Atrial fibrillation is related to lower incidence of deep venous thrombosis in patients with pulmonary embolism

Background: Atrial fibrillation (AF) is an established risk factor of left atrial thrombosis and systemic embolism. Traditionally pulmonary embolism (PE) is a recognized complication of deep vein thrombosis (DVT). However, whether AF is responsible for right atrial thrombosis and leads to PE has not been examined. Methods: We retrospectively analyzed medical records of patients with confirmed diagnosis of PE with AF (study group) from 2002-2015. Patients with PE without AF, matched by age and sex, served as controls (control group). The CHA₂DS₂-VASc and CHADS₂ scores were classified into two categories, lowintermediate ( < 2 points) and high-risk (≥2 points). Results: A total of 330 patients (110 in study group and 220 in control group). The study group had significantly lower incidence of newly diagnosed DVT (21% vs. 44%, P < 0.001), previous history of DVT (6% vs. 17%, P=0.006) and recent surgery or trauma (10% vs. 23%, P=0.004) compared to the control group. When stratified by the CHADS₂ score, 49 patients (44.5%) were considered low-intermediate risk. This proportion significantly differed when stratified using CHA₂DS₂-VASc, in which 13 patients (13.6%) were considered low-intermediate risk, P<0.001. Conclusions: The incidence of DVT was much lower in the study group, suggesting the possibility of clots originated from the right heart that may increase the risk of PE. The CHA₂DS₂-VASc scoring system might be more sensitive for prediction and stratification of the PE in AF patients than the CHADS₂ score.