Is Presyncope as Serious as Syncope?

Aug 01, 2024

Syncope has three components: (15 minutes read)

Loss of consciousness
Loss of postural tone and
Return to baseline

Patients with syncope comprise about 1% of all Emergency Department(ED) presentations. The cause may be benign, however there are a proportion of patients that have serious causes ie., cardiac causes, which may be associated with significant morbidity and mortality. There is also the burden of potential trauma that may be associated with the collapse. Further, we may find ...

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Syncope has three components: (15 minutes read)

Loss of consciousness
Loss of postural tone and
Return to baseline

Is presyncope the same as syncope in terms of risks? Although we consider presyncope to be part of the same disease spectrum as causes syncope, we know that less patients with pre-syncope are admitted. We really have little guidance in the literature on the pre-syncope patient.

Mirfazaelian et al (1) performed a synthesis of the literature and looked at short-term serious outcomes among ED patients with pre-syncope and compared them to those with syncope. They hypothesized that "syncope and presyncope are on the same spectrum of disease and carry the same risk of serious outcomes".

What They Did

This was a systematic review of the literature to determine outcomes of patients who presented with pre-syncope to the ED.

They included:

Original studies (observational and interventional) of adult patients who presented with presyncope and/ or syncope to the ED.
Studies with reported outcomes among presyncope patients.
They excluded Non–peer-reviewed articles, letter to editor, and case reports.

From the original 1880 articles identified in the search strategy, only 5 studies (2-6) were included in the systematic review. There was one retrospective and four prospective studies. They all looked at short term (30 day) outcomes, with one study also looking at 6 month outcomes. The numbers of patients with presyncope in each trial varied from the smallest study (which was retrospective) of 83 patients, to the largest study, which was a multicenter study with 1380 patients.

What They Found

Patients with presyncope have similar short term serious outcomes as those with syncope.
- Short term serious outcomes occurred in 4% to 27% of patients.
The most common serious outcome was arrhythmia.
- Supraventricular arrhythmias were the most common.
- Ventricular arrhythmias occurred in up to 7% of patients.
Other cardiac abnormalities included:
- Sinus node dysfunction in up to 12%
- New uncontrolled atrial fibrillation in up to 15%
- Myocardial infarction in up to 12%
Anaemia/Haemorrhage was the second most serious cause

My Take on This Study and Does it Change my Practice

This is a systematic review with some limitations including:

It contained a restropective study
The inclusion and exclusion criteria amongst studies differed
There was a high risk of bias
All data could not be pooled

My current practice is to approach all presyncope patients as I do syncope patients. This study is of interest to me as it reinforces the concern that I have for the potential for arrhythmias causing pre-syncope/syncope. The results of this study do not indicate that pre-syncope is benign. I will continue to treat patients in the same way, whilst awaiting the definitive study.

References

Mirfaszaelian H et al. Serious outcomes among emergency department patients with pre-syncope: A systematic review. Acad Emerg Med 9 June 2024. Ahead of Print https://doi.org/10.1111/acem.14943 PMID: 38853536.
Sun BC, et al. Predictors of 30-day serious events in older patients with syncope. Ann Emerg Med. 2009;54(6):769-778.e5.
Grossman SA, et al. Do outcomes of near syncope parallel syncope? Am J Emerg Med. 2012;30(1):203-206.
Greve Y, et al. The prevalence and prognostic significance of near syncope and syncope: a prospective study of 395 cases in an emergency department (the SPEED study). Dtsch Arztebl Int. 2014;111(12):197.
Thiruganasambandamoorthy V, et al. Outcomes in presyncope patients: a prospective cohort study. Ann Emerg Med. 2015;65(3):268-276. e6.
Bastani A, et al. Comparison of 30-day serious ad- verse clinical events for elderly patients presenting to the emer- gency department with near-syncope versus syncope. Ann Emerg Med. 2019;73(3):274-280.