Patients with isolated pulmonary embolism in comparison to those with deep venous thrombosis. Differences in characteristics and clinical evolution

Background: Patients with acute pulmonary embolism (PE) often have leg deep vein thrombosis (DVT); sometimes, however, a DVT is not detected (isolated PE, I-PE). We aimed at assessing the proportion of patients with I-PE, and their characteristics and clinical evolution compared to those with DVT with/without PE (DVT/PE). Methods: Among 3573 patients included in the START2-Register for a venous thromboembolic event, 2880 (80.6%) had DVT/PE, the remaining I-PE (19.4%). Results: Patients with I-PE were older [(>= 75 years, OR 1.4 (95%CI 1.13-1.69)], and more frequently females [OR 1.4 (1.19-1.67)]. Young females (aged <= 50 years) with an index event occurring during hormonal contraception (HC), were more prevalent in I-PE [OR 1.96 (1.26-3.03)]. At multivariate analysis, age > 75 years, female sex, heart failure, cancer and use of HC were risk factors significantly associated with I-PE, whereas thrombophilic alterations were associated with DVT/PE. During a follow-up of 4504 years (during anticoagulation), the rate of bleeding events was 1.1% patient/years and 1.0% patient/years in I-PE and DVT/PE, respectively. Venous thromboembolic events were equally prevalent in DVT/PE or I-PE (1.94% vs 0.86%, ns), whereas arterial complications were more prevalent in the latter group (1.01% vs 0.28%, p = 0.008). Conclusion: I-PE and DVT/PE have important differences. Older age, female sex, heart failure and cancer, were risk factors for I-PE; thrombophilic alterations were associated with DVT/PE. HC use was more frequent in the I-PE group. The prevalence of arterial complications was higher in patients with I-PE. Further studies, specifically designed on this issue, are warranted.