CT coronary calcification: What does a score of "0" mean?

Calcium score (CS) is a useful tool in evaluating the risk of cardiovascular events in asymptomatic patients. The absence of detectable calcification determines excellent cardiovascular prognosis, with event rates lower than that of negative stress studies, probably due to the latter's inability to detect nonobstructive coronary artery disease (CAD). There are few primary prevention medications that would be cost-effective in such a low-risk patient population. The interval for retesting patients with zero CS is still open for debate but it should not be in less than 4 to 5 years. CS should not be used to rule out obstructive CAD in symptomatic patients, as its correlation with coronary stenosis is poor and obstructive CAD is commonly found among symptomatic zero CS patients. Most studies have found very low specificity values for CS to detect obstructive CAD in symptomatic patients, meaning it has limited ability to detect the true negative cases (ie, zero CS without obstructive CAD).