Syncope: cardiovascular causes accounted for a quarter

Clinical bottom line (level 2c)

  1. Common causes of syncope were cardiac arrhythmias, situational syncope and orthostatic hypotension.
  2. One in seven patients with syncope were dead within the next 6 months.
Kapoor et al: New England Journal of Medicine 1983; 309 (4): 197-204
Expires January 2004

The study

Outcome study with objective outcomes, not adjusted for confounding factors, not validated in an independent set of patients.

Setting: university hospital, USA

204 patients (aged 14 to 90; mean 56, 58% female) with syncope

Excluded if
  • required pharmacological or electrical cardioversion at initial presentation
  • tonic-clonic movements, post-ictal state or aura


    • All patients had a standardised history and physical examination; base-line laboratory tests (complete blood count, electrolytes, urine, creatinine, blood glucose, urinalysis), 12-lead ECG and prolonged monitoring; and a definitive evaluation of any features suggestive of a cause of syncope.

    97% followed for 6 months
    Outcomes studied:
  • death
  • cardiovascular cause
  • ventricular tachycardia
  • sick-sinus syndrome sinus pauses of more than 2 seconds, or atrial fibrillation with a slow ventricular response
  • bradycardia, 2nd or 3rd degree heart block
  • supraventricular tachycardia
  • non-cardiovascular cause
  • situational syncope from coughing, micturition, or defecation)
  • orthostatic hypotension decrease in systolic blood pressure > 25 mmHg with dizziness or syncope
  • vasodepressor syncope from fever, severe pain, instrumentation
  • drug-induced syncope evidence of anaphylaxis or related to drug overdose
  • transient ischaemic attacks
  • seizure disorder witnessed episode of tonic-clonic movements or a post-ictal state (confirmed on EEG)

    • The evidence

    outcome time to outcome number of patients/total number %
    (95% CI)
    death 6 months 28/204 14%
    (9.0% to 18%)
    cardiovascular cause 6 months 53/204 26%
    (20% to 32%)
    ventricular tachycardia 6 months 20/204 9.8%
    (5.7% to 14%)
    sick-sinus syndrome 6 months 10/204 4.9%
    (1.9% to 7.9%)
    bradycardia, 2nd or 3rd degree heart block 6 months 7/204 3.4%
    (0.9% to 5.9%)
    supraventricular tachycardia 6 months 3/204 1.5%
    (0.0% to 3.1%)
    non-cardiovascular cause 6 months 54/204 26%
    (20% to 33%)
    situational syncope 6 months 15/204 7.4%
    (3.8% to 11%)
    orthostatic hypotension 6 months 14/204 6.9%
    (3.4% to 10%)
    vasodepressor syncope 6 months 9/204 4.4%
    (1.6% to 7.2%)
    drug-induced syncope 6 months 6/204 2.9%
    (0.6% to 5.3%)
    transient ischaemic attacks 6 months 3/204 1.5%
    (0.0% to 3.1%)
    seizure disorder 6 months 3/204 1.5%
    (0.0% to 3.1%)

    Comments

    1. One patient had carotid-sinus syncope, one had a dissecting aortic aneurysm and one a pulmonary embolism.
    2. 49% of diagnoses were made on history and physical examination alone; ECG added another 11% of diagnoses, and ECG monitoring another 27%.

    Citation

    1. Kapoor WN, Karpf M, Wieand S, et al: a prospective evaluation and follow-up of patients with syncope. New England Journal of Medicine 1983; 309 (4): 197-204
    Contributor: Chris Ball and Clare Wotton, November 1999
    Reviewer:

    Clinical Question.
    Patient syncope
    Intervention or Exposure prevalence
    Outcome cause, death