How We Treat Heart Disease Isn't Good Enough - The Huffington Post
Researchers followed nearly 700 patients who presented with a heart attack or a threatened heart attack. Each patient had an angiogram to identify the blockage that was causing the problem; the culprit blockage was then ballooned open (a procedure called angioplasty) and a small wire mesh device called a stent was inserted to keep the blockage from reoccurring. That's a typical angiogram procedure, but in this study, each patient also went on to be evaluated with a newer technology called "catheter-directed intravascular ultrasound." The idea was to use the more discerning eye of intravascular ultrasound to assess how many atherosclerotic blockages, a.k.a. "plaques," the angiogram may have missed.
It turns out that the standard angiogram misses a lot of plaques. In this study, conventional angiograms documented a total of about 1,800 of these blockages, whereas intravascular ultrasound found 3,100 -- despite the fact that ultrasound can't even "see" the last third of an artery the way an angiogram can. Not only did the angiogram miss a lot of blockages, but it often underestimated the severity of the blockages it did find. For example, angiograms found just 12 high-grade blockages; intravascular ultrasound found 283.
Over the following three years about 20 percent of the study patients returned to the hospital with more heart problems, and many of them had another angiogram to try to identify where the new blockage was. For about half of the returnees, the new problem was caused by the growth of a previously noted, but small (and therefore unstented) blockage. In the other half of cases, the chest pain occurred because a previously placed stent had closed off. That's a 50/50 split despite the fact that small unstented blockages outnumbered the larger stented blockages by more than two to one.
The researchers were also interested in whether there were any particular features on the initial ultrasound that could have predicted which blockages ended up causing problems in the follow up period. Coronary artery blockages aren't just a pile of cholesterol goo, stuck to the side of an artery. They are in essence a wound, fixed in place -- a mixture of different material and cell types going through cycles of healing and/or recurrent damage. But an angiogram can only document the severity of a blockage; it cannot peer inside this wound the way an ultrasound can.
Don't get me wrong: stents can save lives. In certain heart attack situations, angioplasty and stenting has dropped short-term mortality rates from 13 percent to 3-5 percent; in other situations, it can prevent "after-shock" heart attacks and readmissions for angina. But treating a heart attack in the here-and-now is different from preventing one in the future, which stents don't do very well. That's because, as this study showed, we're lousy at picking which blockages we should use them on, and also because stents don't always stay open: they can slowly scar shut, or quickly clot off. As a cardiologist colleague of mine says, "We've created a new disease -- the stent."
The conclusion to this latest research might be "Oops, the best test we have to evaluate our country's most lethal health problem isn't all that good." If the conventional angiogram is moving down the podium, will there be a new gold standard? Many believe it will be either CT or MRI angiograms -- like intravascular ultrasound, these allow us to more accurately view the atherosclerotic scars that define coronary artery disease. Because stress tests can only detect severe disease (blockages of 70 percent or more), CT or MRI angiograms are also increasingly being used as a much more definitive screening test that can find coronary disease much earlier in its development.
In the meantime, if it took an angiogram and a stent to push that elephant off your chest, be grateful but not falsely reassured: you have been treated for coronary artery disease but not cured of it. The 90 percent blockage the cardiologist ballooned and stented may now be 100 percent open, but you'll need to be on medication to keep that stent open. And as this latest research shows, it's very likely that there are remaining smaller blockages that the angiogram either underestimated in size or didn't see at all. These could loom large in your future unless you aggressively treat the risk factors -- smoking, high blood pressure, bad cholesterol etc. -- that caused them to sprout up in the first place. Whenever possible, choose a smoke alarm over a fire engine.
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