Pulmonary embolism presenting as syncope: case report and review of the literature.

Syncope as an initial presentation of pulmonary embolism occurs in about 10% of patients. A 68-year-old woman was admitted to the hospital with syncope. A right lower lobe infiltrate was found on a chest x-ray film, and results of a ventilation-perfusion scan were interpreted to mean that a high probability of pulmonary embolism existed. Other causes of syncope were excluded. A Doppler scan of the lower extremities revealed deep venous thrombosis. Intravenous heparin was administered, and then an inferior vena cava filter was placed to prevent pulmonary embolism from recurring. The patient has been well for 16 months since that episode. A review of 20 case reports in the literature of 10 women and 10 men with pulmonary embolism presenting as syncope revealed that female patients were younger than male patients and that the outcome was fatal in 40% of all cases. Syncope as a presenting symptom of pulmonary embolism is difficult to diagnose. Physicians must be vigilant with patients who have syncope, because this symptom may be the "forgotten sign" of life-threatening pulmonary embolism. The need for prompt diagnosis is clear, because with appropriate treatment the majority of patients may survive.