[Effect of coronary calcification on diagnostic accuracy of the 64 row computed tomography coronary angiography]

Coronary artery calcium is known to complicate the evaluation of stenoses using computer tomography (CT). The aim of this study was to analyze the effect of coronary calcification on the diagnostic accuracy of CT coronary angiography in an Icelandic population.

The study was a retrospective analysis of 417 consecutive subjects that underwent CT coronary angiography and subsequent conventional coronary angiography within 6 months. Subjects were divided based on total Agatston score: 0, 0.1-10, 10.1-100, 100.1-400, 400.1-750 and >750. Sensitivity, specificity, positive and negative predictive values were calculated for ≥50% stenoses diagnosed with the CT, using the conventional coronary angiography as a reference. Correlation between Agatston score and ≥50% stenoses was calculated.

A total of 1668 coronary artery segments in 417 individuals were evaluated (68.6% men, mean age 60.2 ± 8.9). The total mean Agatston score was 420 (range from 0-4275). CT detected >50% stenoses with a sensitivity of 70.1%, specificity of 79.9% and positive and negative predictive values of 55.4% and 88.2%, respectively. The negative predictive value was 93.0% for Agatston score zero but 78.3% for Agatston score ˃750. An Agatston score threshold of 363 predicted ≥50% coronary stenoses with 49.6% sensitivity.

Diagnostic accuracy is moderate with good negtive predictive value and specificity. Although coronary calcification reduces diagnostic accuracy, negative predictive value is only mildly affected for Agatston score as high as 400. Agatston score is not a good predictor of ≥50% coronary artery stenoses. No particular Agatston score cut-off level was identified to indicate whether CT angiography was useless or not.