Calciumscore verhoogt nauwkeurigheid voorspellen CADNieuws - 22 okt. 2010
CAC score improves CAD prediction accuracy
Researchers say that coronary artery calcification (CAC) scoring improves the accuracy of predicting the risk for coronary artery disease (CAD) event, compared with traditional risk factors.
Raimund Erbel (University Duisburg-Essen, Hufelandstrasse, Germany) and colleagues say that CAC scoring particularly improves identification of a high proportion of intermediate-risk individuals, a finding that may have important implications in reducing the number of coronary events in the general population.
The researchers measured CAC scores and traditional CAD risk factors, such as age, gender, blood pressure, and cholesterol levels, in 4129 asymptomatic individuals (aged 45-75 years) from the Heinz Nixdorf Recall (HNR) study.
Participants were categorized into low (less than 10% or 6% in 10 years), intermediate (10-20% or 6-20% in 10 years), and high (greater than 20% in 10 years) risk according to the Framingham Risk Score (FRS) and National Cholesterol Education Panel Adult Treatment Panel (NCEP-ATP) III guidelines. The rate of reclassification according to CAC score was then assessed.
During the 5-year follow up, the participants were asked to complete annual postal questionnaires and attend a medical examination to assess their morbidity status. After 5 years, 93 coronary deaths and nonfatal myocardial infarctions had occurred.
The team found that patients with high CAC scores had a significantly increased risk for such hard events, with relative risks increased nearly five- and 10-fold in patients with a CAC score of 100-399 or greater than 400, respectively, compared with lower scores.
In comparison, patients with a CAC score of 0 had a very good prognosis, with a hard event rate of just 0.16% per year. CAC testing also improved risk prediction of hard events, particularly among patients in the intermediate-risk (10-20%) FRS group. Patients in this group with a high CAC score had a similar rate of hard events as that of patients in the high-risk FRS group, at 8.7% and 5.4%, respectively.
The results were similar when a 6-20% threshold for intermediate risk was used and when NCEP-ATP III criteria were used instead of FRS.
Moreover, reclassifying patients in the intermediate risk-group as low risk if they had a CAC below 100 and as high risk if they had a CAC of at least 400 improved risk prediction by 21.7% and 30.6%, respectively.
Writing in the Journal of the American College of Cardiology, Erbel and colleagues say: "CAC scoring results in a high reclassification rate in the intermediate-risk cohort, demonstrating the benefit of imaging of subclinical coronary atherosclerosis."
However, they also state that "physicians have to be aware that the proposed risk stratification algorithms are not perfect, as events do rarely occur in those who are classified as low risk even when CAC scores are low."