Lifetime prevalence of syncope: the HELIUS study

Abstract

Abstract Background Syncope is a common presentation to emergency departments. Cardiovascular risk differs markedly among ancestry groups, but data on syncope are scarce. Fundamental understanding of the determinants of syncope in the population might aid in the risk stratification of syncope in acute settings. Purpose To assess lifetime prevalence of syncope and its determinants in the general population. Methods We included 14937 adults (18–70 y) randomly sampled in the cross-sectional Healthy Life in an Urban Setting (HELIUS) population study, stratified by White-European, Asian, Turkish, Moroccan, and West-African ancestry. We assessed syncope history, body mass index (BMI), blood pressure (BP), supine stroke volume (SV), cardiac contractility (dP/dt), cardiac output (CO), systemic vascular resistance (SVR), and resting plasma activity of CK, an ATP-generating enzyme that facilitates cardiovascular contractility and sodium retention, counteracting hypotensive susceptibility. Results Mean age of the participants (39% men) was 43.3 y (SD 12.9). Lifetime prevalence of syncope was significantly higher in women (31%) vs. men (18%); and in White-European (34%) and other ancestries (25 to 28%), vs. West-African ancestry (19%) (Figure 1). Mean age at first syncope was 24 y (SD 13). Participants without syncope history had higher BP (systolic, +29% SD), BMI (+17% SD), CK (+31% SD) (Figure 1), modestly higher SV, dP/dt, and CO (+6 to 8% SD), and more diabetes (5.2 vs 3.6%). The main protective predictors of syncope were West-African ancestry (0.59 [0.54 to 0.65]), male sex (0.52 [0.48 to 0.57]), and CK (0.56 [0.46 to 0.69]/log CK increase), with high CK in men and West-African ancestry largely explaining the low syncope prevalence in these groups. Conclusion To our knowledge the first population study on syncope by ancestry indicates that the lifetime prevalence is high in White-European women, and low in person of African ancestry. The inverse association of syncope with the pressor enzyme CK needs further study. Funding Acknowledgement Type of funding sources: None. Figure 1. Syncope by Sex, Ancestry, and CK