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Re: Validation of the San Francisco Rule

Though Dr Sreenivasan states the San Francisco syncope rule is a very sensitive rule with a 98% sensitivity, due to the relatively small number of patients with the outcome of interest, the lower estimate of sensitivity is 89%, potentially missing 11% of patients with a serious cause of syncope. It must also be remembered that this was a single site validation study, the results may not be generalisable to our practice. Finally the reason why we often write collapse cause, is that after our diagnostic work up the diagnosis is often not clear. After reading the medical discharge letters sent to us it appears the in - patient teams are often not sure either, as we frequently see patients discharged with a diagnosis of collapse cause.

In summary this decision rule is a useful basis for us to make disposal decisions for patients presenting with a snycopal episode, however further research is required to validate the rule in different populations.

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Re: Carotid Sinus Hypersensitivity is a common cause of unexplained syncope in patients aged over 50

Dear Editor,

We applaud Reed and Gray’s efforts at reviewing the literature on the management of syncope in the emergency department [1]. We are, however, uncomfortable with the suggestion that carotid sinus massage (CSM) could be performed as part of the routine clinical examination for syncope within the emergency department.

Carotid sinus hypersensitivity (CSH) is characterised by reduction in systolic blood pressure of at least 50 mmHg (vasodepressor) as well as the cardioinhibitory (asystole of 3 seconds or more) mentioned in the above review. Only 50% of attacks are associated with neck movements. It is rare before the age of 50 but has been found to reproduce syncope in 26-60% of patients with unexplained syncope [2]. While this is probably an overestimate, carotid sinus syndrome is likely to be a more common cause than is widely accepted. Up to 25% of all permanent pacemaker implants in centres with an interest in this disorder are for carotid sinus syndrome [3].

We feel that CSM should only be performed with appropriate monitoring on a tilt-table, as 30% of CSH is only diagnosed with upright CSM [4]. CSM does involve a 0.17- 0.45% risk of neurological complications. The presence of carotid bruit is a poor indicator of severity of carotid stenosis. CSM should therefore also be avoided in patients who have had a transient ischaemic attack or stroke within the last 3 months and in patients with any history of ventricular tachyarrhythmia.

References

1. Reed MJ, Gray A. Collapse query cause: the management of adult syncope in the emergency department. Emergency Medical Journal 2006;23:589 -594.

2. Puggioni E, Guiducci V, Brignole M, Menozzi C, Oddone D, Donateo P, et al. Results and complications of the carotid sinus massage performed according to the "method of symptoms". American Journal of Cardiology 2002;89(5):599-601.

3. Bexton RS, Davies A, Kenny RA. The rate-drop response in carotid sinus syndrome: the Newcastle experience. Pacing & Clinical Electrophysiology 1997;20(3 Pt 2):840.

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Re: Prospective validation of the San Francisco Syncope Rule

Dear Editor,

Since this excellent review by Reed and Gray was accepted for publication on 13 March 2006, Quinn et al. have published a prospective validation of their San Francisco Syncope Rule (Quinn JV, McDermott DA, Steill IG, et al. Prospective Validation of the San Francisco Syncope Rule to Predict Patients With Serious Outcomes. Ann Emerg Med. 2006; 47:448 - 454). This showed 98% sensitivity and 56% specificity in predicting serious outcomes from ED presentations with syncope and presyncope.

I find the title "Collapse query cause" ironic, as this is often written on the paramedic sheet, as well as on the ED and junior medical clerking as both the presenting complaint and final diagnosis, without any critical thought processes in between.