Burt came to me last week. He'd received a stent a few months earlier. He'd been feeling fine except for some fatigue. A nuclear stress test proved equivocal, with the question of an abnormal area of blood flow in the bottom (inferior wall) of the heart.
"The doctor said I had a 50% blockage. Even though it wasn't really severe, he said I'd be better off with a stent, just in case."
Just in case what? What justification could there be for implanting a stent "just in case"? (The artery that was stented did not correspond to the area of questionable poor blood flow on the nuclear stress test.)
Just in case of heart attack? If that's the case, what about the several 20 and 30% blockages Burt showed in other arteries? The cardiologist was apparently trying to prevent the plaque "rupture" that results in heart attack by covering it with a stent. Why stent just one when there were at least 7 other plaques with potential for rupture?
That's the problem. And that's why stents do not prevent heart attack (unless the stent is implanted in the midst of heart attack, when the rupturing plaque declares itself.) Of course, when no plaque is in the midst of rupturing, as with Burt, there's no way to predict which plaque will do so in future. Since only one plaque was stented, there is a 7 out of 8 chance (87.5%) that the wrong plaque was chosen. And that's assuming that there aren't plaques not detected by catheterization angiogram; there commonly are. The odds that the right plaque was chosen would be even lower.
In other words, stenting one blockage that is slightly more "severely blocked" in the hopes of preventing heart attack is folly. If it's not resulting in symptoms and blood flow is not clearly reduced, a stent can not be used to prevent plaque rupture. A stent is not a device to be used prophylactically. It is especially silly when an approach like ours is followed, since plague progession is a stoppable process.
Note: This issue is distinct from the one in which symptoms and/or an abnormal stress test show clearly reduced blood flow and flow is restored by implantation of a stent. While some controversies exist here, as well, a stent implanted under these circumstances may indeed provide some benefit.