There are millions of lung CT scans done annually in the United States for the primary evaluation of lung diseases in smokers. Currently, these scans are not used to evaluate for heart disease, despite the fact that smoking predisposes patients to both heart (number one cause of death in the United States) and chronic obstructive pulmonary disease (COPD, the number 3 cause of death in the United States). These scans contain potentially important information related to heart disease, with evidence of calcification of the heart (coronary) and aorta readily visible. These calcifications, when obtained on a dedicated heart CT scan, have been shown to represent blockages in the coronary arteries, and are routinely used to determine that patients are at increased risk of heart disease. However, most of the time, these calcifications are ignored on lung CT scans, as the exact clinical significance and prevalence is unknown. By using a large ongoing trial of smokers who are already undergoing CT scans of the chest, we can demonstrate a relationship between tobacco use, COPD and coronary plaque buildup (calcification), without requiring more testing. Using the same CT scan obtained to evaluate for lung disease, we can simultaneously evaluate for the presence of early heart disease, without a requirement for additional testing, radiation or injections to the patient.
This study proposed to take previously obtained scans and evaluate them specifically for heart disease, in the form of calcified plaque in the coronary arteries (coronary artery calcium) and aorta (thoracic aortic calcium). Both of these measures have been validated in numerous studies, but almost all previous studies have obtained the scans using a dedicated cardiac CT scan, and not attempting to garner this information from a scan obtained for other purposes. The technical differences in obtaining the scan data makes this process different, and establishing standard values for this population using this technique is required before these measures can be applied to all scans obtained. The validation becomes even more critical, as there will be differences due to motion artifacts in the current CT scans of the lung, and careful evaluation for these calcifications will be required. The CT reading center at Los Angeles Biomedical Research institute is the most experienced reading center for coronary and thoracic calcium, having performed these measures for over 15 major NIH studies to date. We have the experience to accurately measure this plaque and incorporate the data into useful clinical information.
This study aims to evaluate 10,500 existing CT scans for measures of coronary and thoracic calcium on the well established COPD-Gene® study. This existing cohort already has extensive measures of lung function and structure, and we propose to add measures of heart disease. If this study is successful, it will help validate the utility of measuring coronary artery calcium and thoracic aortic calcium in patients already undergoing CT scanning for evaluation of lung disease. This can leverage, at virtually no cost, the scan obtained and garner information on two diseases at once. In an age of increasing health care costs, this technique has great promise to provide needed information on the number one cause of death in this population, at no additional costs. We propose to study this large well-established existing cohort of patients (n=10,500 participants), we will simultaneously be able to provide specific information for both males and female smokers, and both African-American and white groups. It has previously been demonstrated that women suffer heart disease, on average, 10 years later than men, however the potential interaction of smoking and lung disease on this process has not been well evaluated.
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