The Relationship Between Syncope and Cardiac Index in Acute Pulmonary Embolism

Abstract

The relationship between syncope and invasive hemodynamics in patients with pulmonary embolism (PE) remains unknown. The objective of this study was to assess the ability of syncope, as a single clinical variable, to predict a low cardiac index in patients with acute PE. This retrospective study included patients with acute intermediate- and high-risk PE who underwent catheter-based therapies between October 2020 and June 2024. The primary outcome was whether syncope at hospital presentation was a predictor of low cardiac index (≤2.2 L/min/m²) in patients with acute intermediate or high risk PE. Secondary outcomes included 30-day mortality, hemodynamic instability, 90-day readmission rates, other invasive hemodynamic parameters, intensive care unit (ICU) length of stay (LOS), and hospital LOS. Regression analyses were used to evaluate the association between cardiac index and syncope. A total of 132 patients (86% intermediate- and 14% high-risk) were included in the study, with 27 (20%) presenting with syncope. Among the 114 intermediate-risk patients, 24 (21%) presented with syncope. In all-comers, there was no significant difference between groups at baseline. Within the intermediate-only subgroup, there were no significant differences between groups at baseline, except that the syncope group was older (62.6 ± 14.9 vs 56.1 ± 13.9, p = 0.048, Table 2) and had significantly higher troponin elevation at presentation (684.3 ± 1361.8ng/L vs 195.6 ± 278.1ng/L, p = 0.003, Table 2). In all-comers, there was no difference in rates of low cardiac index (63% vs 59%, p = 0.71) or mPAP (33.9 ± 8.6 vs 32.7 ± 9.6 mm Hg, p = 0.57) between patients who presented with and without syncope. Similarly, among intermediate-risk patients, there was also no difference in the rates of low cardiac index (67% vs 57%, p = 0.38) or mPAP (34.0 ± 9.2 vs 33.1 ± 9.8 mmHg, p = 0.69) between patients with and without syncope. There was no difference in clinical outcomes between those who presented with and without syncope. In conclusion, in patients with acute PE, syncope was not associated with a low cardiac index or higher mPAP.