Catheterization and Cardiovascular Interventions 65:34–36 (2005)
Case Reports Multislice CT to Evaluate Coronary Stent Patency: A Case Report Kean H. Soon,1* Kevin W. Bell,2 and Yean L. Lim,1
PhD
This is a case report on the ability of 16-slice computed tomography in assessing the patency of coronary stent and diagnosing an asymptomatic stenotic lesion with soft plaque morphology. These findings were confirmed with a selective coronary angiography. Identification of lesion morphology facilitated our decision on prophylactic and direct stenting to the lesion. ' 2005 Wiley-Liss, Inc. Key words: noninvasive coronary angiography; prophylactic stenting
A 54-year-old male ex-CEO was followed up for his coronary artery disease. He gave history of ventricular fibrillation (VF) posttreadmill stress test 6 years ago. He subsequently had bare metal stents inserted into his left anterior descending artery (LAD) and distal right coronary artery (RCA). He had been well ever since with no symptoms of exertional angina or dyspnoea. His risk factors for ischemic heart disease (IHD) included family history of IHD and hypercholesterolemia. He was a nonsmoker and free of diabetes. His regular medications included aspirin 100 mg daily, ramipril 10 mg daily, and atorvastatin 40 mg daily. He was eager to have a test (other than selective coronary angiography) to ascertain the patency of his stents. He was investigated with an exercise stress nuclear perfusion study and a noninvasive CT coronary angiography. His stress nuclear perfusion study was normal. His CT coronary angiography was performed with a GE LightSpeed-16 slice CT scanner set at 120 kV, 440 mA, pitch of 0.325, and collimation of 0.6 mm (spatial resolution of 0.6 mm). He was given a single dose of 50 mg oral metoprolol 1 hr prior to the CT coronary angiography to achieve a heart rate of 58 beats/min. Contrary to the findings of the nuclear perfusion study, his CT coronary angiography revealed a 70–80% stenotic lesion with a soft plaque and ulcerative appearance proximal to his RCA stent (Fig. 1). Otherwise, his coronary stents in RCA and LAD were clearly visible and patent on multislice computed tomography (MSCT) coronary angiography (Fig. 2). A lesion at least 50% stenosis was also noted distal to the LAD stent (Fig. 2). In view of past history of VF arrest following an exercise stress test, it was decided ' 2005 Wiley-Liss, Inc.
that he should have a selective coronary angiography with the view of stenting the lesion proximal to the RCA stent. His subsequent selective coronary angiography confirmed the finding of a significant stenotic lesion proximal to RCA stent (Fig. 3); both of his stents in LAD and RCA were confirmed patent (Figs. 3 and 4). The lesion distal to the LAD stent was not as stenotic as seen on CT angiography. In view of the soft plaque appearance of the lesion in mid RCA on MSCT coronary angiography with no significant calcification, prophylactic stenting with a sirolimus-coated stent was performed without balloon predilation following his diagnostic coronary angiography. Concerns about the safety and cost of selective coronary angiography have driven the development of noninvasive coronary imaging modalities. Among all, multidetector-row CT (MDCT) or MSCT scanner has shown a tremendous potential. Equipped with 16 rows of detectors, the latest 16-slice CT scanner is capable of imaging coronary artery with submillimeter spatial 1
Centre for Cardiovascular Therapeutics, Western Hospital, Footscray, Victoria, Australia 2 Department of Radiology, Western Hospital, Footscray, Victoria, Australia *Correspondence to: Kean H. Soon, Centre for Cardiovascular Therapeutics, Western Hospital, Footscray, VIC 3011, Australia. E-mail:
[email protected] Received 25 June 2004; Revision accepted 26 January 2005 DOI 10.1002/ccd.20336 Published online 24 March 2005 in Wiley InterScience (www.interscience. wiley.com).
Multislice CT
Fig. 1. A multiplanar reconstruction (MPR) image of MSCT coronary angiography reveals a significant stenotic lesion in RCA with a soft plaque character and a patent stent in RCA. Step-wise artifacts are due to atrial contraction during cardiac diastole. RV, right ventricle; LV, left ventricle.
Fig. 2. An MPR image of MSCT coronary angiography shows a patent stent in LAD.
resolution within a single breath hold [1]. Numerous studies have been performed to assess the sensitivity and specificity of four-slice CT coronary angiography. Early studies with four-slice CT scanner in the diagnosis of coronary artery disease revealed a wide range of
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Fig. 3. A selective coronary angiography in the left anterior oblique (LAO) view confirms the patency of stent in distal RCA and a tight stenosis proximal to the stent.
