Syncope and COVID-19 disease - A systematic review.

BACKGROUND: Syncope is not a common manifestation of COVID-19, but it may occur in this context and it can be the presenting symptom in some cases. Different mechanisms may explain the pathophysiology behind COVID-19 related syncope. In this report, we aimed to examine the current frequency and etiology of syncope in COVID-19. METHODS: A systematic review across PubMed, ISI Web of Knowledge and SCOPUS was performed, according to PRISMA guidelines, in order to identify all relevant articles regarding both COVID-19 and syncope. RESULTS: We identified 136 publications, of which 99 were excluded. The frequency of syncope and pre-syncope across the selected studies was 4.2% (604/14,437). Unexplained syncope was the most common type (87.9% of the episodes), followed by reflex syncope (7.8% of the cases). Orthostatic hypotension was responsible for 2.2% of the cases and syncope of presumable cardiac cause also accounted for 2.2% of cases. Arterial hypertension was present in 52.0% of syncope patients. The use of angiotensin receptor blockers or angiotensin converting enzyme inhibitors were not associated with an increased incidence of syncope (chi-square test 1.07, p 0.30), unlike the use of beta-blockers (chi-square test 12.48, p < 0.01). CONCLUSION: Syncope, although not considered a typical symptom of COVID-19, can be associated with it, particularly in early stages. Different causes of syncope were seen in this context. A reevaluation of blood pressure in patients with COVID-19 is suggested, including reassessment of antihypertensive therapy, especially in the case of beta-blockers.

Syncope and silent hypoxemia in COVID-19: Implications for the autonomic field.

Coronavirus-19 (COVID-19), the infectious disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus, has wreaked havoc across the globe since its emergence in December 2019. Reports of patients presenting with syncope and pre-syncope, as well as hypoxemia without symptoms of dyspnea ("silent hypoxemia"), have led researchers to speculate whether SARS-CoV-2 can alter autonomic nervous system function. As viral infections are commonly reported triggers of altered autonomic control, we must consider whether SARS-CoV-2 can also interfere with autonomic activity, at least in some patients. As we are still in the early stages of understanding COVID-19, we still do not know whether syncope and silent hypoxemia are more strongly associated with COVID-19 compared to any other viral infections that severely compromise gas exchange. Therefore, in this perspective we discuss these two intriguing clinical presentations, as they relate to autonomic nervous system function. In our discussion, we will explore COVID-specific, as well as non-COVID specific mechanisms that may affect autonomic activity and potential therapeutic targets. As we move forward in our understanding of COVID-19, well-designed prospective studies with appropriate control and comparator groups will be necessary to identify potential unique effects of COVID-19 on autonomic function.