Epidemiology and Outcomes of Acute Pulmonary Embolism in Seychelles: A National Cohort Study With a Subgroup Analysis of Systemic Thrombolysis Efficacy and Safety in Intermediate-Risk Pulmonary Embolism.

Background Pulmonary embolism (PE) is an important cause of cardiovascular morbidity and mortality worldwide. Data from Small Island Developing States (SIDS) in Africa are limited. This study describes the epidemiology of acute PE in Seychelles and examines outcomes associated with different management approaches in patients with intermediate-risk PE. Methods This retrospective observational cohort study was conducted at Seychelles Hospital, Victoria, the national tertiary referral hospital and principal public healthcare facility in the Republic of Seychelles. We conducted a retrospective observational cohort study of all adults with confirmed acute PE managed in Seychelles between January 1, 2019, and December 31, 2025. Temporal trends in incidence, mortality, and hospital length of stay were evaluated. An exploratory subgroup analysis was performed in patients with intermediate-risk PE managed between January 1, 2019, and May 31, 2026, to assess clinical outcomes across this heterogeneous cohort. Patients were grouped according to treatment strategy: systemic thrombolysis followed by anticoagulation (Group A; n = 48) or anticoagulation alone (Group B; n = 12). Clinical, physiological, echocardiographic, and safety outcomes were assessed. Results A total of 389 patients with acute PE were identified during the study period. Females accounted for 231 (59.4%) cases and males for 158 (40.6%). Annual case numbers increased from 36 in 2019 to 84 in 2024 before decreasing to 69 in 2025. Overall crude mortality was 7.5% (29/389), ranging from 20.0% in 2020 to 0.0% in 2025. Among patients with intermediate-risk PE, the observed survival was higher in the thrombolysis group than in the anticoagulation-only group (47/48 (97.9%) vs. 8/12 (66.7%); p = 0.0045). In the thrombolysis group, 32 patients out of the 48 received tenecteplase in myocardial infarction dose as a thrombolytic agent and 16 patients received alteplase. Significant improvements were observed following thrombolysis in oxygen saturation (p < 0.001), PaO2/FiO2 ratio (p < 0.00001), and tricuspid annular plane systolic excursion (TAPSE; p = 0.0104). Right ventricular dilatation decreased on follow-up echocardiography (p = 0.0156), and McConnell's sign resolved in all patients with available follow-up studies. One patient (2.1%) experienced intracranial hemorrhage after thrombolysis. Minor bleeding events included self-limited haematuria (n = 11) and gum bleeding (n = 3). Conclusion PE represents a substantial clinical burden in Seychelles. In this retrospective cohort, systemic thrombolysis in selected patients with intermediate-risk PE demonstrated a favorable association with physiological and echocardiographic outcomes, as well as lower observed mortality, compared to anticoagulation alone. These exploratory findings highlight important clinical trends, although the inherent retrospective design limits direct causal evaluations of treatment efficacy. Tenecteplase in the myocardial infarction dosage was associated with good outcomes in treating intermediate-risk PE. We observed successful thrombolysis outcomes within a window time up to seven days.