SYNCOPE IN PATIENTS WITH SEVERE AORTIC STENOSIS: More than only an obstructive issue.

BACKGROUND: Severe aortic stenosis (AoS) is considered a primary cause of syncope. However, other mechanisms may be present in these patients and accurate diagnosis can have important clinical implications. The aim of this study is to assess the different etiologies of syncope in patients with severe AoS and the impact of attaining a certain or highly probable diagnosis for the syncope on prognosis. METHODS: Out of a cohort of 331 patients with AoS and syncope, 61 had severe AoS and were included in the study. Main cause of syncope and adverse cardiac events were assessed RESULTS: In 40 patients (65.6%), we reached a certain or highly probable diagnosis of the main cause of the syncope. AoS was considered the primary cause of the syncope in only 7 patients (17.5% of the patients with known etiology). AV block (14p (35.0%)) and vasovagal syncope (6p (15.0%)) were the most frequently diagnosed etiologies. The presence of a known etiology for syncope during the admission was not associated with a lower incidence of recurrence during follow-up (HR 0.69; 95% CI 0.20-2.40). Syncope of unknown etiology was independently associated with greater mortality during 1-year follow-up (HR 5.4; 95% CI 1.3-21.6) and 3-year follow-up (HR 3.5; 95% CI 1.2-10.3). CONCLUSIONS: In a high proportion of patients with severe aortic stenosis admitted for syncope, the valvulopathy is not the main cause of the syncope. Syncope in two thirds of this population is caused by either bradyarrhythmia or reflex causes. Syncope of unknown etiology is associated with increased short- and medium-term mortality, independently of treatment of the valve disease. An exhaustive workup should be conducted to determine the main etiology for syncope.