Impact of sex and age on carotid plaque instability in asymptomatic patients-results from the Munich Vascular Biobank.

BACKGROUND: It is still a controversial issue whether carotid endarterectomy (CEA) for asymptomatic carotid stenosis is superior to best medical treatment. The aim of this study was therefore to analyze the impact of sex and age on carotid plaque instability in asymptomatic patients undergoing CEA. PATIENTS AND METHODS: Atherosclerotic plaques from 465 asymptomatic patients with high-grade carotid artery stenosis (2004 - 2013) at the Munich Vascular Biobank were analyzed. Ascertainment of lesion stability/instability was performed on formalin-fixed paraffin-embedded tissue samples using hematoxylin-eosin and elastic van Gieson staining. Unstable plaques were considered lesions with a fibrous cap < 200 µm overlaying lipid-rich atheroma. RESULTS: The average age of the patients was 69.3 ± 8.2 years. Independent of age, asymptomatic men had in total more frequently unstable plaques in contrast to women (41 % versus 52%, p = 0.042). No differences were found in plaque instability between age-related quartiles (< 65, 65- 69, 70 - 74, > 74 years) for female sex (p = 0.422). In men, a continuous increase in plaque instability with age was observed, without achieving statistical significance (p = 0.125). The greatest differences between male and female sex were found in the last quartile (> 74 years), without achieving statistical significance (p = 0.053). The chance of unstable carotid plaques in men was significantly higher than in women (OR = 1.562, p = 0.040). The probability of age-associated quartiles related to the first quartile demonstrated significant increase in plaque instability in the group of 65- to 69-year-old patients (OR 1.867, p = 0.024) and for patients older than 74 years (OR 1.740, p = 0.040). CONCLUSIONS: Asymptomatic men had in total more frequently unstable plaques in contrast to women. Thus, male sex seems to be an additional risk factor for ischemic stroke.