Prevalence of Carotid Plaque in a 63- to 65-Year-Old Norwegian Cohort From the General Population: The ACE (Akershus Cardiac Examination) 1950 Study

Abstract

Background: New data on extracranial carotid atherosclerosis are needed, as improved ultrasound techniques may detect more atherosclerosis, the definition of plaque has changed over the years, and better cardiovascular risk control in the population may have changed patterns of carotid arterial wall disease and actual prevalence of established cardiovascular disease. We investigated the prevalence of atherosclerotic carotid plaques and carotid intima-media thickness (cIMT) and their relation to cardiovascular risk factors in a middle-aged cohort from the general population.

Methods and results: We performed carotid ultrasound in 3683 participants who were born in 1950 and included in a population-based Norwegian study. Carotid plaque and cIMT were assessed according to the Mannheim Carotid Intima-Media Thickness and Plaque Consensus, and a carotid plaque score was used to calculate atherosclerotic burden. The participants were aged 63 to 65 years, and 49% were women. The prevalence of established cardiovascular disease was low (10%), but 62% had hypertension, 53% had hypercholesterolemia, 11% had diabetes mellitus, and 23% were obese. Mean cIMT was 0.73±0.11 mm, and atherosclerotic carotid plaques were present in 87% of the participants (median plaque score: 2; interquartile range: 3). Most of the cardiovascular risk factors, with the exception of diabetes mellitus, obesity and waist-hip ratio, were independently associated with the plaque score. In contrast, only sex, hypertension, obesity, current smoking, and cerebrovascular disease were associated with cIMT.

Conclusions: We found very high prevalence of carotid plaque in this middle-aged population, and our data support a greater association between cardiovascular risk factors and plaque burden, compared with cIMT.

Clinical trial registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT01555411.

Keywords: atherosclerosis; cardiovascular disease; carotid artery; carotid ultrasound.

Figure 1

Carotid intima–media thickness (cIMT). The cIMT was measured in B‐mode, longitudinal view, using a semiautomated IMT package for the Vivid E9 system. The measurements were conducted over a minimum 10‐mm length, at the far wall in the common carotid artery (CC), at least 5 mm proximal of the bifurcation in an area with clearly defined lumen–intima and in a region free of plaque. The mean average cIMT was used (0.55 mm in this example). IMT, indicates intima–media thickness.

Figure 2

Plaque formation located in the right common carotid (CC) artery. For calculation of the carotid plaque burden, the carotid artery was divided in 4 segments (common carotid artery, bifurcation, and internal and external carotid artery), and plaques were assessed in each segment. The largest plaque from every segment was measured. Plaque diameters ≥1.5, ≥2.5, and ≥3.5 mm were given 1, 2, and 3 points, respectively, with a segment score of 2 (diameter of the largest plaque: 3.1 mm) for the right common carotid artery in this participant. Finally, the scores from all segments were summarized into a total plaque burden score ranging from 0 to 24 points.

Figure 3

Plaque score distribution.

Figure 4

Flowchart of the ACE (Akershus Cardiac Examination) 1950 study population.