Clinical implications of the coronary artery calcium score in Japanese patients

Coronary artery calcification (CAC) is a well-established surrogate marker of the total burden of coronary atherosclerosis. The CAC score, as measured on coronary computed tomography (CT), is associated with the prevalence of coronary artery disease (CAD) as well as cardiovascular morbidity and mortality. The CAC score is used to reclassify coronary risks in asymptomatic individuals with intermediate risks. However, there are few clinical data regarding the usefulness of the CAC score for identifying high-risk Japanese patients. In this review article, we describe our previous studies of the prognostic value of the CAC score in patients with proven or suspected CAD. In addition, we reanalyzed our previous data for 723 patients with suspected CAD and found both all-cause and cardiovascular disease mortality to be significantly higher among the patients with a CAC score of ≥100 than among those with a CAC score of ＜100. Several studies from Japan have also shown that the CAC score is associated with the prevalence of obstructive CAD, as demonstrated on invasive coronary angiography or stress myocardial perfusion imaging. Furthermore, the CAC score provides useful information for performing coronary CT angiography, as asymptomatic patients without CAC are expected to have favorable outcomes. In contrast, the diagnostic accuracy is decreased in patients with a high CAC score (＞400 or 600). In conclusion, the CAC score may have useful clinical applications in symptomatic and asymptomatic Japanese individuals. However, further studies are required to evaluate the prognostic value of this parameter for predicting cardiovascular morbidity and mortality in population-based analyses of asymptomatic Japanese subjects.