Citing the systemic nature of atherosclerosis, the authors of this paper studied the association between extracranial carotid atherosclerosis features and prior ischemic stroke (IS) and coronary heart disease (CHD).
Patients were selected from the Rotterdam Study. Participants with at least 2.5mm of carotid intima media thickness (IMT) were eligible for this study. Of 3,795 eligible participants, 1,982 underwent MRI of bilateral carotid arteries. MRI was performed on 1.5-Tesla scanners with a carotid artery protocol. All plaques of at least 2mm of thickness were assessed for intraplaque hemorrhage (IPH), lipid core, and calcification. Additionally, wall thickness and degree of stenosis were determined. Participants’ history was queried for prior IS and CHD (non-fatal MI or myocardial revascularization). Covariates were age, sex, smoking status, lipid measurements, BMI, diabetes, and hypertension.
Binomial logistic regression was used to determine the association between individual plaque characteristics and history of IS and CHD. Men and women were examined separately.
One thousand seven hundred thirty-one participants were ultimately included. The mean age was 73 years, and 55% were male. A majority of patients had a history of smoking. IS and CHD were much more common in men, as were vascular risk factors. The mean carotid wall thickness was 3.6mm, and the mean degree of stenosis was 13%. IPH was present in 35%, lipid core in 41%, and calcification in 82%. In terms of outcomes, 105 had a history of IS, and 199 had a history of CHD.
In the overall population, in multivariate analysis, only degree of stenosis was associated with IS. For men, stenosis and IPH were associated with IS. In both the overall population and when stratified by sex, only carotid stenosis was associated with CHD.
The key finding is that whereas plaque thickness or stenosis were associated with both IS and CHD, IPH was only associated with IS (in men). The dependence on prevalence data and the lack of clinical data (e.g. stroke laterality or mechanism) limit the conclusions that can be drawn from this study. However, this work may foreshadow and stimulate prospective, mechanistically enlightening studies that capitalize on the granularity of MRI data.