Wednesday, March 22, 2006

Coronary Artery Bypass Graft Surgery Part 2

This is part 2 on CABG. There is also part 1.

The role of the coronary angiogram

The angiogram discovery was an important step in the development of CABG. It gave the cardiologist and cardiac surgeons a good look, not only at the blockage, but also at the location of the blockage, the size of the affected artery, the area of supply of the artery, and the condition of the artery before and after the blockage. It also tells us the function of the heart with great accuracy. All these details are important in deciding on CABG, it’s success and it’s risk.

A word about the latest MSCT scans.

It used to be that a patient will see a cardiologist when he feels unwell (usually chest pains due to heart artery blockage), or as a result of checkups which showed that there is a lack of adequate heart circulation (functional testing, like stress ECG). Here the decision is more straight-forward. Nowadays, with all the new cardiac scan technology available and the very business-like marketing, a completely well individual, who had a scan done, could end up being told that he has blockages and that he requires immediate angioplasty or CABG. The fact of the matter is that there are very few blockages that are silent (not felt by the patient), that threatens life immediately. There have been no medical study to show that silent blockages, picked up incidentally by the latest scans, when treated with balloon angioplasty or CABG, has made any difference to the patient. In fact, there is a lot of evidence to show that many very healthy soldiers, killed in the Korean and Vietnam Wars, had very severe blockages in their heart arteries. This was discovered on autopsy done. Severe blockages, when they are silent, and not "functionally important" (no evidence of functional impairment), may be compatible with normal life. Often, these blockages are presented as if every blockage will cause death. This trend is very worrying as it may prompt medical practitioners to use the "scare of blockages" to convince patients to undergo unnecessary procedures with it’s attendant risk and cost, without documented evidence of benefit. In fact, to date, the accuracy of the new scans has not been proven. It tended to vary from institution to institution. What was quoted in the earlier article were average numbers. We are still learning how to use it.

Who then should receive CABG?

1. Anyone with chest pains, arising from the heart, and validated by some form of functional cardiac testing.
2. In those without symptoms, especially those in the high cardiac risk category (eg the diabetics, those with strong family history, smokers, hypertensives, etc), should undergo some form of functional testing, eg stress ECG, stress echo, stress radionuclide scans etc.
3. Those who have the above two pre-requisite, should undergo coronary angiogram.
4. Whether or not this patient should undergo balloon angioplasty with the drug-eluting stent, or CABG very much depends on a) the anatomy of the blockages (the cardiologist preference), b) the resources of the patient and c) the patient preference. This decision will require a thorough discussion of the pros and cons of balloon angioplasty or CABG.

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