Perspective:

This very interesting study has several important take home messages: 1) Although ischemia is uncommon in patients with zero CAC, the rates are not negligible with a pooled average of 8.5% of subjects with zero CAC having ischemia, ranging up to 50% in one study. This suggests that in appropriate patients with typical symptoms, a zero calcium score is insufficient to rule out ischemia. 2) Calcium was highly prevalent in both ischemic and nonischemic scans. This suggests that prevention medications are likely to be important in many subjects with nonischemic stress tests. 3) Approximately one in four patients with extensive CAC (≥400) had an ischemic stress test, supporting recommendations to offer stress testing to these patients. This study was challenging in that many of the underlying studies which were analyzed used different categorization schemes for CAC. Furthermore, one could ask the question whether ischemia is the only relevant outcome. Patients who had silent, completed myocardial infarctions could have CAC and fixed perfusion abnormalities (i.e., no inducible ischemic defects). These patients could warrant further investigation and would likely benefit from secondary prevention therapies.