Effort angina in a patient with advanced coronary artery disease. Role played by coronary angiography, Ivus and cardiac CT: case report
© Zardi et al; licensee BioMed Central Ltd. 2008
Received: 11 August 2008
Accepted: 24 September 2008
Published: 24 September 2008
Coronary angiography is considered to be the gold standard technique for assessing the severity of obstructive luminal narrowing; however, in a few circumstances it may be misleading. In these cases, cardiac computed tomography (CT) and intravascular ultrasound (IVUS) may help to give a correct interpretation.
In this report, we describe the case of a 62-year-old man whose effort angina was first evaluated with coronary angiography, but whose severe stenosis of the right coronary artery was only observed on cardiac CT and IVUS. This additional diagnosis promptly resulted in a therapeutic approach with percutaneous transluminal coronary angioplasty (PTCA).
Advanced coronary artery disease (CAD) may be caused by multiple stenotic lesions in which plaque remodelling and thrombus play an important role. Since the 60's, coronary angiography has been proven to be the gold standard invasive method for assessing CAD and providing information about the silhouette of the coronary artery lumen; however, much of the information about the coronary artery wall and plaque composition cannot be captured using this technique [1, 2]. Recently, new cardiac imaging techniques such as intravascular ultrasound (IVUS), which can be used to depict coronary arteries and assess atherosclerotic plaques, and cardiac computed tomography (CT), which can be used to estimate the degree of coronary artery calcification, have become available. IVUS, because of its ability to better characterize atherosclerotic plaques, promises to become a powerful complementary tool to coronary angiography. In addition, cardiac CT, which can be used to reveal stenotic coronary vessels and study bypass grafts, may be used as a non-invasive method .
We report a case of a 62-year-old man in which the diagnosis of a critical stenotic lesion was reached only after performing the three imaging techniques mentioned above (coronary angiography, cardiac CT and IVUS).
The patient was discharged on an optimized medical therapy regimen of aspirin (100 mg), atenolol (50 mg b.i.d.), clopidogrel (75 mg) for 12 months and statin (20 mg).
A follow-up scintigraphy 6 months later revealed absence of ischemia.
This case provides a good illustration of the ineffectiveness of coronary angiography for depicting the wall structure of coronary arteries. In contrast, cardiac CT and IVUS were able to clearly delineate the presence of severe stenosis of the second segment of the right coronary artery. On the other hand, the coronary angiography has been a "battered gold standard" for decades . Recently, cardiac CT has undergone rapid advancements in technological resolution; in fact, the multiple slice spiral version is able to minimize cardiac-motion artifacts, thus allowing for a correct interpretation of the cardiac vascular anatomy and coronary artery disease . According to several studies, the sensitivity and specificity of cardiac CT for revealing the presence of CAD range from 82% to 100% and from 78% to 98%, respectively .
IVUS is now a routine procedure in several cardiac catheterization laboratories and is especially used for assessing the severity and morphology of coronary artery lesions and for evaluating indeterminate narrowing of the left main coronary artery or the presence of atherosclerosis progression and/or regression during drug treatment trials .
Angiography is always considered to be the gold standard technique for assessing the severity of obstructive luminal narrowing , but in some circumstances, it fails to provide a correct interpretation of the lumen vessel stenosis. In fact, some in vivo and post-mortem human studies have revealed that angiographically normal coronary lesions may have atherosclerosis [3, 6–9]. A possible explanation for this is that the presence of diffuse atherosclerosis may induce a remodelling of coronary arteries, thus making it difficult to detect normal reference segments . Furthermore, in the early phases of atherosclerosis, arterial compensatory enlargement may mask the presence of a plaque in the coronary artery lumen .
Consequently, other imaging techniques for diagnosing CAD may be necessary.
We aim to emphasize the role that IVUS plays in providing an excellent quantitative measurement of the atherosclerotic plaque and important qualitative information on its composition. Cardiac CT may also give an overall view of coronary atherosclerosis . However, some issues limit the use of IVUS for routine evaluation such as its invasiveness, the related increased risk, the additional time required, and high costs. Although cardiac CT is non-invasive, it cannot be used in patients with significant respiratory or renal failure or a major allergy to contrast material; in addition, cardiac CT is a technique that requires considerable training and is still operator-dependent .
In our case, although coronary angiography showed moderate stenosis of the second segment of the right coronary artery, the effort angina experienced by our patient and the presence of a severe stenosis on cardiac CT led us to carry out an IVUS study that allowed us to establish the correct diagnosis.
Unfortunately, our patient from 2004 to present had a total radiation exposure estimated near 120 milliSievert (mSv), a dose that several authors [13–16] consider to raise the cancer risk; according to the conclusions of BEIR VII Phase 2, the linear no-threshold relationship should be used for assessing the detrimental effects of these doses . However, based on the fact that incidence of cancer varies widely depending on age and sex  (our patient was an adult male) and that the potential benefit to our patient was greater than the long term risk of cancer, we decided to perform the cardiovascular interventional procedures. Because of its good sensitivity in detecting atherosclerosis in angiographically normal reference segments, IVUS may be a valid and helpful method for completing the diagnosis.
In our case, IVUS has also been very useful for assessing the extent of stent deployment and for determining the minimum luminal diameter within the stent. However, IVUS is an invasive procedure with the potential risks of vessel damage and acute thrombogenic vessel occlusion and should only be used for selected cases.
Therefore, we believe, in accordance with other authors , that IVUS is useful in the catheterization laboratory when angiography alone cannot clarify the coronary anatomy.
Written informed consent was obtained from the patient for publication of this case report and any accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal
List of abbreviations
bare metal stent
coronary artery disease
drug eluting stent
left anterior descending coronary artery
lumen area stenosis
minimal lumen area
percutaneous transluminal coronary angioplasty.
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