Effect of heart rate and coronary calcification on the diagnostic accuracy of the dual-source CT coronary angiography in patients with suspected coronary artery disease

Abstract

Objective: To evaluate the diagnostic accuracy of a dual-source computed tomography (DSCT) coronary angiography, with a particular focus on the effect of heart rate and calcifications.

Materials and methods: One hundred and nine patients with suspected coronary disease were divided into 2 groups according to a mean heart rate (< 70 bpm and >or= 70 bpm) and into 3 groups according to the mean Agatston calcium scores (<or= 100, 101-400, and > 400). Next, the effect of heart rate and calcification on the accuracy of coronary artery stenosis detection was analyzed by using an invasive coronary angiography as a reference standard. Coronary segments of less than 1.5 mm in diameter in an American Heart Association (AHA) 15-segment model were independently assessed.

Results: The mean heart rate during the scan was 71.8 bpm, whereas the mean Agatston score was 226.5. Of the 1,588 segments examined, 1,533 (97%) were assessable. A total of 17 patients had calcium scores above 400 Agatston U, whereas 50 had heart rates >or= 70 bpm. Overall the sensitivity, specificity, positive predictive values (PPV) and negative predictive values (NPV) for significant stenoses were: 95%, 91%, 65%, and 99% (by segment), respectively and 97%, 90%, 81%, and 91% (by artery), respectively (n = 475). Heart rate showed no significant impact on lesion detection; however, vessel calcification did show a significant impact on accuracy of assessment for coronary segments. The specificity, PPV and accuracy were 96%, 80%, and 96% (by segment), respectively for an Agatston score less than 100% and 99%, 96% and 98% (by artery). For an Agatston score of greater to or equal to 400 the specificity, PPV and accuracy were reduced to 79%, 55%, and 83% (by segment), respectively and to 79%, 69%, and 85% (by artery), respectively.

Conclusion: The DSCT provides a high rate of accuracy for the detection of significant coronary artery disease, even in patients with high heart rates and evidence of coronary calcification. However, patients with severe coronary calcification (> 400 U) remain a challenge to diagnose.

Keywords: Coronary angiography; Coronary artery disease; Dual-source computed tomography.

Fig. 1

Dual-source CT coronary angiography in 50-year-old man with suspected coronary artery disease (mean heart rate 88 bpm). Curved-planar maximum-intensity projections (A) and three-dimensional volume rendering technique reconstructions (B) of left anterior descending artery both demonstrate significant artery stenosis of mid segment (arrow). Patient has one-vessel disease. Invasive coronary angiography (C) confirms significant stenosis of mid segment of right coronary artery (arrow).

Fig. 2

Dual-source CT coronary angiography in 50-year-old man with suspected coronary artery disease (Agatston score 823). Curved-planar maximum-intensity projections (A) of left anterior descending artery demonstrate significant stenosis of proximal and mid segment (arrow). However, invasive coronary angiography (B) in right anterior oblique cranial view shows mild to moderate degree of lumen reduction (< 50%) in proximal and mid segment (arrow) of left anterior descending artery, resulting in false positive diagnosis in dual-source CT coronary angiography. Patient has three-vessel disease and shows diffused calcification in left circumflex artery and right coronary artery (figure not shown).