Significant coronary calcification detected using contrast-enhanced computed tomography: Is it an indication for further investigation?

BACKGROUND: Evaluate the significance of coronary arteries calcifications detected using contrast-enhanced chest computed tomography (CECCT) scans. METHODS: A total of 145 patients who underwent both CECCT and gated stress myocardial perfusion imaging (MPI) within 2 weeks were included. The chest CT scans were reviewed for the presence of coronary artery calcium (CAC) by 2 experienced blinded readers. The degree of calcifications seen in any visualized area of the major coronary arteries was graded on a scale of 1 to 3 (1 when 0 to 4 small scattered plaques were seen, 2 when 5 or more scattered plaques were seen, and 3 when diffuse contiguous calcification were seen). The grade of CAC was correlated with the presence of MPI abnormalities. Additionally, the locations of the MPI abnormality was correlated with the CAC grade in the culprit coronary artery. RESULTS: Of 580 major coronary arteries evaluated, 79% had grade 1 CAC, 10% had grade 2, 11% had grade 3, and 1% were inevaluable. Of the 145 patients, 33 (23%) had abnormal MPI results. Twenty-three of the patients with abnormal MPI results (70%) had more than 4 calcified plaques (CAC grade of 2 or 3) in one or more of their coronary arteries, whereas 41 of 122 patients with normal MPI results (37%) had similar CAC grades (P = 0.001). Seventeen of the 33 patients (52%) who had MPI defects also had significant CAC in the culprit coronary artery, 7 patients (21%) had significant CAC in a different coronary artery from the MPI defect territory, 8 patients (24%) had no significant CAC visualized, and in 1 patient a pacemaker wire interfered with CAC grading in the culprit coronary artery (RCA). The sensitivity, specificity, the positive, and negative predictive values of grade 2 or 3 CAC for an abnormal MPI results were 70%, 63%, 36%, and 88%, respectively. When a subgroup of patients above 60 years old with grade 3 CAC was reanalyzed, the sensitivity, specificity, the positive, and negative predictive values for an abnormal MPI results were 69%, 73%, 41%, and 90%, respectively. CONCLUSION: Multiple diffuse CAC as detected during the interpretation of CECCT scans in combination with advanced age is a significant finding that warrants further investigation for functionally significant CAD.