High coronary calcium scores up the risk of coronary events

Adding coronary calcium to the assessment of conventional cardiovascular risk factors leads to substantial improvement in cardiovascular risk classification of asymptomatic men and women, according to a study presented at the RSNA on Wednesday afternoon.

Strong associations were found between the extent of coronary calcium and the risk of coronary events, with hazard ratios up to 9.6 in men and up to 21.6 in women, said presenter of the study Dr. Rozemarijn Vliegenthart Proenca, a radiology resident at the University Medical Center Groningen in the Netherlands.

More than 2000 asymptomatic patients were assessed by electron-beam tomography to determine amounts of coronary calcium in this prospective population-based study. When coronary calcium was added to the Framingham risk model, reclassification was most substantial in subjects initially classified as intermediate risk.

In men, 65% of those originally classified as at an intermediate risk were reclassified when coronary calcium was added to the risk model. More than a third (38%) moved to the low-risk category, and 27% moved to the high-risk category.

In women, 66% of those originally classified as at an intermediate risk were reclassified when coronary calcium was added to the risk model. Nearly half (45%) moved to the low-risk category, and 21% moved to the high-risk category.

“The reclassification was based on the actual events,” Proenca said. “So the observed risks in the different categories were repopulated based on our risk model, our prediction model, and based on the actual events occurring in the risk categories.”

Other studies have just shown that a high calcium score can affect risk stratification in a population, but were not based on actual events, she said.