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Where Those Cardiology Guidelines Come From, Part II

Posted on March 5, 2009
Filed Under Cardiology Topics, Guidelines, Abuse of |

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In his last post, DrRich agreed with critics who point out that cardiologists frequently promulgate their own sets of clinical guidelines which, while they may or may not be good for patients, inevitably further the interests of the cardiologists themselves. While offering up these obviously self-serving guidelines to the world, most cardiologists sincerely believe (DrRich asserts) that they are acting solely in the best interests of their patients.

DrRich will now attempt to finish answering the question he raised in that post - How does such a thing happen? How do cardiologists (or any other well-educated, intelligent individuals) get to the point where they are able to act primarily in their own best interests, while insisting to everyone - even to themselves - that they are actually acting in the best interests of others?

In prior posts on this blog,  DrRich has given examples of cardiology guidelines which seem primarily to serve the interests of cardiologists. And as we have seen, the Journal of the American Medical Association recently published an article that analyzed the entire galaxy of cardiology guidelines developed over the past 25 years, which concluded that the large majority rely for their authority on expert opinion rather than on hard data.

But in our present attempt to discern from whence this particular species of clinical guideline arises, let us ignore for now the galaxy of already finished guidelines, and concentrate instead on the large, gaseous nebulae (formed from massive clouds of clinical data) which give birth to clinical guidelines. Perhaps, if our powers of observation are keen enough, we can perceive a new cardiology guideline actually taking shape, and from that perhaps we can answer our question.

To this end DrRich calls his readers’ attention to the SYNTAX trial, whose results were published on February 19 in the New England Journal of Medicine. This trial randomized 1800 patients with severe coronary artery disease (i.e., either significant blockage in the left main coronary artery, or severe triple-vessel disease) to therapy with either bypass surgery or drug-eluting stents (DES), and assessed their outcomes 12 months after their procedures.

DrRich has previously noted that in general, patients with stable CAD (i.e., those who are not currently having a heart attack or unstable angina) do just as well with aggressive medical therapy as they do with invasive therapy. Well, people like the ones enrolled in SYNTAX are the exception to this rule. That is, patients with either of these two specific patterns of severe CAD have been shown to have improved survival if they receive bypass surgery. Indeed, these patients represent a virtual “last stand” for cardiac surgeons - they are nearly the only patients who cardiologists still feel obligated to refer for bypass surgery.  And, as one might expect, in their decades-long turf war with cardiac surgeons (a war which most cardiologists believe will eventually result in most cardiac surgeons gratefully accepting jobs as beer vendors at sporting events), cardiologists have chafed at this singular remaining obligation to refer.

Accordingly, SYNTAX, a study instigated by cardiologists and sponsored by Boston Scientific (a manufacturer of DES), was intended to show that with today’s technology, stenting yields outcomes that are not significantly inferior to bypass surgery in these patients. Specifically, that is, it was designed as a non-inferiority trial. This was certainly a modest goal - some might say too modest - but a positive result would enable cardiologists (the gatekeepers to all invasive CAD therapy) to simply keep these patients for themselves, just as they now do with all the other CAD patients. The SYNTAX trial asked the question, “Do I really have to refer these patients to the cardiac surgeon?” And the desired answer was, “No, it apparently is not statistically provable that you absolutely have to refer them, one supposes.” Judging from the study design, which was decided upon only after great deliberation, that answer would have been plenty good enough for the study designers.

But unfortunately, the SYNTAX study turned out to be negative. The endpoint of the study was a composite called MACCE (Major Adverse Cardiac and Cerebrovascular Events), and in this study included death, heart attack, stroke, and the need for more revascularization procedures. The bottom line is that in SYNTAX, the risk of MACCE turned out to be significantly higher for stenting than for bypass surgery. The study failed to meet even its modest goal.

But based on subsequent comments made in the general media and by cardiologists who participated in the SYNTAX trial, you would never know that. In fact, unless one reads public statements very carefully it would be easy to believe that SYNTAX was a major triumph for all fans of stenting, everywhere.

