Coronary artery calcification on computed tomography

Abstract

Sir—Adrian Dixon and Richard Coulden,1Dixon AK Coulden RA Coronary artery calcification on computed tomography.Lancet. 1997; 350: 1265Summary Full Text Full Text PDF PubMed Scopus (9) Google Scholar in reviewing the evidence that coronary arterial calcification can be reliably detected without the need for expensive ultrafast electron-beam CT, find that thoracic-CT protocol examinations using more mundane and accessible equipment can frequently detect such calcification. With the prevalence of coronary disease in the UK, a reliable and accessible screening tool for coronary atherosclerosis would be invaluable. The use of coronary calcification in this regard is predicated on the assumption that radiologically detectable calcification is part of a complex atheromatous plaque, and that the sorts of complex, often ulcerated, atheromatous lesions that give rise to cardiac morbid events can be relied upon to be calcified, and hence detectable. Unfortunately, there are difficulties in these assumptions. First, although coronary calcification is indeed much more common in patients with obstructive coronary disease, it is also seen in many apparently healthy individuals,1Dixon AK Coulden RA Coronary artery calcification on computed tomography.Lancet. 1997; 350: 1265Summary Full Text Full Text PDF PubMed Scopus (9) Google Scholar and the correlation between the calcification score and the severity of atheroma is poor.2Thompson GR Forbat S Underwood RS Electron-beam CT scanning for the detection of coronary calcification and prediction of coronary heart disease.Q J Med. 1996; 89: 565-570Crossref Scopus (10) Google Scholar Second, in patients with renal disease, because of their well-known problems with calcium-phosphate homoeostasis, vascular wall calcification is very frequent, increasing with age, systolic blood pressure, and other biochemical indices;3Goldsmith DJA Covic A Sambrook P Ackrill P Vascular calcification in long-term haemodialysis patients in a single unit: a retrospective analysis.Nephron. 1997; 77: 37-43Crossref PubMed Scopus (205) Google Scholar here, calcification is circumferential and medial, not asymmetrical and intimal, and only rarely is it associated with occlusive atheromatous disease. Cardiac calcification (coronary arteries, valves, myocardium, pericardium) is also much more frequent in renal disease,4Braun J Oldendorf M Moshage W Heidler R Zeitler E Luft FC Electron beam computed tomography in the evaluation of cardiac calcification in chronic dialysis patients.Am J Kid Diseases. 1996; 27: 394-401Summary Full Text PDF PubMed Scopus (731) Google Scholar but in this clinical context the link between coronary calcification and presence and severity of coronary atherosclerosis is even weaker.5Utsunomiya M Angiographic study of stenosis and calcification of coronary vessels in long-term dialysis patients: examination of risk factors for coronary calcification.Nippon Jinzo Gakkai Shi. 1996; 38: 155-165PubMed Google Scholar There is one finding of greater promise—that the absence of any coronary calcification makes significant atheromatous disease very unlikely. Thus, false-negative results are uncommon with CT calcification-detection screening approach. Because of the low specificity, however, large numbers of patients would be investigated in some way after the detection of coronary calcification without important further pathological change being found in many. Vessel calcification is a feature of ageing, diabetes, and renal disease. Atherosclerosis is more common, but of course not universal, in each of these settings. I find the dogmatic assertion that CT detection of cardiac calcification could be of widespread use as a screening tool for coronary atheromatous disease too optimistic on present evidence. One should also not forget the radiation dosage involved if the procedure is to be repeated. Coronary artery calcification on computed tomographyAuthor's reply Full-Text PDF