Prevalence of risk factors, coronary and systemic atherosclerosis in abdominal aortic aneurysm: comparison with high cardiovascular risk population.

Background: Abdominal aortic aneurysm (AAA) is considered a manifestation of atherosclerosis, however there are epidemiologic, biochemical, and structural differences between occlusive atherosclerosis and AAA. The pathogenesis of AAA involves several factors, first of all destruction of collagen and elastin in the aortic wall. Classical risk factors may influence the evolution and development of AAA, though no consistent association has been found. Aims of the study were to evaluate associations between risk factors and to establish the prevalence of carotid, peripheral vascular and coronary atherosclerosis in patients with AAA.

Methods: We studied 98 patients with AAA (Group 1) awaiting surgery compared with high cardiovascular risk population having two or more risk factors (n=82 Group 2). We evaluated traditional risk factors and we studied by eco-doppler and echocardiography the presence of carotid peripheral and coronaric atherosclerosis in two groups.

Results: We found a higher incidence of AAA in males (p < 0.01). The prevalence of infrarenal AAA was significantly higher than suprarenal AAA (81 vs. 17 p < 0.001). No differences in total cholesterol (199 +/- 20 vs. 197 +/- 25 mg/dl), low-density lipoprotein (142 +/- 16 vs. 140 +/- 18 mg/dl), triglycerides (138 +/- 45 vs. 144 +/- 56 mg/dl), glycemia (119 +/- 15 vs. 122 +/- 20 mg/dl), and fibrinogen (388 +/- 154 vs. 362 +/- 92 mg/dl) were found between groups. We demonstrated significant differences for cigarette smoking (p < 0.002), systolic and diastolic blood pressure (150 +/- 15 vs. 143 +/- 14 mmHg and 88 +/- 6 vs. 85 +/- 7 mmHg, p < 0.0001 and p < 0.05, respectively) and high sensititivity C reactive protein (2.8 +/- 1.3 vs. 1.3 +/- 0.7 mg/dl, p < 0.001). High-density lipoprotein (HDL) cholesterol levels were significant greater in Group 1 than Group 2 (p < 0.003). Subgroups of patients with AAA and luminal thrombus showed higher fibrinogen levels (564 +/- 235 vs. 341 +/- 83 mg/dl, p < 0.001) and lower HDL than in controls (46.6 +/- 6.5 vs. 52.1 +/- 7.8 mg/dl, p < 0.01). We did not find any difference in body mass index, or prevalence of coronary and peripheral atherosclerosis between groups. Conversely, we found higher prevalence of carotid atherosclerosis in Group 2 (9% vs. 25%, p < 0.004).

Conclusion: Our AAA patients had fewer and different risk factors respect to patients with atherosclerosis. Only elevated blood pressure, C reactive protein, and smoking showed a significant association with AAA. Atherosclerosis in other arterial districts did not differ respect to subjects with high cardiovascular risk. Our results confirm the hypothesis that AAA and atherosclerosis are two different pathological entities with different risk profiles.