For instance, here’s an article from the New York Times (subsequently reproduced in hundreds of newspapers around the country) entitled, “Heart Stents Found As Effective As Bypass For Many Patients.”

And here’s the triumphant-sounding press release from Boston Scientific, where the negative overall results are buried deep within the 7th paragraph of a 9-paragraph statement (following all kinds of positive-sounding fluff), and are difficult to locate even if you are specifically looking for them.

And then here’s the more-than-triumphant press release from NorthShore University Health Systems, a leading site for the SYNTAX trial:

“At NorthShore, we experienced stunning outcomes [emphasis DrRich's] in patients whose only option would have previously been bypass surgery,” said Ted Feldman, M.D, F.S.C.A.I., Director of Cardiac Catheterization Laboratory, NorthShore University HealthSystem, and a lead investigator of the trial. “The data in this study will provide cardiologists with additional information as they determine treatment therapy for patients with complex CAD.”

Most remarkable of all, we have the spectacle of the lead author of the SYNTAX paper, Dr Patrick W Serruys, telling Heartwire, immediately after publication of the paper which he wrote, that the paper’s concluding sentence (”CABG as compared with PCI is associated with a lower rate of MACCE at one year among patients with three-vessel or left main coronary artery disease (or both) and should therefore remain the standard of care for such patients.”),  is just plain wrong.   He says this conclusion actually “is not the essence of the trial.” He only allowed that concluding sentence to appear, he now says, “because the New England Journal of Medicine wanted something more conservative.”  (Apparently, having the paper appear in a prestigious journal overrode the necessity of having the paper accurately reflect what the authors meant to say.)

In any case, Serruys insists (despite the conclusion expressed in his ink-not-yet-dry paper)  that many patients like the ones enrolled in the SYNTAX trial can safely be treated with stents, and indeed, he and his co-investigators are hard at work teasing apart the SYNTAX data in order to develop a so-called “SYNTAX score,” that will help cardiologists determine which patients they can treat themselves, without referring them for surgery. So indeed, despite the negative results, and despite the conclusion of their own paper, the SYNTAX trial is being spun by key trial participants themselves into a win (while not a complete victory, still a win).

What gives here? Why are cardiologists trumpeting the results of a clinical trial which, one would think, should engender disappointment, if not frank depression, among them?  Why is their enthusiasm about a negative trial so remarkable that major American media have been fully taken in? Are they simply that good at lying to us?

No. Nobody is that good at lying. The cardiologists deeply believe what they are telling us about the SYNTAX trial. As DrRich sees it, cardiologists have ingested the stenting kool-aid. They fully and completely believe, to the depths of their souls and notwithstanding the largely negative body of medical literature to the contrary, that stenting coronary artery blockages - in virtually any configuration and any clinical situation - saves lives. And if they haven’t been able to prove that yet, it’s just because of the vagaries of clinical research. One must not let spurious results from imperfect research block the Truth, lest one allow great harm to come to humanity.

This is why, as DrRich has described, cardiologists routinely cause their patients in whom they place stents for stable CAD to believe that the procedure is saving their lives, when all it’s doing is helping to relieve their chest discomfort.

And this is why, DrRich surmises, the SYNTAX investigators still insist that, buried within the vast body of clinical data the SYNTAX trial has generated, there simply MUST be something useful to cardiologists. Accordingly, the SYNTAX investigators have dived head-first into the proverbial room full of manure, enthusiastically digging for the pony who simply must be in there somewhere.

And indeed they have found their pony.

