What does presyncope mean to you?
If you ask this question to a handful of doctors you’ll get a multitude of different answers, you’ll also get a huge variety of opinion as to their understanding of it’s significance or associated morbidity and mortality. As with most areas of greyness in medicine this is contributed to significantly by a paucity of evidence on the topic.
Syncope by comparison has had a significant amount more published on the topic but a significant number of the studies include patients that had presyncopal rather than true syncopal event. We covered the San Francisco Syncope Rule a while back and it’s worth reminding ourselves of the paper as it’s one of the most commonly quoted papers on the topic.
The problem with presyncope is understanding it’s importance, significant precipitants and then understanding what we as EM clinicians can do to improve this risk/outcomes for patients. Our patterns of practice vary significantly on the topic and this is in part due to our tolerance of risk in our diagnostic evaluation.
A recent paper from the Annals of Emergency Medicine is a significant step forwards on the topic and although it carries it’s own limitations it helps us to understand the presentation to a greater degree and should therefore help to inform and improve our practice
Who did they look at?
A prospective cohort of consecutive patients presenting to 2 large EDs in Canada between October 2010 and august 2012
- ≥16 years old
- Experiencing presyncope as defined by ≥1 of the following prodromal symptoms of syncope
o Visual symptoms of a short duration (a few seconds to minutes)
o Previously enrolled in the study
o Those experiencing
o Loss of consciousness
o Change in mental status following the event
o Obvious witnessed seizure
o Significant trauma requiring admission
o Head injury preceding the event
o Intoxicated patients & those under the influence of illicit drugs
o A language barrier preventing the assessment
What information did they collect?
o Patient demographics
o An estimate of the clinician’s confidence in assigning a cause for the episode of presyncope, on an 11 point scale
o An estimate if the prediction of a 30 day serious outcome, on a 13 point scale
What did they look to find?
o To determine the frequency of ED presyncope visits, management of presyncope, 30 day outcomes and the accuracy of Emergency Physicians’ serious outcome prediction
How did they define serious outcomes?
o Arrhythmias > 30 seconds
o Serious structural heart disease – tight aortic stenosis, hypertrophic cardiomyopathy, left atrial myxoma, pericardial effusion with ventricular wall motion abnormalities or pericardial tamponade
o Aortic dissection
o Severe pulmonary artery hypertension
o Significant haemorrhage
o Any other serious condition that will require treatment and will cause the patient to return to the ED if not detected
o Procedural interventions e.g. pacemaker insertion
How did they gather this information?
o By review of the electronic patient records at the study hospitals and a 30 day telephone follow up
What did they find?
o 0.5% of ED attendances were to due to presyncope
o 4.7% of patients presenting with presyncope were admitted
o 5.1% of patients with presyncope experienced serious 30-day outcomes
o There were 2 deaths (0.2%), both of which occurred outside the hospital due to unknown causes
What does this mean for us?
The generalizability of this study to our population is questionable; the study was only carried out in 2 large ED’s in Canada. The admission rate would seem relatively low at 4.7% and it is difficult to say how similar that is to our practice.
The inclusion criteria and definition of presyncope also seems relatively broad, with patients only required to have symptoms such as weakness or sweating. These could be regarded as relatively soft and broad inclusion criteria and may also decrease the rate of serious 30-day outcome rates, but this cannot be proven.
What is interesting to consider is the 30-day serious outcome rate in comparison with the cohort from the San Francisco Syncope Rule validation study (SSRV) and this may surprise many that it is not wildly different, 5.1% vs 7.4% in the SSRV.
When you consider a patients with presyncope you probably have a cardiac event high up on your list of differentials to exclude as a precipitant, this paper would seem to consolidate that with two thirds of the patients with a serious outcome attributed to a cardiac cause, the next largest categories were then anaemia or significant haemorrhage.
So putting this all together what have I taken away from the study?
Presyncope may not be as benign as you think especially when compared to full blown syncope. There is a serious outcome rate of approx. 1:20. The majority of the causes can be identified in ED so your evaluation IS important and remember to focus upon cardiovascular/arrhythmogenic symptoms, signs and risk factors and also the importance of exploring the potential for bleeding and anaemia should be emphasised
We’re not good at determining patients risk of a 30-day serious outcome and we need to find ways to improve this but in the meantime should concentrate our efforts upon the areas that we know make a difference.
I look forward to your feedback and comments