Left iliac vein involvement is a protective factor against symptomatic pulmonary embolism in lower left extremity deep vein thrombosis

Abstract

ObjectiveLeft iliac vein compression is associated with left iliac vein thrombosis (IVT), potentially limiting the migration of the thrombus from this stenotic segment to the pulmonary arteries. We sought to investigate the differences in clinical characteristics and risk factors of symptomatic pulmonary embolism (SPE) in patients with deep vein thrombosis (DVT) in different limbs and anatomical locations. MethodsA retrospective analysis was conducted of 1476 patients with acute unilateral lower extremity DVT. Differences of clinical characteristics and risk factors between left-sided and right-sided DVT, IVT, and non-IVT, cases with SPE and cases without SPE were compared. Risk factors for SPE were investigated using logistic regression analysis. ResultsSPE was more common in patients with right-sided DVT than patients with left-sided DVT (13.8% vs 7.0%; P < .001). SPE incidence in left IVT (5.4%) was lower than that in left non-IVT, right IVT, and right non-IVT (12.8%, 10.1%, 16.6%, respectively; P < .001). There was no difference in SPE incidence among patients with left non-IVT, right IVT and right non-IVT (P > .05). In patients with left-sided DVT, male sex was associated with an increased odds of SPE (odds ratio [OR], 1.77; 95% confidence interval [CI], 1.10-2.85; P = .02). IVT, surgery, and immobilization were associated with a decreased odds of SPE (OR, 0.46 [95% CI, 0.28-0.76; P < .01]; OR, 0.55 [95% CI, 0.32-0.95; P = .03]; and OR, 0.53 [95% CI, 0.32-0.86; P = .01]). In patients with right-sided DVT, provoked DVT was associated with a decreased odds of SPE (OR, 0.50; 95% CI, 0.27-0.93; P = .03). ConclusionsLeft IVT is associated with a lower SPE incidence than right-sided DVT. Left IVT and may be a relative protective factor against SPE.