Epidemiology of Coronary Calcification in the Elderly

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Recent studies indicate that coronary artery calcium is a strong predictor of coronary heart disease events in middle- aged men and women. We examined the extent and predictors of coronary artery calcium and its relationship to other non- invasive measures of atherosclerosis in 614 (89 percent) of the surviving cohort from the Pittsburgh center of the Cardiovascular Health Study (CHS). These individuals were ages 67-99 (mean 80). Key findings have been reported and include: 1) Coronary artery calcium scores were strongly age related, yet the range of scores was quite broad. Ten percent had scores of zero. 2) Other non- invasive vascular tests missed many of those with high coronary calcium scores. 3) Other than age, gender and race, traditional risk factors were relatively weak predictors of calcification. We now propose to follow these individuals to determine whether coronary artery calcification predicts cardiovascular disease and mortality in old age, and whether this is independent of other non-invasive measures of disease and traditional risk factors. The alternative hypothesis is that the risk is attenuated in old age, as it may represent stable plaque that is less prone to occlusion or rupture. The CHS is ending the ascertainment of outcomes at the end of 2001, necessitating additional funding for local follow-up of this cohort. In addition to monitoring cardiovascular events, we will evaluate the functional significance of the extent of calcification by an exercise test and will assess progression after 4 years by repeating the EBT scan, and determine the rate of new calcification in those with scores of zero at baseline. Such individuals with no calcium might be regarded as "immune from coronary artery disease." The specific aims are: 1) To determine whether the extent of coronary artery calcium is an independent predictor of total and incident myocardial infarction and total CVD morbidity and mortality in older adults. 2) To determine the functional significance of coronary artery calcification in about 312 of these older adults without clinical cardiovascular disease. 3) To determine the rate of progression over 4 years in coronary artery calcium score in an estimated 424 survivors and to determine if those with zero (n=47) develop any calcification. This study can determine the risk of cardiovascular disease events in relationship to coronary artery calcium in older adults in a time-efficient and cost- effective manner that capitalizes on the rich CHS database. This is the largest population study of coronary artery calcium in this older age group, and can rapidly produce definitive data to determine the potential for benefit of screening older adults for coronary artery calcium.