And here it is: While a straightforward analysis of the SYNTAX study (of the sort apparently insisted upon by the editors of the New England Journal) shows that bypass surgery wins hands down, if one delves a bit deeper into the data, one finds that one of the components of the MACCE endpoint - the incidence of stroke - was statistically higher among the patients randomized to bypass surgery. One also finds that the incidence of requiring revascularization was higher in the stent patients. So, taking these two interesting observations together, the investigators have concluded that patients receiving bypass surgery are trading a reduced need for subsequent revascularization for an increased risk of stroke - a bad trade indeed. Therefore, despite the overall results of the study, they have concluded that stents are better than bypass surgery for at least some patients. (And they promise to discover for us, during their current data-mining exercise from which a “SYNTAX score” will be invented, which patients those are.)  The cardiologists can now claim a partial but important victory in yet another battle in their long turf war with the cardiac surgeons.

And this - the reduced incidence of stroke seen in the stent patients - is the basis for the celebratory statements coming from SYNTAX investigators.

DrRich agrees that, as a general proposition, he would probably rather have an extra invasive cardiac procedure than a stroke, and suspects that most people would say the same thing. But before he buys what the cardiologists are selling here, he would like to make a few observations.

First, the results of the SYNTAX trial are the results. Stenting did not meet even its modest non-inferiority endpoint, and it failed to meet it by quite a lot. Once the pre-designated endpoint of a study is determined, any remaining observations that can be gleaned from the large amounts of data generated by the trial must be viewed as inconclusive, as merely hypothesis-generating. Such observations are not to be regarded as having sufficient statistical surety to vastly change medical practice, or figure into evidence-based guidelines. So, another clinical study would need to be conducted to prove the hypothesis that strokes are less frequent with stenting than with bypass surgery in patients like these.

Similarly, the breathlessly-awaited “SYNTAX score” - whose purpose, again, will be to select for cardiologists those patients they can just go ahead and stent rather than refer for bypass surgery - should not be incorporated into clinical practice. An exercise like this - in which investigators comb retrospectively through the clinical data, selecting out patients who had good results with stenting, then devising a group of characteristics that appears to differentiate them from those who did not - cannot possibly yield a validated, widely-applicable clinical tool. If they want to claim that their SYNTAX score is clinically useful, they will need to conduct another clinical trial to test that hypothesis.

Then (remarkably) there’s the largely ignored fact (reported by Dr Friedrich W Mohr, co-principle investigator of the trial), that among patients assigned to bypass surgery in the SYNTAX trial who experienced a stroke, nearly half of them had their strokes PRIOR TO SURGERY. What this means is that, in reality, the bypass surgery itself did not cause those strokes, a fact that ought to cause serious damage to the chief assertion of the stent-proponents. This fact alone turns their pony into a pig. The claim that stenting instead of surgery would have avoided these strokes is largely, if not entirely, spurious.

Proponents of stenting answer this last point by reminding us that the SYNTAX trial evaluated data on an intention-to-treat basis, so that once a patient agreed to randomization their data was tabulated, no matter whether or when they actually received the assigned therapy. So, counting those pre-operative strokes against bypass surgery is statistically appropriate.

And this is indeed correct. From a statistical analysis standpoint those strokes have to count against bypass surgery, and in computing the overall results of the trial, they did.  But what we’re engaging in here is a hypothesis-generating exercise - going over the data retrospectively to see if we can figure out what might have happened.   And the hypothesis we’re kicking around at the moment is that surgery led to significantly more strokes than stents.  And in this mode of analysis, it seems conclusive that the surgery could not have cause strokes which occurred before the patient ever went to the operating room.  And to argue otherwise is to openly display one’s bias, or piggishness, or desperation to validate one’s world view despite the obvious.  It is also most interesting that proponents of stenting insist on strict statistical purity when doing so strengthens their argument (even when, such as in a retrospective, hypothesis-generating type of analysis, it is inappropriate to do so), but are quite willing to ignore statistical purity (by treating as facts the various hypotheses they are busily inventing from the SYNTAX data) when doing so will support stenting in these patients.

