Sunday, January 2, 2011

Red flags in evaluation of syncope

Syncope is one of the commonest presentation to the ERs....and would require substantial spending if everyone gets a complete work up to diagnose or rule out the causes. It would be reasonable to risk stratify patients and investigate. The first step would be to get the definition of syncope right! ----- It is a transient loss of consciousness due to transient global hypoperfusion of brain. 

Not everyone needs admission or specialist referralUrgent referral or hospital admission for investigation is needed for patients who have chest pain, breathlessness, a history of cardiac disease, family history of sudden death, signs of heart failure, or abnormalities on electrocardiography. The electrocardiography features that suggest cardiac arrhythmias include ventricular tachycardia, a widened QRS complex (>120 ms), sinus bradycardia (<50 beats/min), prolonged or excessively shortened corrected QT interval (>450 ms and < 300 ms, respectively), T wave inversion leads V1–V3, epsilon waves or ventricular late potentials (arrhythmogenic right ventricular dysplasia), and right bundle branch block with ST elevation and T wave inversion in V1–V3 (Brugada syndrome). Patients who report a history of syncope with no warning symptoms (Stokes-Adams attack), syncope during exercise, palpitations preceding syncope, and syncope in the supine position should be investigated by a specialist. People with frequent or injurious syncope or implications for driving also warrant specialist input. Prolonged unconsciousness, confusion after the event, or neurological signs and lateral tongue biting suggest a non-syncopal event, and this should prompt neurological evaluation

To simplify the above, San Fransisco Syncope Rule was developed .SFSR  uses the presence of an abnormal electrocardiogram(any new rythm changes or presence of an abnormal rythm), heart failure(or a c/o shortness of breath), anaemia (haematocrit < 30%), or systolic hypotension (< 90 mm Hg) to identify patients who require urgent action. In the original derivation study, the SFSR had 96% (92% to 100%) sensitivity and 62% (58% to 6%) specificity in identifying patients with short term adverse outcomes. In the study where the SFSR score was validated, it showed a 98% sensitivity and 58% specificity in identifying patients with short term (1 month) mortality. And it had the ability to decrease overall admissions by 7%. A thing to remember in this study..was that the rule was applied after the ER physician has evaluated the patient. So would be optimal for an Internal medicine resident seeing a ER consult.

The reason behind paying special attention to cardiac causes are...cardiac syncope carries a high mortality in all age groups. The Framingham study cohort's age and sex adjusted hazard ratios for death over a mean follow-up of 8.6 years was 2.4 (95% confidence interval 1.78 to 3.26) for cardiac syncope compared with 1.17 (0.95 to 1.44) in the "vasovagal group," which included orthostatic hypotension. 
Have a look at the American College of Cardiology recommendations on evaluation of syncope.