Syncope as the Initial Presentation of Severe Pulmonary Embolism Without Hypoxemia: A Clinical Case.

Syncope and pulmonary embolism (PE) are common presentations in emergency medicine. While syncope is a recognized but rare manifestation of acute PE, it is exceptionally the sole initial symptom of PE. This case highlights the diagnostic and therapeutic challenges of such atypical presentations. We present the case of a 71-year-old man admitted to the emergency department for isolated syncope. He was initially hypotensive, with no hypoxemia, chest pain, or dyspnea. Clinical examination and bedside echocardiography revealed signs of right ventricular (RV) dysfunction, leading to the diagnosis of high-risk pulmonary embolism. The diagnosis was confirmed by computed tomography pulmonary angiography (CTPA). The patient, with high-risk PE, underwent systemic thrombolysis. He required a brief hospitalization for monitoring in the intensive care unit (ICU) and has successfully recovered clinically. This case illustrates the potential severity of PE presenting with isolated syncope and the value of focused cardiac ultrasound in emergency settings. Syncope in the context of PE is a major predictor of hemodynamic instability and early mortality. Despite its prognostic value, syncope is not currently integrated into risk stratification algorithms. The management of high-risk PE is guided by European Society of Cardiology (ESC) recommendations and includes systemic thrombolysis in the absence of contraindications. In this case, the patient required thrombolysis due to persistent hypotension. Isolated syncope may be the only symptomatological manifestation of a life-threatening PE. Early recognition and risk-adapted management are critical to improving outcomes. This case highlights the importance of maintaining a high index of suspicion and utilizing point-of-care echocardiography in patients who present with syncope and hypotension.