Fig. 4. A selective coronary angiography confirms the findings of MSCT coronary angiography of a patent stent in LAD artery. A lesion distal to LAD stent is not as stenotic as seen on MSCT coronary angiography.
sensitivity and specificity of 78–92% and 68–95%, respectively [2–4]. More recently, studies with 16-slice CT coronary angiography show a more realistic accuracy with sensitivity and specificity of 92–95% and
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86–93%, respectively [1,5]. However, the ability of MSCT in the assessment of stent patency has not been adequately assessed. The major hindrance of stent assessment with MSCT has always been stent artifacts, which appear as high-density blooming effects of stent struts impairing visualization of stent lumen [6]. This case report illustrates the ability of the latest 16-slice CT in the evaluation of stent patency. Direct visualization of stent lumen with MSCT coronary angiography as illustrated in this case is a much more confirmative noninvasive investigation than treadmill stress test, stress nuclear perfusion study, or stress echo study. Other than being noninvasive, MSCT coronary angiography also has the advantage of assessing both the lumen and the wall of coronary artery, i.e., the plaque morphology. Schroder et al. [7] have shown that MSCT coronary angiography is capable of differentiating plaque morphology into soft (lipid-rich) and hard plaque (calcified) quite accurately when compared with intravascular ultrasound. In support of these findings, Schoenhagen et al. [8] also reported MSCT coronary angiography has the accuracy comparable with intracoronary ultrasound in identifying plaque presence, calcification, distribution, and positive remodeling (correlation of 0.9). In essence, MSCT coronary angiography has the potential of functioning as intravascular ultrasound without its invasive nature. As illustrated in this case, upon confirming the stenosis on selective coronary angiography, knowledge of the soft plaque morphology from MSCT coronary angiography may help to facilitate the decision of direct stenting. On the other hand, if there is heavy calcification discovered on MSCT coronary angiography but not well appreciated on fluoroscopy, atherectomy prior to stenting would be preferable. Vigorous predilation to the heavily calcified lesion may increase the risks of dissection. There are several limitations of CT coronary angiography. Due to its limited temporal resolution, a heart rate of > 65/min during CT scan may result in poor vessel visibility [9]. Atrial contraction during diastolic phase may result in step-wise artifacts (as illustrated in Fig. 1) affecting the visualization of right coronary artery. Heavy calcification in the vessel wall may hinder assessment of lumen patency due to calcium blooming effects. As illustrated in this case and other published studies, CT coronary angiography has the tendency of overestimating the degree of stenosis and resulting in a false positive finding and limited positive predictive value [1].
In the near future, we will see the emergence of 64- or 128-slice CT scanners. With improved spatial and temporal resolutions in these newer generations of MSCT, further improvement in the diagnostic accuracy of CT coronary angiography is expected. It is foreseeable that CT coronary angiography will play an important role in the assessment of stent patency, plaque characterization, and planning the strategy for percutaneous coronary intervention. REFERENCES 1. Nieman K, Cademartiri F, Lemos PA, Raaijmakers R, Pattynama PM, de Feyter PJ. Reliable noninvasive coronary angiography with fast submillimeter multislice spiral computed tomography. Circulation 2002;106:2051–2054. 2. Achenbach S, Giesler T, Ropers D, Ulzheimer S, Derlien H, Schulte C, Wenkel E, Moshage W, Bautz W, Daniel WG, et al. Detection of coronary artery stenoses by contrast-enhanced, retrospectively electrocardiographically-gated, multislice spiral computed tomography. Circulation 2001;103:2535–2538. 3. Knez A, Becker CR, Leber A, Ohnesorge B, Becker A, White C, Haberl R, Reiser MF, Steinbeck G. Usefulness of multislice spiral computed tomography angiography for determination of coronary artery stenoses. Am J Cardiol 2001;88:1191–1194. 4. Nieman K, Rensing BJ, van Geuns RJ, Munne A, Ligthart J, Pattynama P, Krestin G, Serruys P, de Feyter P. Usefulness of multislice computed tomography for detecting obstructive coronary artery disease. Am J Cardiol 2002;89:913–918. 5. Ropers D, Baum U, Pohle K, Anders K, Ulzheimer S, Ohnesorge B, Schlundt C, Bautz W, Daniel WG, Achenbach S. Detection of coronary artery stenoses with thin-slice multi-detector row spiral computed tomography and multiplanar reconstruction. Circulation 2003;107:664–666. 6. Nieman K, Cademartiri F, Raaijmakers R, Pattynama P, de Feyter P. Noninvasive angiographic evaluation of coronary stents with multi-slice spiral computed tomography. Herz 2003; 28:136–142. 7. Schroeder S, Kopp AF, Baumbach A, Meisner C, Kuettner A, Georg C, Ohnesorge B, Herdeg C, Clausen CD, Karsch KR. Noninvasive detection and evaluation of atherosclerotic coronary plaques with multislice computed tomography. J Am Coll Cardiol 2001;37:1430–1435. 8. Schoenhagen P, Tuzcu EM, Stillman AE, Moliterno DJ, Halliburton SS, Kuzmiak SA, Kasper JM, Magyar WA, Lieber ML, Nissen SE, et al. Non-invasive assessment of plaque morphology and remodeling in mildly stenotic coronary segments: comparison of 16-slice computed tomography and intravascular ultrasound. Coron Art Dis 2003;14:459–462. 9. Schroeder S, Kopp AF, Kuettner A, Burgstahler C, Herdeg C, Heuschmid M, Baumbach A, Claussen CD, Karsch KR, Seipel L. Influence of heart rate on vessel visibility in noninvasive coronary angiography using new multislice computed tomography: experience in 94 patients. Clin Imaging 2002;26: 106–111.
