Author + information
- A. Fedorowski,
- F. Ricci,
- S. Palermi,
- G. Renda,
- S. Gallina,
- O. Melander,
- R. De Caterina and
- R. Sutton
Cardiac syncope heralds significantly higher mortality compared with syncope due to non-cardiac causes or unknown aetiology, which is commonly considered a benign event. Nonetheless, previous studies have typically investigated the outcome of syncope across different aetiological subgroups, rather than compared matched group of patients with and without syncope. Therefore, little is known about prognosis of patients with history of non-cardiac syncope compared with syncope-free population.
To determine whether non-cardiac syncope is associated with increased mortality.
We performed a systematic review of the literature by searching for prospective observational studies reporting multivariable adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for all-cause mortality in participants with history of non-cardiac syncope (regardless of site of presentation, i.e. inpatient or outpatient) compared with syncope-free participants. Hazard ratios were pooled in a random-effect, generic inverse variance meta-analysis in order to compute summary effect size.
We identified a total of 4 studies, including an overall population of 287,382 individuals (51.6% men; age, 64.5±12.4 years), 38,843 with history of non-cardiac syncope and 248,539 without history of syncope. The average follow-up was 2.9 years. Compared with controls, history of non-cardiac syncope was associated with increased all-cause mortality (pooled adjusted HR 1.13; 95%CI 1.05-1.23).
Non-cardiac syncope is associated with higher all-cause mortality in older adults.
Search methods for identification of studies
Medline and Embase databases, the Clinical Trials Registry (www. clinicaltrials.gov), as well as abstracts from major cardiological and neurological societies meetings were searched for potentially relevant articles using the search terms ((syncope OR vasovagal OR neuron mediated OR loss of consciousness OR faint OR lipothymia)) AND ((follow OR cohort OR mortality OR prognosis OR outcome OR death)). We also searched reference lists of all identified articles for additional relevant studies, including hand-searching reviews and previous meta-analyses.