Syncope as the Sole Manifestation of a Saddle Pulmonary Embolism in a Hemodynamically Stable Patient

Syncope is a common emergency department presentation with many potential causes. Pulmonary embolism (PE) typically presents with chest pain, dyspnea, and abnormal vital signs, but has been reported without typical signs or symptoms. A 77-year-old man experienced sudden syncope while carrying water cartons. He denied prodromal symptoms or cardiopulmonary complaints. His history included hypertension, chronic kidney disease, glaucoma, and hyperlipidemia. However, he denied major risk factors for PE. On arrival, he was hemodynamically stable, with only a forehead abrasion on exam. Labs revealed thrombocytopenia (89 × 10³/μL) (reference range: <150 x 10³/μL), elevated troponin (120 ng/L) (reference range: <40 ng/L), and B-type natriuretic peptide (BNP) (374 pg/mL) (reference range: <125 pg/mL). Electrocardiogram revealed new right heart strain, while the chest radiograph was unremarkable. CT pulmonary angiography confirmed acute saddle PE with a large clot burden. He was anticoagulated and admitted, but developed hemodynamic instability within 24 hours, requiring catheter-directed thrombectomy. He stabilized and was discharged on hospital day 6, on oral anticoagulation. This case underscores that PE can present as isolated syncope, highlighting the importance of considering subtle clinical and laboratory clues.