Syncope: a clinical prediction rule can indicate which patients are at high risk of arrhythmias and death.

Clinical bottom line (level 1a)

  1. Arrhythmias and death are common in patients with syncope over the next year.
  2. Both are more common in patients with three or more of:
    • abnormal ECG
    • history of ventricular arrhythmias
    • history of congestive heart failure
    • aged >45
  3. Both are uncommon in patients with none of these risk factors.
Martin et al: Annals of Emergency Medicine 1997; 29 (4): 459-466
Expires October 2004

The study

Setting: emergency department, university hospital, USA

626 patients (aged range 15 to 94 years; mean 57, 54% female) syncope (sudden transient loss of consciousness with inability of maintain postural tone and not caused by a seizure, vertigo, dizziness, coma, shock or other altered states of consciousness). Derivation cohort:: 252 55%: female: aged 15 -90; mean 57; Validation cohort: 374 patients : 53% female; aged 18 to 94; mean 56

Excluded if
  • failed to regain consciousness spontaneously
  • pharmacological or electrical therapy required initially


    • All patients had history and examination, blood count, U&E, Cr, glucose, urinalysis, a 12-lead ECG and 24 hours ECG monitoring. Patients had further investigations as indicated.
    Independent blinded reference standard, applied in all patients from a consecutive appropriate spectrum.
    Diagnostic test: clinical prediction guide
    • Patients were followed for 3 years.
    • Outcome: 1. arrhythmias
      • ventricular tachycardia for three beats or more
      • sinus pause > two seconds with symptoms
      • symptomatic sinus bradycardia (dizziness, light-headed, syncope, or documented arrhythmia)
      • SCT with symptoms or systolic bp , 90 mmHg
      • AF
      • complete heart block or Mobitz II
      • pacemaker malfunction
      • prolonged sinus mode recovery time on electrophysiologic testing
      2. death - confirmed by contacting family, patient's physician or autopsy
    • Abnormal ECG defined as:
      • AF or flutter
      • multifocal atrial tachycardia
      • junctional or paced rhythm
      • frequent or repetitive PVC (including VT)
      • conduction disorder: LAD, BBB, intraventricular delay
      • LVH, RCH
      • PR interval < 0.10 mm
      • old MI
      • Mobitz I with other abnormalities, Mobitz II or complete heart block

    The evidence

    pre-test probability of derivation set: death: 16%, (95% CI: 11% to 20%)
    pre-test probability of validation set: death: 11%, (95% CI: 8.0% to 14%)
    pre-test probability of arrhythmia: 26%, (95% CI: 21% to 31%)
    pre-test probability of arrhythmia within a year: 14%, (95% CI: 10% to 17%)

    diagnostic test dead at one year not dead LR+
    (95% CI)    		 post-test probability LR-
    (95% CI)    		 post-test probability
    3 or 4 risk factors 17 29 3.2
    (1.9 to 5.2)     		37% 0.65
    (0.49 to 0.87)     		11%
    2 18 68 1.4
    (0.97 to 2.1)     		21% 0.79
    (0.59 to 1.1)     		13%
    1 3 60 0.27
    (0.09 to 0.82)     		5% 1.3
    (1.1 to 1.5)     		19%
    0 1 54 0.10
    (0.01 to 0.70)     		2% 1.3
    (1.2 to 1.4)     		19%
    total 39 211


    diagnostic test dead at one year not dead LR+
    (95% CI)    		 post-test probability LR-
    (95% CI)    		 post-test probability
    3 or 4 risk factors 9 24 3.0
    (1.5 to 5.9)     		27% 0.85
    (0.72 to 0.99)     		10%
    2 23 119 1.5
    (1.1 to 2.1)     		16% 0.71
    (0.50 to 0.99)     		8%
    1 9 99 0.72
    (0.39 to 1.3)     		8% 1.1
    (0.94 to 1.3)     		12%
    total 42 332


    diagnostic test arrhythmia within a year no arrhythmia LR
    (95% CI)    		 post-test probability
    3 or 4 risk factors 29 17 4.9
    (2.9 to 8.2)     		63%
    2 25 61 1.2
    (0.8 to 1.7)     		29%
    1 8 55 0.41
    (0.21 to 0.82)     		13%
    0 3 52 0.16
    (0.053 to 0.51)     		5%
    total


    diagnostic test arrhythmia within a year no arrhythmia LR
    (95% CI)    		 post-test probability
    3 or 4 risk factors 15 18 5.3
    (2.8 to 9.8)     		45%
    2 26 116 1.4
    (1.0 to 1.9)     		18%
    1 7 101 0.44
    (0.22 to 0.89)     		6%
    0 3 88 0.22
    (0.071 to 0.66)     		3%
    total

    • risk factors for death or arrhythmia at one year:
      • abnormal ECG: OR 3.2 (1.6 to 6.4)
      • history of ventricular arrhythmias: OR 4.8 (1.7 to 14)
      • history of congestive heart failure: OR 3.1 (1.3 to 7.4)
      • aged >45: OR 3.2 (1.3 to 8.1)

    Comments

    1. Would benefit from being tested in other situations.

    Citation

    1. Martin TP, Hanusa BH, Kapoor WN: Risk stratification of patients with syncope. Annals of Emergency Medicine 1997; 29 (4): 459-466
    Contributor: Chris Ball and Clare Wotton, October 2000
    Reviewer:

    Clinical Question.
    Patient syncope
    Intervention or Exposure risk factors
    Outcome arrhythmia