An article in a medical newsletter I regularly receive Not so Fast: How to Avoid Bias Toward Stents in Managing SIHD describes the unnecessary revascularization of coronary arteries in patients with many patients with SIHD (stable ischemic heart disease). The author of the piece is, of all things, an interventional cardiologist. She quotes several studies. One concluded that percutaneous coronary intervention (PCI) “did not reduce the risk of death, myocardial infarction, or other major cardiovascular events when added to optimal medical therapy” in patients with stable coronary disease.(NEJM 356:1503-1516, 2007). A second study (a meta-analysis) reached a similar conclusion: “Initial stent implantation for stable coronary artery disease (CAD) shows no evidence of benefit compared with initial medical therapy for prevention of death, nonfatal MI, unplanned revascularization, or angina.” Arch Intern Med 172:312-9, 2012
I’ve written about this subject before; nevertheless, I think some additional comments are worthwhile. It’s been obvious for decades that many revascularization procedures convey no benefit. To begin with, it’s up to those who devise a new and invasive therapy to show that it’s beneficial. With coronary revascularization the profession just assumed that opening clogged arteries had to be better than leaving them alone and offering medical management in its stead. This thinking ignored some basic cardiovascular physiology.
The heart is a rather simple organ, albeit a vital one. It’s purpose is to pump blood to all the body’s organs. So when someone is found to have obstructed coronary arteries the first question should be, but typically is not, is the heart functioning normally, ie, is cardiac output normal such that organ perfusion is normal? If it is, then what is the point of opening a clogged artery? In such an instance the heart is getting enough blood irrespective of the obstructed arteries.
Now, the issue of stable CAD. How do we know it’s stable? The only way is to have observed a patient with CAD for a prolonged time. CAD has to start some time or other. When it’s first diagnosed it can’t be termed stable. So either it’s treated by revascularization or it’s treated as if it were stable when the physician has no way of knowing its stability. There is another possibility. The patient may have had symptoms for a while and not sought medical assistance and still escaped catastrophe.
We’re back to cardiac function. That’s the key issue, not stability. If cardiac output is sufficient to normally perfuse all the body’s organs then medical treatment should suffice. The Coronary Artery Surgery Study , which has gone on for decades, has repeatedly shown that revascularization did not benefit patients with CAD whose ejection fractions (EF) were greater than 0.50. It also showed that if the EF was less than 0.30 the patient’s disease was too advanced to benefit from aggressive intervention. EF is easily measured with echocardiography and has no risk other than the patient falling off the table.
The cardiologists have gotten themselves stuck on a medical Möbius strip. When a patient first presents with new angina or other symptoms or signs of CAD he doesn’t have stable CAD and likely is subjected to coronary revascularization. If he somehow escapes such a procedure and develops stable CAD he may still get invasive therapy. As mentioned above, the physician should avoid the issue altogether by observing cardiac function. What’s abundantly clear is that many patients who undergo coronary revascularization don’t need it. How many? Difficult to say, but it could be more than half.