heart transplantation
  • amiodarone treatment within 1 year of admission




    • Multivariate logistic regression was used to adjust for confounding factors.

    ?100% followed for 3 days
    Outcomes studied:
  • cardiac adverse event ventricular arrhythmias, bradyarrhythmias, prolonged QT interval, conduction abnormalities, congestive heart failure, rapid ventricular rate, or hypotension requiring medical intervention, or discontinuation or reduction in dose of medicine; or a cerebrovascular event
  • bradyarrhythmia
  • symptomatic bradyarrhythmia
  • ventricular arrhythmia
  • torsade de pointes
  • cerebrovascular emboli confirmed on CT scan
  • any adverse effect

    • The evidence

    outcome time to outcome number of patients/total number %
    (95% CI)    		 NNF
    (95% CI)
    cardiac adverse event 3 days 80/597 13%
    (11% to 16%)    		 7
    (6 to 9)
    bradyarrhythmia 3 days 47/597 7.9%
    (5.7% to 10%)    		 13
    (10 to 18)
    symptomatic bradyarrhythmia 3 days 25/597 4.2%
    (% to %)    		 24
    (17 to 39)
    ventricular arrhythmia 3 days 8/597 1.3%
    (0.4% to 2.3%)    		 75
    (44 to 240)
    torsade de pointes 3 days 1/597 0.2%
    (0.0% to 0.5%)    		 600
    (200 to infinity)
    cerebrovascular emboli 3 days 2/597 0.3%
    (0.0% to 0.8%)    		 300
    (130 to infinity)
    any adverse effect 3 days 163/597 27.3%
    (% to %)    		 4
    (3 to 4)

    prognostic factor for
    any adverse effect     		time to outcome control rate (%) adjusted OR
    (95% CI)
    patient had previous myocardial infarction ? 1.90
    (1.05 to 3.43)

    Citation

    1. Maisel WH, Kuntz KM, Reimold SC, et al: Risk of initiating antiarrhythmic drug therapy for atrial fibrillation in patients admitted to a university hospital. Annals of Internal Medicine 1997; 127 (4): 281-284
    Contributor: Chris Ball and Clare Wotton, December 1999
    Reviewer:

    Clinical Question.
    Patient atrial fibrillation
    Intervention or Exposure anti-arrhythmic medication
    Outcome adverse effects