Several studies have demonstrated an association between high calcium scores and heart disease and the potential benefits of CT CAC in determining an individual's risk of cardiac conditions. As a result, the American Heart Association (AHA) and the American College of Cardiology (ACC) have framed their most recent guidelines to support the use of CT CAC testing for adults at risk of developing atherosclerotic heart disease.
Still, the U.S. Preventive Services Task Force (USPSTF) has maintained the position that more evidence demonstrating the benefits of nontraditional risk factors, including CT CAC, is required before such factors can be recommended for routine clinical use.
Thus, the current study seeks to provide further backing for the use of CT CAC in identifying people with the greatest risk of developing cardiovascular disease who might benefit from more aggressive preventive therapy, first author Dr. Michael Miedema of the Minneapolis Heart Institute Foundation and colleagues noted.
The researchers focused their investigation on 22,346 adults between the ages of 30 and 49 who underwent a CT CAC exam as part of the U.S. CAC Consortium study and tracked the health status of the individuals for an average of 12.7 years. Approximately 34% of the middle-aged adults had some amount of calcium on their baseline CT CAC scan, with 7.2% having CT CAC scores of at least 100 Agatston units (AU).
At the end of the roughly 12-year period, the group found that 67.5% of all deaths related to coronary artery disease occurred in individuals with a positive baseline CT CAC score. The team also found that individuals with a calcium score greater than 100 AU were significantly more likely than those with a score of 0 to be affected by the five traditional risk factors: hypertension, hyperlipidemia, smoking history, family history of coronary artery disease, and diabetes.
Overall, the researchers noted a considerably higher rate of mortality due to coronary artery disease, cardiovascular disease, and all causes among individuals with a CT CAC score of at least 1 AU, compared with individuals who had a score of 0. These mortality rates were even higher for those with a score greater than 100 AU.
The differences between the positive scores and a score of 0 were statistically significant (p < 0.001).
|Effect of varying CT CAC scores on mortality rates for middle-aged adults
|Rate per 1,000 person-years
||CT CAC score = 0
||CT CAC score = 1 to 100
||CT CAC score > 100
|Coronary artery disease-related death
|Cardiovascular disease-related death
After adjusting for traditional risk factors, the researchers calculated that individuals with a CT CAC score exceeding 100 AU had a fivefold increase in risk of mortality from coronary artery disease and a threefold increase from cardiovascular disease, compared with those who had a score of 0.
"The high prevalence of premature coronary atherosclerosis in this sample of younger adults highlights the need to increase focus on the importance of adopting healthy lifestyle behaviors early in life," the authors wrote. "In addition, these findings suggest that CAC testing could potentially be considered for further risk stratification in select young adults with elevated cardiovascular risk."
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