Syncope: heart disease increased the risk of dying

Clinical bottom line (level 1b)

  1. 20% of patients with syncope and no cause found on history or physical examination had a cardiac arrhythmia.
  2. Patients with syncope and no cause diagnosed on history and physical examination were more likely to have a cardiac arrhythmia if they had
    • no nausea or vomiting before syncope
    • an abnormal ECG
  3. One in eleven patients were dead within one year.
  4. Patients were more likely to die if they had heart disease
  5. Patients were more likely to have a recurrent episode of syncope if they
    • had 4 or more episodes of syncope in the last year
    • had 2 or more psychiatric diagnoses
    • were aged 45 or less
Oh et al: Archives of Internal Medicine 1999; 159: 375-380
Expires November 2004

The study

Inception cohort study with blinded outcomes, adjusted for confounding factors, not validated in an independent set of patients.

Setting: university hospital, USA

275 patients (aged mean 57, 58% female) with syncope (a sudden transient loss of consciousness with an inability to maintain postural tone) and a cause not found on history and physical examination

Excluded if
  • aged < 18
  • failed to regain consciousness spontaneously
  • requiring pharmacological or electrical cardioversion
  • symptoms compatible with seizure disorder, vertigo, dizziness, coma, shock or other states of altered consciousness



    • Factors studied:
  • complete history and physical examination (particularly cardiac comorbidity, trauma, age, sex), baseline laboratory tests (blood count, electrolytes, urea, creatinine, glucose), 12-lead ECG and prolonged ECG monitoring for at least 24 hours.
  • absence of nausea or vomiting before syncope
  • abnormalities on ECG
  • aged 45 or less
  • 4 or more episodes of syncope in the last year
  • 2 or more psychiatric diagnoses
  • mild heart disease with or without limitation of normal activity
  • severe heart disease with symptoms at less than normal activity or at rest




    • Multivariate regression analysis used to adjust for confounding factors.

    99% followed for 1 year
    Outcomes studied:
  • syncope due to cardiac arrhythmia
  • recurrent syncope
  • death

    • The evidence

    outcome time to outcome number of patients/total number %
    (95% CI)    		 NNF
    (95% CI)
    syncope due to cardiac arrhythmia 1 year 55/275 20%
    (15% to 25%)    		 5
    (4 to 7)
    recurrent syncope 1 year -/- 34%
    (% to %)
    death 1 year 24/275 8.7%
    (5.4% to 12%)    		 11
    (8 to 19)

    prognostic factor for
    syncope due to cardiac arrhythmia     		time to outcome control rate (%) adjusted OR
    (95% CI)    		 NNF+
    (95% CI)
    absence of nausea or vomiting before syncope 12 months 55/275
    (20.0%)     		7.1
    (1.6 to 33.3)     		2
    (1 to 12)
    abnormalities on ECG 12 months 55/275
    (20.0%)     		23.5
    (7.0 to 78.7)     		2
    (1 to 2)

    prognostic factor for
    recurrent syncope     		time to outcome adjusted RR
    (95% CI)    		 NNF+
    (95% CI)
    aged 45 or less 1 year 1.9
    (1.1 to 3.4)     		3
    (1 to 29)
    4 or more episodes of syncope in the last year 1 year 3.8
    (2.1 to 7.0)     		1
    (1 to 3)
    2 or more psychiatric diagnoses 1 year 2.3
    (1.0 to 1.6)     		2
    (5 to infinity)

    prognostic factor for
    death     		time to outcome adjusted RR
    (95% CI)    		 NNF+
    (95% CI)
    mild heart disease 1 year 7.7
    (1.6 to 36.4)     		2
    (1 to 19)
    severe heart disease 1 year 13.5
    (2.6 to 70.5)     		1
    (1 to 7)

    Comments

    1. 45% (222/497) of patients with syncope had a diagnosis made on the basis of history and physical examination alone.
    2. The rate of recurrent syncope was not reported - assumed to be 34% (taken from a previous study in the same institution).

    Citation

    1. Oh JH, Hanusa BH, Kapoor WN: Do symptoms predict cardiac arrhythmias and mortality in patients with syncope?. Archives of Internal Medicine 1999; 159: 375-380
    Contributor: Chris Ball and Clare Wotton, November 1999
    Reviewer:

    Clinical Question.
    Patient syncope with no clear cause on history or physical examination
    Intervention or Exposure clinical features, symptoms
    Outcome recurrent syncope, death, cardiac arrhythmia