Abstract 184: The 8.7-year Follow-up For Prediction Of Stroke By Enlargement Of Carotid Arteries In a General Urban Cohort: The Suita Study
Authors: Kokubo Yoshihiro , Koga Masatoshi , Watanabe Makoto , Toyoda Kazunori , Nagatsuka Kazuyuki , Miyamoto Yoshihiro 
Published: July 2021

Introduction:
Carotid intima-media thickness (IMT) has been increasingly used as a subclinical marker for stroke and ischemic heart disease (IHD). However, no study has examined the association between enlargement of carotid arteries and the incidence of stroke in general populations. We assessed the hypothesis that carotid artery enlargement was a predictor for stroke events in a general urban Japanese population.

Methods:
We studied 5,330 Japanese individuals (mean age 55.3 years, without stroke or IHD) who completed a baseline survey and carotid ultrasonography in the Suita Study, and were then followed for 8.7 years on average. Carotid atherosclerosis was evaluated by high-resolution ultrasonography (7.5MHz transducer) with atherosclerotic indexes of IMT in the common carotid artery (CCA), carotid artery bulbs (Bulbs), and internal and external carotid arteries (ICA and ECA, respectively). The CCA-int and the CCA-adv diameters were defined as the means of the minimal lumen-intima diameters and the maximal media-adventitia diameters for both sides of the CCA, respectively, at the beginning points of dilation of the Bulbs in the diastolic phase. The ICA and the ECA diameters were defined as the means of the minimal intima-lumen diameters for both sides of the ICA and the ECA at the points where the ICA and the ECA were divided from the Bulbs in the diastolic phase, respectively. The risks of stroke across quartiles according to carotid arteries diameters were compared by the use of multivariable-adjusted Cox proportional-hazards models.

Results:
In 46,553 person-years of follow-up, we documented 124 cerebral infarctions, 49 hemorrhagic strokes, 12 unclassified strokes, and 125 IHD events. The multivariable-adjusted hazard ratios (HRs; 95% confidence intervals [CIs]) in the highest quartile of the CCA-int diameter (>6.65 mm) for all strokes, ischemic and hemorrhagic strokes were 2.62 (1.54 to 4.47), 2.27 (1.17 to 4.41), and 4.38 (1.51 to 12.68), respectively, compared with the lowest quartile of the CCA-int diameter (<5.7 mm). The multivariable-adjusted HRs (95% CIs) for all strokes, ischemic and hemorrhagic strokes, lacunar, and atherothrombotic infarctions were 1.61 (1.32 to 1.96), 1.51 (1.19 to 1.92), 2.12 (1.41 to 3.19), 1.31 (0.86 to 2.00), and 2.53 (1.45 to 4.41) in 1-mm increments of the CCA-int diameter, respectively. Those HRs (95% CIs) were 1.24 (1.05 to 1.47), 1.18 (0.97-1.45), 1.49 (1.07 to 2.07), 0.87 (0.62 to 1.23), and 1.97 (1.19 to 3.24) in 1-mm increments of the ICA diameter, respectively. The risks of strokes for the CCA-adv diameter were similar to those for CCA-int. No association of the ECA diameter with stroke was observed.

Conclusions:
Enlargement of both the CCA and the ICA is an independent risk factor for stroke and its subtypes in the general population. Carotid artery enlargement may be a good predictor for stroke in general populations.