Relation between quantitative coronary CTA and myocardial ischemia by adenosine stress myocardial CT perfusion

Abstract

Background: Coronary-computed tomography angiography (CTA) has limited accuracy to predict myocardial ischemia. Besides luminal area stenosis, other coronary plaque morphology and composition parameters may help to assess ischemia. With the integration of coronary CTA and adenosine stress CT myocardial perfusion (CTP), reliable information regarding coronary anatomy and function can be derived in one procedure. This analysis aimed to investigate the association between coronary stenosis severity, plaque composition and morphology and the presence of ischemia measured with adenosine stress myocardial CTP.

Methods and results: 84 patients (age, 62 ± 10 years; 48% men) who underwent sequential coronary CTA and adenosine stress myocardial CT perfusion were analyzed. Automated quantification was performed in all coronary lesions (quantitative CTA). Downstream myocardial ischemia was assessed by visual analysis of the rest and stress CTP images and defined as a summed difference score of ≥1. One or more coronary plaques were present in 146 coronary arteries of which 31 (21%) were ischemia-related. Of the lesions with a stenosis percentage <50%, 50%-70%, and >70%, respectively, 9% (6/67), 18% (9/51), and 57% (16/28) demonstrated downstream ischemia. Furthermore, mean plaque burden, plaque volume, lesion length, maximal plaque thickness, and dense calcium volume were significantly higher in ischemia-related lesions, but only stenosis severity (%) (OR 1.06; 95% CI 1.02-1.10; P = .006) and lesion length (mm) (OR 1.26; 95% CI 1.02-1.55; P = .029) were independent correlates.

Conclusions: Increasing stenosis percentage by quantitative CTA is positively correlated to myocardial ischemia measured with adenosine stress myocardial CTP. However, stenosis percentage remains a moderate determinant. Lumen area stenosis and lesion length were independently associated with ischemia, adjusted for coronary plaque volume, mean plaque burden, maximal lesion thickness, and dense calcium volume.

Keywords: Coronary artery disease; imaging; myocardial CT perfusion; myocardial ischemia; quantitative coronary CTA.

Figure 1

(A) Quantitative CTA and adenosine stress CTP of an ischemic lesion. Example of a 58-year-old female patient with a lesion in the first diagonal branch and corresponding myocardial ischemia. A Automated quantitative CTA of the artery was performed. The blue lines were set proximal and distal to the lesion. The green and red lines represent non-diseased coronary artery segments proximal and distal to the lesion. The yellow and orange lines represent the reference markers for, respectively, the lumen and vessel wall. The vertical yellow line is placed at the site of maximal stenosis percentage: 76.6%. Furthermore, mean plaque burden was 79.9%; plaque volume: 129.3 mm³; lesion length: 19.0 mm; maximal plaque thickness: 2.6 mm; dense calcium volume: 36.6 mm³. B Longitudinal lumen and vessel wall contours. C Transverse lumen and vessel wall contours at the site of maximal stenosis percentage. D 3D fusion of the coronary CTA and myocardial hypo-perfusion during adenosine stress (orange, red). A stenosis in the first diagonal branch (arrow) is depicted with corresponding myocardial ischemia. E Rest CTP study showing normal myocardial enhancement. F Adenosine stress myocardial CTP showing a small anterolateral subendocardial perfusion defect (arrow). (B) Quantitative CTA and adenosine stress CTP of a non-ischemic lesion. Same data reconstructions as shown in (A). A non-ischemic coronary lesion in the proximal LCX is depicted. Maximal stenosis percentage was: 69.1%. Mean plaque burden was: 67.2%; plaque volume: 27.1 mm³; lesion length: 3.5 mm; maximal plaque thickness: 1.8 mm; dense calcium volume: 9.4 mm³. Despite the high stenosis percentage, lesion length, maximal plaque thickness, and dense calcium volume were relatively low, resulting in normal myocardial enhancement on adenosine stress

Figure 2

(A) Vessel-based analysis relating stenosis percentage to myocardial ischemia. (B) Patient-based analysis relating stenosis percentage to myocardial ischemia. (C) Extent of CAD related to myocardial ischemia. CAD, Coronary artery disease; VD, vessel with ≥50% stenosis