Syncope as a presentation of acute pulmonary embolism

Syncope is an atypical presentation for acute pulmonary embolism (APE). There are conflicting data concerning syncope and prognosis of APE.

One hundred and seventy-nine consecutive patients aged 22-96 years (median, 68 years) with APE were retrospectively enrolled in the study.

Prevalence of syncope was 13% (n=23) at the time of presentation. Compared to patients without syncope, those with syncope had a higher rate of central embolism (83% vs 43%, respectively, P=0.002), right ventricular dysfunction (91% vs 68%, P=0.021), and troponin positivity (80% vs 39%, P=0.001) but not 30-day mortality (13% vs 10%, P=0.716). Multivariate analysis showed that central localization (odds ratio: 9.08) and cardiac troponin positivity (odds ratio: 4.67) were the independent correlates of the presence of syncope in the patients with APE. Frequency of cardiopulmonary disease was lower, and duration from symptom onset to hospital admission was shorter in patients with syncope (P=0.138 and 0.118, respectively), although not significant.

Syncope most likely represents an intermediate condition between massive APE and hypotension. In APE patients with syncope, the prognosis seems to depend on the underlying pathology, the patient's age, comorbidities and duration from symptom onset to hospital admission, and the use of thrombolytic therapy.