Proximal aortic distensibility is an independent predictor of all-cause mortality and incident CV events: the MESA study

Abstract

Background: The predictive value of ascending aortic distensibility (AAD) for mortality and hard cardiovascular disease (CVD) events has not been fully established.

Objectives: This study sought to assess the utility of AAD to predict mortality and incident CVD events beyond conventional risk factors in MESA (Multi-Ethnic Study of Atherosclerosis).

Methods: AAD was measured with magnetic resonance imaging at baseline in 3,675 MESA participants free of overt CVD. Cox proportional hazards regression was used to evaluate risk of death, heart failure (HF), and incident CVD in relation to AAD, CVD risk factors, indexes of subclinical atherosclerosis, and Framingham risk score.

Results: There were 246 deaths, 171 hard CVD events (myocardial infarction, resuscitated cardiac arrest, stroke and CV death), and 88 HF events over a median 8.5-year follow-up. Decreased AAD was associated with increased all-cause mortality with a hazard ratio (HR) for the first versus fifth quintile of AAD of 2.7 (p = 0.008) independent of age, sex, ethnicity, other CVD risk factors, and indexes of subclinical atherosclerosis. Overall, patients with the lowest AAD had an independent 2-fold higher risk of hard CVD events. Decreased AAD was associated with CV events in low to intermediate- CVD risk individuals with an HR for the first quintile of AAD of 5.3 (p = 0.03) as well as with incident HF but not after full adjustment.

Conclusions: Decreased proximal aorta distensibility significantly predicted all-cause mortality and hard CV events among individuals without overt CVD. AAD may help refine risk stratification, especially among asymptomatic, low- to intermediate-risk individuals.

Keywords: aortic stiffness; cardiovascular risk; magnetic resonance imaging; mortality.

FIGURE 1. Principle of local aortic stiffness: Distensibility of the Ascending Aorta

During systole, the ascending aorta stores most of the left ventricular stroke volume, which is released downstream during diastole thereby transforming a pulsatile flow into a steadier flow. This cushioning effect allows minimizing energy expenditure. The relative change in aortic lumen area divided by pulse pressure defines distensibility (A). Comparative illustration of preserved (left) and altered (right) distensibility of the ascending aorta (B) and corresponding cross-sectional area to cardiac cycle time curves for preserved (blue) and altered (red) aortic distensibility (C).

FIGURE 2. Measurement of Aortic Distensibility in MRI

Magnetic resonance imaging (MRI) shows 3-dimensional reconstruction of the thoracic aorta with transverse aortic dynamic acquisition plane (red) (A). Result of the semi-automated segmentation of the ascending aorta (green contour) (B). Resulting cross- sectional area to cardiac cycle time curve (C).

FIGURE 3. CENTRAL ILLUSTRATION Cumulative Event-Free Probabilities for Survival and Survival Free of CVD

The cumulative event-free probabilities for survival (A) and survival free of incident hard cardiovascular disease (CVD) (B) display similar patterns according to extreme quintiles of ascending aorta distensibility (AAD).