Dual Source CT after left main coronary artery stenting in a patient with arrhythmias

Case history
• 63 year old male patient
• Known chronic occlusion of LAD
• Previous bypass surgery
• Now experienced an ACS
• High grade stenosis of left main coronary artery was found

Percutaneous coronary intervention (PCI) and stent placement (5.0/12 mm) of the left main coronary artery was performed to restore blood flow to the left circumflex coronary artery and an intermediate branch [Fig. 1].

Several days after stent placement, the patient experienced non-typical chest pain at rest and a Dual Source CT scan was performed to investigate stent patency. During the DSCT scan, the patient developed arrhythmias (supraventricular ectopic beats). Image reconstruction was performed in systole (300 ms after R-wave), and half-scan reconstruction (heart rate independent 83 ms temporal resolution) was used.

[1A] Angiography of the right coronary artery (arrow).	[1B] Angiography of the intact internal mammary artery graft (large arrow) to the left anterior descending coronary artery (small arrows).
[1C] High-grade stenosis of left main coronary artery (arrow).	[1D] After PCI and stent placement into the left main coronary artery, there is no residual stenosis in the left main coronary artery (large arrow). Diffuse disease of the left circumflex coronary artery remains (small arrows; arrowhead = intermediate branch).

[2] ECG trace during DSCT data acquisition. Heart rate is highly irregular due to supraventricular ectopic beats, rapidly changing between 48 and 90 bpm.

Diagnosis
In the systolic reconstructions, the heart, coronary arteries, and the bypass graft were visualized free of motion artifacts [Fig. 3-5], in spite of the presence of arrhythmias throughout data acquisition. The left main coronary artery stent was depicted in axial and frontal multiplanar reconstructions and could clearly be demonstrated to be free of acute thrombotic occlusion or restenosis [Fig. 3]. In addition, reconstructions of the arterial bypass graft and of the right coronary artery showed both vessels free of significant stenosis. Diffuse disease had remained in the left circumflex coronary artery after the percutaneous intervention, and these stenoses were also demonstrated by DSCT, without change to the angiographic finding [Fig. 4 and 5]. Thus, a repeat invasive coronary angiogram was not necessary.

Comments
In spite of arrhythmias during scanning, Dual Source CT was able to rule out the presence of in-stent narrowing or occlusion of the newly implanted left main coronary artery stent. In addition, patency of the internal mammary artery bypass graft and absence of new stenosis in the right coronary artery could be demonstrated.

[3] Reconstruction of the left main coronary artery stent in a frontal [3A] and axial plane [3B] and in a curved multiplanar reconstruction that shows the stent and the left circumflex coronary artery [3C]; (large arrow: patent stent, small arrows: diffuse disease in left circumflex coronary artery, compare to Fig. [1D]).

[4] Curved multiplanar reconstruction of the right coronary artery [4A] (arrow, no significant stenosis) and of the left main and left anterior descending coronary artery [4B] (known to be occluded; arrows =LAD, arrowhead =distal segment of IMA bypass graft and anastmosis to LAD).
[5A, 5B] 3-dimensional reconstruction of the heart and coronary arteries. The patent internal mammary artery graft to the left anterior descending coronary artery can clearly be appreciated.

Authors: Stephan Achenbach, Ulrike Ropers, Dieter Ropers, Katharina Anders, Axel Küttner, Willi Kalender, Werner Bautz, Werner G. Daniel

See corresponding protocol: Dual Source CT after left main coronary artery stenting in a patient with arrhythmias