The absence of coronary calcification does not exclude obstructive coronary artery disease or the need for revascularization in patients referred for conventional coronary angiography

Abstract

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

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

Methods: 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.

Results: 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 >or=50% stenosis was 56%. A total of 72 patients had CS = 0, among whom 14 (19%) had at least 1 >or=50% stenosis. The overall sensitivity for CS = 0 to predict the absence of >or=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 >or=50% stenosis; and from a total of 64 totally occluded vessels, 13 (20%) had no calcium.

Conclusions: 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).

Figure 1. Distribution of Patients on the Basis of CS and Coronary Stenosis

CS = calcium score; pts = patients.

Figure 2. Individual Values of CS and Maximum Coronary Stenosis in Subjects

Linear regression plot showing the poor correlation between the maximum degree of coronary stenosis by conventional coronary angiogram (CCA) and the calcium score (CS) in a patient.

Figure 3. Prevalence of Obstructive CAD and Need for Clinically Indicated Revascularization Among Patients in Different CS Categories

As the CS increases, the prevalence of obstructive coronary artery disease (CAD) and revascularization also increase (p < 0.001 for all trends). Note that the group of 0 CS patients has high prevalence of obstructive CAD and revascularization. The blue bars indicate CCA ≥50%; the red bars indicate CCA ≥70%; and the green bars indicate revascularization. Abbreviations as in Figure 2.

Figure 4. A Patient From Our Study

Example of an outpatient 53-year-old man with 0 calcium score and severe stenosis on the midportion of the left descending coronary (arrows), as can be seen on the conventional angiogram (A), on the multiplanar reformatted image (B), and on the 3-dimensional volume rendered image (C) from coronary computed tomography angiogram. The stenosis also extends to a diagonal branch, as can be seen in A and C.