Recognition of unprovoked (idiopathic) pulmonary embolism-Prospective observational study

The assessment of the clinical symptoms is the weakest link of the pulmonary embolism (PE) diagnostic algorithm. Despite the presence of highly sensitive and specific imaging methods, verifying PE remains difficult due to nonspecific clinical symptoms and frequently its subclinical course.

The aim of this study is to improve the recognition of PE by investigating the clinical presentation and short-term prognosis of unprovoked PE in comparison to provoked PE. The study was directed to patients who suffer from PE as a primary disease.

This prospective observational study included 331 patients with PE, approved by computer tomographic pulmoangiography. They were categorized as having unprovoked or provoked PE, according to their epidemiological data. The clinical characteristics and one-month mortality rate were compared between both groups.

About 67% of the patients had provoking factors and ∼33% had unprovoked PE. The patients in the unprovoked PE-group were younger compared to provoked PE-group (56.67 ± 17.95 vs 63.76 ± 14.58, p < .0001) and the males predominated vs females (62.04% vs 37.96%, p = .012). The patients with unprovoked PE had more previous thromboembolic events compared to provoked PE-group (30.56% vs 19.45%, p = .022) and a larger thrombotic burden (p = .001). Dyspnea (85.18% vs 85.13%), chest pain (47.22% vs 46.85%), cough (43.92% vs 45.94%), hemoptysis (16.67% vs 14.41%), hemodynamic instability (9.26% vs 8.56%), deep venous thrombosis (49.51% vs 44.5%) had similar frequencies in both groups. No significant differences in the means of systolic pressure of arteria pulmonalis, D-dimer, arterial blood gases, Revised Geneva probability score were found. One-month mortality was lower in unprovoked PE-group than in provoked (1.85% vs 8.52%, p = .042).

Unprovoked PE occurs at a younger age, more frequently in males. It is characterized by the following significant variables: higher Wells score, lower PESI score, lower CRP, higher thrombotic burden and lower one-month mortality rate, compared to provoked PE.