Research letterCarotid extra-medial thickness does not predict adverse cardiovascular outcomes in high-risk adults
Introduction
The arterial adventitia has been implicated in the vascular remodelling process of atherosclerosis. Carotid extra-medial thickness (EMT) is a reproducible non-invasive measure of elastic artery adventitial thickness obtained by high-resolution ultrasound [1], [2]. Carotid EMT is correlated with both intima-media thickness (IMT) and arterial stiffness from the same arterial segment, yet is associated with cardiovascular risk factors including BMI and diabetes independent of atherosclerotic involvement of the arterial intima and media [1], [3], [4], [5].
The prognostic significance of carotid EMT, however, has not yet been examined. Thus, we sought to determine whether carotid EMT is associated with risk of incident cardiovascular events, in adults at risk of coronary artery disease (CAD).
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Study design and participants
We retrospectively measured carotid EMT from ultrasound images collected as part of a study that previously demonstrated an association of carotid IMT with cardiovascular events in adults at risk of coronary artery disease (CAD) [6]. Consecutive patients deemed at risk of CAD were prospectively enrolled from cardiology and renal outpatient clinics from December 1998 to July 2002, for risk evaluation and subsequent follow-up, as described previously [6]. Selection criteria included known or
Clinical characteristics
From the 444 patients in whom we assessed common carotid artery vascular structure, 437 had complete follow-up outcome analyses, and of these 348 (80%) had measurable carotid EMT (0.91 mm; SD 0.17 mm). Participant characteristics did not differ between those included in this analysis, and those without measurable carotid EMT (data not shown).
Outcomes
The median duration of follow-up was 24 months (interquartile range 12–36 months). Of the 57 events observed, there were 37 deaths (21 cardiovascular), 9
Discussion
This study aimed to investigate the potential value of carotid EMT in predicting cardiovascular events and found that carotid EMT, unlike carotid IMT measured from the same arterial segment, was not significantly associated with cardiovascular events or survival in adults at high risk of CAD.
The prognostic value of carotid IMT as a predictor of cardiovascular events has previously been reported in this cohort and others [6], [10]. Due to the comprehensive ultrasound scanning protocol used in
Disclosure of interest
M.R.S. is supported by a Future Leader fellowship from the National Heart Foundation of Australia (#100419).
T.Y. Cai, C. Magnussen, B. Haluska, D.W. Johnson, P.M. Mottram, N. Isbel, D.S. Celermajer, T.H. Marwick declare that they have no competing interest.
Acknowledgement
None.
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