Contrast enhanced electron beam computed tomography to analyse the coronary arteries in patients after acute myocardial infarction

Abstract

Objective: To evaluate the accuracy of contrast enhanced electron beam computed tomography (EBCT) after acute myocardial infarction in determining patency of the infarct related artery and detecting high grade stenoses and occlusions in the coronary vessels.

Design: Case study using blinded comparison with invasive coronary angiography.

Patients: 36 patients (mean age 53 years) 4-70 days after acute myocardial infarction.

Interventions: The patients were studied by EBCT and invasive coronary angiography. For EBCT, 50 axial images of the heart (3 mm slice thickness) were acquired. They were triggered by the ECG during breath holding, after intravenous injection of contrast agent. The original images, surface reconstructions, and maximum intensity projections were evaluated for the presence of high grade stenoses and occlusions of the coronary arteries.

Main outcome measures: EBCT results were compared with invasive coronary angiography.

Results: Of a total of 144 coronary arteries (left main, left anterior descending, left circumflex, and right coronary artery in 36 patients), 29 (20%) were unevaluable by EBCT. In the remaining arteries, 33 of 36 high grade lesions were correctly detected (92% sensitivity). Specificity was also 92% (73/79). Patency of the infarct related artery was correctly detected in 15 of 16 cases (94%). Five of the 14 occluded infarct related arteries (35%) were mistaken as stenotic but patent, and six could not be assessed.

Conclusions: EBCT is very accurate in detecting significant coronary artery lesions in patients after acute myocardial infarction, but differentiation between occluded and patent infarct related arteries is currently unreliable.

Figure 1

Contrast enhanced EBCT study in a 36 year old male patient after anterior myocardial infarction, without significant stenoses on invasive coronary angiography. (A) Contrast enhanced tomogram at the level of the aortic root shows the left main and left anterior descending coronary artery (arrow). (B) Three dimensional reconstruction of the heart showing left anterior descending coronary artery without significant stenosis. The surface reconstruction is thresholded to show only the contrast enhanced lumen of the coronary arteries. (C) Maximum intensity projection of the coronary arteries showing left anterior descending coronary artery without stenosis. (D, E) Invasive coronary angiography: absence of significant stenoses in the left anterior descending coronary artery after anterior myocardial infarction.

Figure 2

Thirty nine year old male patient after anterolateral myocardial infarction. (A, B) Surface reconstruction shows a high grade stenosis in a large diagonal branch (arrow). (C) Maximum intensity projection of the coronary arteries (arrow: stenosis of diagonal branch). (D) Invasive coronary angiography confirms high grade stenosis of the diagonal branch (arrow).

Figure 3

Sixty four year old male patient after posterior myocardial infarction. (A) Shaded surface display: occlusion of the right coronary artery (arrow). (B) Invasive coronary angiography confirms occlusion of the right coronary artery (arrow).

Figure 4

Thirty six year old male patient after anterior myocardial infarction. (A) On EBCT, a long subtotal stenosis of the left anterior descending coronary artery is diagnosed. (B) Invasive coronary angiography shows complete occlusion of the left anterior descending coronary artery (large arrow) with filling of the distal vessel segments via collaterals (small arrows).