Coronary and aortic calcification: is the relationship important?

Abstract

• Vol 9 • April 2007 328 Atherosclerosis is a systemic disease with varying presentations. It is important that the attending physician know the extent of the atherosclerotic disease in any patient suffering from or at risk of developing the disease – still the most common cause of death in the western world. Vascular calcifications are considered to be a marker for vascular atherosclerosis regardless of the imaging modality used: calcified aortic arch on chest X-ray, valvular calcifications on echocardiographic examinations, or calcified vertebral and carotid arteries on computed tomography scans during neurological assessment. Nephrologists are also well acquainted with tissue calcifications, which are very common in end-stage kidney disease and in patients on chronic dialysis. This phenomenon is caused by a disturbed mineral balance and high total calcium-phosphate product due to vigorous pharmacological intervention to prevent kidney-related bone disease. Data have shown that the extent of vascular calcification in these patients correlates with adverse clinical outcome [1]. On the vascular wall level, atherosclerotic plaque is one of the targets of excessive calcium accumulation, producing intimal calcification. Indeed, calcified vessels appear to be related to atherosclerotic plaques, and the amount of calcium seems to be associated with the degree of atherosclerotic burden. Two different pathologic processes related to aortic calcification have been defined. The first is connected to atherosclerosis and is associated with excessive calcium accumulation in the intimal plaque. The second is characterized by medial matrix remodeling, which is directed by different signaling molecules – morphogenes – that convert medial smooth muscle cells into osteogenic cells [1,2]. In this case the stiffness of the aorta impairs diastolic coronary flow and also increases left ventricle afterload, while the intimal process is associated with thrombus formation and embolization. Calcifications, possessing high contrast, are readily observed by any X-ray modality, especially CT scan. The first CT scans were unable to produce high quality imaging of the moving heart and aorta. But with the introduction in the late 1990s of high speed multi-slice spiral CT, intraaortic and intravascular calcium depositions could be detected, especially when contrast material was added. Fueled by technological improvements, extensive research has been undertaken to clarify the accuracy and clinical relevance of vascular calcifications, and especially, to determine outcome and improve risk assessment and prevention. The report by Eisen and colleagues [3], published in this issue of IMAJ, is yet another important step forward. In their study the authors evaluated patients with proven coronary disease and those who had had a non-invasive test suggesting the presence of coronary disease. All patients underwent double – helical spiral CT – at that time the state-of-the-art modality. Patients were assessed for both coronary and aortic calcification. They found that 91% of this high risk population had coronary calcification (392 of 432), and of these patients 70% also had aortic calcification, indicating diffuse atherosclerosis. As in a similar published work, both aortic and coronary calcifications were closely linked to older age, there were more calcium deposits in the descending than in the ascending aorta, and there was a strong association between the extent of coronary and aortic calcifications. This direct inter-relation between these two processes observed here supports the notion that aortic and coronary calcifications are both expressions of systemic atherosclerosis [4,5]. This study proves the ability of double-helical non-gated spiral CT to detect aortic calcifications accurately, but the evaluation of different coronary segments which may be difficult with this modality was not addressed in their report. The prevalence of left anterior descending calcifications was significantly higher (86.8%) than in other vascular beds (left coronary artery 60%, right coronary artery 62%), which may reflect the limitation of this non-gated modality to accurately evaluate some coronary branches. The main potential advantage of CT imaging over standard coronary angiography, apart from being non-invasive, is the potential ability of visualization of the coronary artery wall and not only the artery lumen. Image quality depends on device resolution, heart rate and rhythm, and the ability to hold breath. Since the time Eisen et al. recruited their patients, CT scans have developed considerably and today the cutting-edge devices in the field are capable of 64 slices per rotation [6]. These systems enable high quality true non-invasive coronary angiography. Recent publications indicate that these devices yield a very high negative predictive value for coronary disease (97–100%), rather good sensitivity and specificity (75–95%) and a generally more modest positive predictive value (68–91%) [6-11]. High speed CT permits more detailed morphologic images of the coronary tree within a single short breath-hold duration, overcoming motion artifacts. [6]. Major current limitations include artifacts caused by severe calcifications, the presence of stents, and operation stitches after bypass surgery, especially in older and diabetic patients [6]. Musto et al. [12] assessed the coronary tree in Coronary and Aortic Calcification: Is the Relationship Important?

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@article{Litovchik2007CoronaryAA, title={Coronary and aortic calcification: is the relationship important?}, author={Ilya Litovchik and Ricardo Krakover and Alex Blatt and Zvi Vered}, journal={The Israel Medical Association journal : IMAJ}, year={2007}, volume={9 4}, pages={328-30} }