Syncope: electrophysiologic studies detected arrhythmias in patients with unexplained syncope.

Clinical bottom line (level 4)

  1. Electrophysiologic studies detected abnormal rhythms in two thirds of patients with unexplained syncope.
  2. Patients who had normal EPS results were as likely to die or have further syncopal episodes as ones that had abnormal studies.
Doherty et al: American Journal of Cardiology 1985; 55: 703-708
Expires October 2004

The study

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

Setting: university hospital, USA

119 patients (aged mean 51 years, 58% male) having electrophysiologic for unexplained syncope (82%) or presyncope (feeling of imminent loss of consciousness without actually doing so)

Excluded if
  • documented bradycardia or tachycardia
  • neurologic cause
  • haemodynamic abnormality (e.g. aortic stenosis)
  • incomplete study




    • Logistic regression performed for risk factors predictive of positive EPS: structural heart disease; previous MI

    71% followed for mean 32 months
    Outcomes studied:
  • any abnormality
  • ventricular tachycardia
  • AF or flutter
  • vasovagal
  • carotid sinus syndrome
  • SVT

    • The evidence

    outcome time to outcome number of patients/total number %
    (95% CI)
    any abnormality mean 32 months 78/119 66%
    (57% to 74%)
    ventricular tachycardia mean 32 months 31/119 26%
    (18% to 34%)
    AF or flutter mean 32 months 17/119 14%
    (8.0% to 21%)
    vasovagal mean 32 months 8/119 6.7%
    (2.2% to 11%)
    carotid sinus syndrome mean 32 months 7/119 5.9%
    (1.7% to 10%)
    SVT mean 32 months 6/119 5.0%
    (1.1% to 9.0%)

    • 11/57 (19%: 95% CI: 9.1 to 30) of patients with positive EPS had further symptoms, and 4/57 (7%: 95% CI: 0.4 to 14) died.
    • 4/28 (14%: 95% CI: 1.3 to 27) of patients with negative EPS had further symptoms, and 1/28 (4%: 95% CI: 0.0 to 10) died.

    Comments

    1. Study too small to detect small differences in outcome between two groups - also poor follow-up.
    2. One explanation for the similarity in outcome between the positive and negative EPS groups is that the arrhythmias detected are not related to the true cause of the syncope.

    Citation

    1. Doherty JU, Pembrook-Rogers D, Grogan EW, et al: Electrophysiologic evaluation and follow-up characteristics of patients with recurrent unexplained syncope and presyncope. American Journal of Cardiology 1985; 55: 703-708
    Contributor: Chris Ball and Clare Wotton, October 2000
    Reviewer:

    Clinical Question.
    Patient unexplained syncope
    Intervention or Exposure electrophysiologic studies
    Outcome detecting abnormal rhythms