Monday, July 24, 2006

Screening for Vulnerable Plaque

Acute coronary thrombosis (blood clot in heart arteries causing a heart attack), occurs as a result of plaque (cholesterol accumulation in heart artery) rupture or erosion. When the endothelial (membrane lining the artery wall) cracks as a result of stress on it, it exposes the inside layer of the heart artery to the flowing blood. This causes the flowing blood to clot on it, in an attempt to stop the bleed. The blood clot can obstruct the flowing blood in a passage already narrowed by the cholesterol accumulation. This obstruction causes a no-flow situation in the heart artery and the result is loss of blood supply to the heart muscles and so death of heart muscle, which is what we call a heart attack.

Researchers have been trying very hard to indentify the patients who have vulnerable plaque (plaque waiting to crack), and possible treatment, before the plaque can rupture, thereby preventing heart attack. This makes it sound so easy and strightforward. Far from it, obviously, because all patients are different.

Sometimes it is a vulnerable plaque, sometimes a vulnerable patient, sometimes a deadly combination. The search goes on. Perhaps I should have started by saying that all of us potentially have cholesterol plaques in our arteries. As long as they are stable and do not rupture, we are fine. Perhaps we may experience some chest pains every now and then, but no catastrophies.

In the search to differentiate a vulnerable plaque from a not so vulnerable plaque, researchers in USA have put their experence together in a supplement to the latest American Journal of Cardiology, promoting the idea that MSCT scanning of the plaque and measurement of carotid artery thickening in individuals with 2 or more coronary risk factors, like raised cholesterol, diabetes, metabolic syndrome, hypertension, those with family history, and cigaratte smoking, may help us to identify the vulnerable plaque. Well I suppose, if you are an expert in MSCT and your machine can define the plaque well enough to measure the different tissue density of the plaque, you can try and detect the vulnerable plaque.

My concern is that this report from AJC will be used as an excuse by those with MSCT machines out there, to market this new guidelines and pretend that after doing 200 scans, they are experts who can identify vulnerable plaques. Nothing is further from the truth. These American researchers have teams of cardiologist and technologist working with them, doing nothing else but MSCT and plaque density measurements, to arrive at this level of expertise. As we say jokingly sometimes, the machine is good and so is the technology, but the idiot behind the machine is what is important.

Tragically this is the era of commercialisation in medicine, the marketing department takes over, and all medicine is lost in an attempt to strenghthen the bottom line. In this regard, it is heartening to note that the government is preparing a Devices Act, to curb the rampent abuse of medical technology to make money. Perhaps it is too little too late, but maybe better late then never.

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