Syncope: a standardised work-up found a cause in two-thirds of patients

Clinical bottom line (level 2b)

  1. 1% of patients attending an emergency department had syncope
  2. Common causes of syncope included vasodepressor syncope, orthostatic hypotension and arrhythmias.
  3. A standardised work-up found a cause in two-thirds of patients.
Sarasin et al: Am J Med 2001; 111 : 177-184
Expires May 2004

The study

Setting: emergency department, university hospital, Switzerland

650 patients (aged 18 to 93; mean 60, 52% female) presenting with a chief complaint of syncope (sudden transient loss of consciousness with an inability to maintain postural tone and a spontaneous recovery)

Excluded if
  • aged < 18
  • symptoms clearly compatible with seizure disorders, vertigo, dizziness, coma or shock


Non-independent unblinded reference standard, applied in all patients from a consecutive appropriate spectrum.
Reference standard:
  • by 2 internists and a cardiologist using explict and reproducible criteria. Symptoms associated with the syncopal episode had to be reproducible during a confirmatory diagnostic procedure.
    • vasovagal disorder: presence of premonitory signs and a precipitating event; or abnormal tilt-table testing
    • neurological or psychiatric disorders: evaluation by neurologist or psychiatrist
    • orthostatic hypotension: fall in systolic blood pressure > 20 mmHg on standing having rest supine for 5 mintues
    • carotid sinus hypersensitvity: cardiac asystole lasting 3 sec or more or a fall in systolic bp > 50 mg associated with syncope or presyncope
    • outflow obstruction: severe aortic stenosis: (mean gradient 50 mmHg or more and valvular area 0.9 mm2 or less); hypertrophic cardiomyopahty with outflow obstruction, primary pulmonary hypertension with mean PA pressure at rest 30 mmHg or more or left atrial myxoma or thrombus with protrusion and outflow obstruction
    • pulmonary embolism: positive Doppler ultrasound, lung scan or angiography
    • arrhythmias: sinus pause 3 sec or more; sinus bradycardia 35 bts/min or less; AF with slow ventricular response (RR interval 3 sec or more); SVT for 30 sec or more at 180 bts/min or more or associated with hypotension; Mobitz-II AV block or complete AV block; symptomatic or sustained VT, and nonsustained VF for at least 5 sec
    • electrophysiologic studies were performed if previous MI with ejection fraction 40% of less; bifascicular block, late potentials on signal-averaged ECG with previous MI, and non-invasive ECG monitoring suggesting sinus node dysfunction or AV block. Considered abnormal if prolonged corrected sinus node recovery time (550 msec or more); prolonged H-V interval (100 msec or more); SVT 180 bts/min or more or associated with hypotension; sustained VT; or spontaneous or induced infra-Hisian block
Diagnostic test: Patients underwent a standardised examination including a complete history, physical and neurological examination; blood tests (haematocrit, CK, glucose); 12-lead ECG; testing for orthostatic hypotension; and bilateral carotid sinus massage in patients without contraindications. Patients were then classified into 3 groups
  • cause strongly suspected based on disease-specific diagnostic criteria
  • cause suspected by clinical features, but required further confirmation with a specific investigation (e.g. echocardiography for aortic stenosis)
  • undetermined cause: patients underwent 24-hour Holter monitoring, echocardiography, continuous-loop event recorder, signal-averaged ECG, and passive upright tilt-testing. Selected patient underwent electrophysiogic testing.

The evidence


differential diagnosis number of patients prevalence
(95% CI)
cardiac causes 69 11%
(8.2% to 13%)
arrhythmias 44 6.8%
(4.8% to 8.7%)
acute coronary syndrome 9 1.4%
(0.5% to 2.3%)
aortic stenosis 8 1.2%
(0.4% to 2.1%)
pulmonary embolism 8 1.2%
(0.4% to 2.1%)
vasodepressor syncope 456 70%
(66% to 74%)
orthostatic hypotension 242 37%
(34% to 41%)
carotid sinus hypersensitivity 158 24%
(21% to 28%)
neurological 6 0.9%
(0.2% to 1.7%)
psychiatric 30 4.6%
(3.0% to 6.2%)
other 9 1.4%
(0.5% to 2.3%)
unknown 92 14%
(11% to 17%)

  • Prevalence of syncope: 788/67837: 1.1% (95% CI: 1.1% to 1.2%)
  • 69% of patients had a cause of syncope strongly suspected (95% CI: 65% to 72%). 10% (95% CI: 8% to 13%) had a cause suspected but requiring further diagnostic testing - a cause was found in 73%. 24% had an undetermined cause (95% CI: 21% to 27%) - a probable cause was found in 25% of patients receiving the work-up

Citation

  1. Sarasin FP, Louis-Simonet M, Carballo D, et al: prospective evaluation of patients with syncope: a population-based study. Am J Med 2001; 111 : 177-184
Search Terms: from ACP Journal Club
Contributor: Chris Ball, May 2002
Reviewer:

Clinical Question.
Patient syncope
Intervention or Exposure standardised work-up
Outcome cause