The Syncope Prophecy

There has been a lot of research regarding the disposition of patients with syncope from the Emergency Department. Unfortunately, to put it bluntly, little of it is effectively usable in general practice. The most recent AHA Syncope guidelines offer loose guidance patients should have risk-stratification performed prior to disposition, but their summary of decision-instruments admits the limitations of each.

And, as it turns out, we know better, anyway.

In this prospective study, Emergency Physicians explicitly recorded the suspected etiology of syncope at the time of disposition, choosing from four broad categories: vasovagal, orthostatic hypotension, cardiac, other/unknown. Physicians were also asked to rate their level of confidence regarding their diagnosis on a scale from 0% to 100%. Research personnel then performed typical observational follow-up to determine 30-day adverse outcomes.

Over the ~4 year study period, 5,010 patients were included in the final analysis. The average age was 53 years, with a wide standard deviation of 23 years. Generally speaking, most patients were healthy, with hypertension the most prevalent known underlying medical condition at 31.6%. Over 90% of patients had ECG and blood testing in the ED, with a minority receiving any radiography. Over half (53.3%) of the cohort received a provisional diagnosis of vasovagal syncope, with 32.2% “other/unknown”, 9.1% orthostatic hypotension, and 5.4% cardiac causes.

The good news: only 1.0% of the vasovagal cohort had an adverse outcome within 30 days, none of which were death. Then, as expected, 20.9% of the cohort with suspected cardiac cause suffered a serious outcome, although, only 0.8% died – an actuarially interesting statistic, considering the average age of this cohort was 86.5 years. The other large cohort of patients, those with “unknown” etiology, suffered serious outcomes 4.8% of the time, and their outcomes were spread evenly across the various cardiac and non-cardiac outcomes.

A long story short, then – physicians do a pretty good job of identifying those who are at low risk and high risk for serious outcomes.  Considering the imprecision of decision instruments and their limitations, it turns out the best computer … is probably still the trained brain.  These data don’t have quite the granularity to decipher whether the low rates of adverse outcomes in the “other/unknown” cohort were otherwise related to specific diagnoses or underlying comorbidities, but it’s not a stretch to speculate physicians probably could also have prognosticated fairly well on gestalt even within this category.

Worth noting, as well, in comparison to the PESIT study, the prevalence of undiagnosed pulmonary embolism in this population was 0.2%.

“Syncope Prognosis Based on Emergency Department Diagnosis: A Prospective Cohort Study”

https://www.ncbi.nlm.nih.gov/pubmed/29136314

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