Effect of False Lumen Status on Systemic Inflammatory Response Induced by Acute Aortic Dissection

Introduction: Acute aortic dissection (AAD) frequently induces a systemic inflammatory reaction. However, the influence of dissection morphology on immune response remains to be elucidated. Hypothesis: False lumen (FL) status influences peripheral blood cytokine expression in patients with AAD. Methods: Serum concentrations of 29 cytokines were measured on admission (within 48 hours of symptom onset) in 44 patients with AAD. None were suffering shock or aortic rupture and none had an autoimmune or hematologic disease. The 44 patients were divided into 2 groups based on FL patency: those with a thrombosed FL (Group T [n=21]: median age, 76 years) and those with a partially thrombosed or fully patent FL (Group P [n=23]: median age, 61 years). Stanford classes did not differ between these groups (Group T: type A, n=7; type B, n=14 vs. Group P: type A, n=14; type B, n=9) (p=0.068). Laboratory values, including cytokine concentrations, were compared between these groups and a control group (Group C—patients with a non-ruptured atherosclerotic thoracic aortic aneurysm—n=20]: median age, 75 years) by Mann-Whitney test, with multiple comparisons subjected to Bonferroni correction. Results: Leukocyte counts (x10e3/μL) were increased in both groups (Group T: 9.5 [7.7, 11.7]; Group P: 14.0 [10.4, 18.0] vs. Group C: 5.8 [5.0. 7.1]) (both p<0.001), but CRP concentrations (mg/dL) were not (0.51 [0.15, 3.3], p=0.077 and 0.38 [0.10, 2.7], p=0.165 vs. 0.2 [0.1, 0.21]). D-dimer concentrations (μg/mL) were increased in Group P (28.8 [8.6, 108], p<0.001) but not in Group T (2.9 [1.5, 5.3], p=0.87) (vs. Group C: 2.5 [1.4, 4.9]). Seventeen cytokines [IFNγ, IL-2, IL-4, IL-17α, TNFα, etc.] did not differ significantly between the 2 AAD groups; 12 did differ significantly. The differentially expressed cytokines fell into 3 hierarchical clusters: cluster A (increased expression in both groups [G-CSF, IL-6, IL-10, IL-15]), cluster B (increased expression only in Group P [GM-CSF, IL-1Ra, IL-1b, IL-8, IL-12p70, IP-10], and cluster C (increased expression only in Group T [IL-5, VEGF]). Conclusions: A robust inflammatory response occurs regardless of FL status, but the response is somewhat attenuated in patients with a thrombosed FL vs. those with a patent FL.