Abstract P032: Increased Abdominal Aortic Diameters on Multidetector CT Scan Are Independent Predictors of Incident Adverse Cardiovascular Events

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Abstract

Introduction: Adverse aortic remodeling, such as dilation, is cross-sectionally associated with multiple cardiovascular disease (CVD) risk factors. We sought to determine whether increased, though not necessarily aneurysmal, abdominal aortic diameters augment prediction of incident adverse CVD events above standard CVD risk factors in a community-dwelling cohort. This may be useful since the aorta is often incidentally visualized on computed tomography (CT) body scans performed for indications other than CVD risk stratification.

Methods: Participants (N=3318, aged 50±10y, 51% M) from the Framingham Offspring and Third Generation Cohorts who were free of clinical CVD, had complete risk factor profiles (collected at the adjacent cycle exams), and had non-contrast, abdominal multidetector CT scans (MDCT) during 2002-2005 were included in this study. Anteroposterior (AP) and left-right (LR) diameters were measured in the infrarenal (IAA) and lower abdominal (LAA) aorta. The IAA was measured at 5 cm above the aortoiliac bifurcation and the LAA was measured at one slice level (2.5mm) above the bifurcation of the abdominal aorta into the common iliac arteries. For each segment, the greater of AP and LR diameters was used in the analyses. Adverse events comprised CVD death, myocardial infarction, coronary insufficiency, index admission for heart failure, and stroke. For each aortic segment, hazard of an adverse event for enlarged IAA or LAA diameter (enlarged was defined as ≥ upper 90th percentile diameter for age, sex and BSA) was determined using multivariable (MV) adjusted Cox proportional hazards models.

Results: Over a mean 8.8±2.0y of follow-up, there were 149 incident adverse CVD events. In multivariable models adjusted for traditional CVD risk factors, enlarged IAA was associated with greater hazard of an adverse CVD event (HR 1.62; 95% CI 1.07-2.46; p=0.022). However, the association of enlarged LAA with adverse CVD events was borderline (HR 1.56; 95% CI 0.99-2.46; p=0.054).

Conclusion: Among community-dwelling adults initially free of clinical CVD, enlarged infrarenal abdominal (IAA) aortic diameter, as determined from noncontrast MDCT scans, augments prediction of incident adverse CVD events above traditional risk factors alone.

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