Saturday, November 29, 2008


The latest issue of New England Journal of Medicine, carried an article by Dr Miller of the results of CorE64, which was announced earlier at the 2007 Annual Scientific meeting of the American Heart Association. You may remember that the CorE64 study involved 291 patients, aged greater than 40 years, and who were due for a coronary angiogram, who also underwent the 64MSCT prior to the invasive coronary angiogram. The aim of the study was obviously to see how good 64MSCT is and compare it with the gold standard invasive coronary angiogram. The study was sponsored by Toshiba, and headed by Dr Julie Miller of John Hopkins, Baltimore. The results we know well. Just to summarise, the overall sensitivity was 85%, specificity 90%, positive predictive value 91%, and negative predictive value 83%.
This study is important because it is the first large scale, multi-center study, involving four continents ( N,America, S.America, Europe and Asia-including Singapore ). The previous study have all been single center, with their inherent bias.
I have always maintain that the 64MSCT is a useful diagnostic tool with some niche uses, but not good as a screening tool for CAD ( as we see it being used in Malaysia ). With a positive predictive value of 91% and a negative predictive value of 83%, this non-invasive angiogram could hardly be accurate. I have always thought ( based on the previous single center studies ) that the positive predictive value was nearer 93% and the negative predictive value was nearer 98%. If I am not mistaken, our own data by the Sarawak General Hospital, reflects that ( personal communication-Dr KH Sim ). But alas, it was not so, when we take scans from all from across the world ( or rather more real-live evidence ).
Of course, such poor results, couple with the obvious risk of radiation ( about 500 chest X-rays ), must make it a rather unacceptable mass screening tool. But if these scans are bought by rich businessmen ( including businessmen doctors ), and with extensive marketing and cost packaging, the common laymen may be hookwinked to think that this scans are the real thing that can diagnose CAD reliably. The pictures, taken in multi-colours are so seductive. Of course, the marketing team do not usually tell their clients that they are being severely irradiated.
I do use the CT scans for CAD diagnosis, but I like the Calcium scores ( which is best done by the EBCT scan, also less radiation ), in the context of the patient profile and symptoms, if any. Clinically, we would like the 64MSCT to be used as an ER screening tool for patients, in the risk group, who present with chest pains of indeterminate origin. We need a quick, screening check to exclude CAD. If the 64MSCT is negative, it is safe to send these patients home, and if the scans are positive, it may be better to observe them in hospital. This is particularly important in USA where hospital beds are expensive and crowded. In Malaysia, such is not the situation.
Even the investigators of CorE64 concedes that worldwide, the MSCT has been largely used, where the medical evidence does not support, and where business interest largely overshadow clinical interest. Basically, the 64MSCT is very much a business tool.
But then, is not the whole of medicine going that way.

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