This study was designed to evaluate whether the absence of coronary calcium could rule out 50% coronary stenosis or the need for revascularization.

The latest American Heart Association guidelines suggest that a calcium score (CS) of zero might exclude the need for coronary angiography among symptomatic patients.

A substudy was made of the CORE64 (Coronary Evaluation Using Multi-Detector Spiral Computed Tomography Angiography Using 64 Detectors) multicenter trial comparing the diagnostic performance of 64-detector computed tomography to conventional angiography. Patients clinically referred for conventional angiography were asked to undergo a CS scan up to 30 days before.

In all, 291 patients were included, of whom 214 (73%) were male, and the mean age was 59.3 ± 10.0 years. A total of 14 (5%) patients had low, 218 (75%) had intermediate, and 59 (20%) had high pre-test probability of obstructive coronary artery disease. The overall prevalence of 50% stenosis was 56%. A total of 72 patients had CS = 0, among whom 14 (19%) had at least 1 50% stenosis. The overall sensitivity for CS = 0 to predict the absence of 50% stenosis was 45%, specificity was 91%, negative predictive value was 68%, and positive predictive value was 81%. Additionally, revascularization was performed in 9 (12.5%) CS = 0 patients within 30 days of the CS. From a total of 383 vessels without any coronary calcification, 47 (12%) presented with 50% stenosis; and from a total of 64 totally occluded vessels, 13 (20%) had no calcium.

The absence of coronary calcification does not exclude obstructive stenosis or the need for revascularization among patients with high enough suspicion of coronary artery disease to be referred for coronary angiography, in contrast with the published recommendations. Total coronary occlusion frequently occurs in the absence of any detectable calcification. (Coronary Evaluation Using Multi-Detector Spiral Computed Tomography Angiography Using 64 Detectors [CORE-64]; NCT00738218)

J Am Coll Cardiol, 2010; 55:627.