WASHINGTON — Coronary artery calcification and common carotid wall thickness are similarly predictive of total cardiovascular disease events in elderly community-dwelling adults, Anne B. Newman, M.D., reported at a conference on cardiovascular disease epidemiology and prevention sponsored by the American Heart Association.
Several noninvasive methods that document the extent of vascular disease have been shown to predict cardiovascular events, but these methods have not previously been directly compared in the same population, said Dr. Newman of the division of geriatric medicine at the University of Pittsburgh.
As part of the National Heart, Lung, and Blood Institute's Cardiovascular Health Study, 559 participants with a mean age of 80 years underwent both carotid ultrasound and coronary artery calcium (CAC) scans; 40% of the participants were male and 22% were black. At the time of the scans, clinical cardiovascular disease (CVD) was present in 33%.
A total of 112 events, including 23 myocardial infarctions, 24 cases of angina, 15 strokes, and 13 cases of heart failure, occurred over 4.4 years of follow-up. Death due to CVD occurred in 27 subjects, she reported at the meeting, also sponsored by the National Heart, Lung, and Blood Institute.
Total cardiovascular event rates per 100 person-years increased linearly by quartiles of CAC scores: 2.81 for those with scores of 0–56, 5.08 for scores of 57–332, 6.63 for scores of 333–916, and 7.37 for scores greater than 917. Compared with those in the lowest CAC quartile, the hazard ratio for each subsequent quartile—adjusted for age, sex, and prevalent CVD—were 1.76, 2.28, and 2.31, with the upper two reaching statistical significance.
Common carotid artery (CCA) wall thickness was similarly predictive, with event rates ranging from 2.89 per 100 person-years for those with CCA wall thickness of less than 0.95 mm up to 9.30 for those with CCA thickness of 1.23–3.14 mm. The hazard ratios for the upper three quartiles compared with the lowest were 1.43, 1.86, and 2.94. Again, the upper two were significant, Dr. Newman said.
Similar predictive ability of both CAC and common carotid artery wall thickness were seen when the analysis was repeated for incident cardiovascular disease event rates among the 373 subjects who did not already have CVD at baseline, she said.
Although the internal common carotid artery (ICA) wall thickness was more highly correlated with the coronary artery calcium score than was the common carotid artery wall thickness, the relative risks between ICA wall thickness and mortality were not as strong as for the other two measures. With ICA, even the 1.50 hazard ratio for total cardiovascular disease events between the lowest quartile (less than 1.01 mm) and the highest (2.13–6.15 mm) was not significant.