Predictive value of coronary calcifications for future cardiac events in asymptomatic patients: underestimation of risk in asymptomatic smokers

Coronary calcification (CAC) is an established marker for coronary atherosclerosis and has a highly specific predictive value for cardiovascular events. This study aimed to determine the predictive value in the specific group of asymptomatic smokers in comparison to non-smokers. We included 1432 asymptomatic individuals (575 women, 857 men, age 59.2 ± 7.7 years.) in this study. Coronary calcification was calculated by multi-slice computed tomography following a standardized protocol including calcium score (CS). Coronary risk factors were determined at inclusion. After mean observation time of 76.3 ± 8.5 months the patients were contacted and evaluated for cardiovascular events (myocardial infarction, cardiac death and revascularisation). Mean CS was 231 ± 175 in smokers and 239 ± 188 in non-smokers. Cardiovascular events were found in 14.9% of our patients and there were significantly more events in smokers (119 events, 8.3%) than in non-smokers (94 events, 6.6%, p = 0.001). CS > 400 showed a hazard ratio for future cardiac events of 5.1 (95% CI 4.3–7.6) in smokers and 4.4 (95% CI 3.4–6.2) in non-smokers, p = 0.01. Also in smokers determination of CAC is a valuable predictor of future cardiovascular events. In our study smokers showed throughout all score groups a significantly higher risk compared to non-smokers with equal CS. Therefore, CS may underestimate the risk for future cardiac events in smokers compared to non-smokers.