BACKGROUND: 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. METHODS: 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/m RESULTS: 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. CONCLUSION: In conclusion, in patients with acute PE, syncope was not associated with a low cardiac index or higher mPAP.