And finally, the clinical choice as it has been starkly painted by many proponents of stenting - that the real trade-off in choosing between stenting and bypass surgery in these patients is the choice between the higher risk of stroke with surgery versus the higher risk of revascularization with stenting - is incomplete and misleading. Presenting the choice in this way clearly favors stenting, and this presentation entirely explains the positive press releases and subsequent media coverage of the SYNTAX trial. But this is not a valid comparison of risks for several reasons:

1) As noted above, the actual risk of stroke posed by performing bypass surgery in the SYNTAX trial has been substantially overstated for public consumption (by implying that the surgery caused those strokes, when half occurred prior to surgery).

2) Surgeons in the SYNTAX trial most often did not employ newer techniques now in routine use, such as off-pump surgery and LIMA grafts, both of which can substantially reduce the risk of stroke and other embolic phenomena.

3) Re-occlusion of the involved arteries (which occurred about equally in both groups in this study, and which spokespersons for SYNTAX seem to brush off as not such a big deal), is an entirely different phenomenon in patients who have received DES than it is in patients who have had bypass surgery.  After bypass surgery, re-occlusion tends to occur gradually, and the patient generally experiences recurrent symptoms of angina. But in DES, re-occlusion much more commonly occurs acutely, and catastrophically, leading rapidly to permanent cardiac damage and often, death.

4) Item # 3 might explain why the composite endpoint of “death, heart attack and stroke” was equal in both groups, even though stroke was significantly higher in the surgery group. That is, in order for the math to work out, the remaining dyad of “death and heart attack” necessarily must have been higher in the stent group.  As far as DrRich can tell, this point has never been discussed in public.

5) In order to avoid the catastrophic re-occlusions seen with DES, cardiologists now insist that their patients take long-term, even life-long, Plavix. As the purveyor of a patient-oriented website on heart disease, DrRich cannot tell you how many distressed and stented-up patients have written to him with the following lament:

“My doctor put in one of those drug coated stents and has me on Plavix. He says if I stop the Plavix I could die, and won’t let me stop it for any reason. But I need my gallbladder out because I keep having attacks, and the last one gave me blood poisoning. My surgeon says I need the surgery but he won’t do it unless I stop Plavix, and my cardiologist says no stopping the Plavix for any reason. What can I do? Can they just take these stents out so I can stop the Plavix?”

There is no easy answer to this, at least not that DrRich can find. The stent patient is left in the middle of a pissing match between surgeon and cardiologist. The fear of the cardiologist is that when one stops Plavix, there is a risk of sudden, catastrophic thrombosis of the coronary artery. But surgeons simply cannot operate safely on patients taking this drug. Few cardiologists seem to explain this to their patients before placing DES.

And more to the point at hand, none of the cardiologists spinning the SYNTAX trial are explaining to the public the implications of long-term Plavix. Even if their claims that stenting yields significantly fewer strokes turned out to be accurate, the choice here is clearly NOT a simple one between a higher risk of stroke on one hand, and a higher risk of needing “revascularization” (if they survive the re-occlusion, that is) on the other. There’s a lot more to think about than that, and cardiologists who imply otherwise are being either disengenuous, or delusional.

Summary:

To summarize the main point of these last two posts, cardiologists exist within their own world view on stenting. They deeply and completely believe that stents save lives, and they are out to prove it. This world view informs everything they do, in their attitude toward their patients (an attitude they successfully convey to patients who have received stents), in how they interpret objective clinical evidence, and in their formulation of clinical guidelines. (Several prominent cardiologists have already hinted that the SYNTAX trial will soon lead to more liberal guidelines regarding stenting patients with severe CAD.)

DrRich would like to close with one final observation, one he has already made, to wit: there’s nothing unusual about cardiologists. They are regular people, just like everybody else.

To DrRich this means that, as our new political leaders advance a system under which they will assess clinical evidence to determine what they should and should not pay for, they too - just like the cardiologists - will be applying their own world view to the interpretation of that data. Unlike the cardiologists they will not be interested in encouraging the use of any particular procedure. On the contrary, their own world view - which will be at least as deeply felt and all-encompassing as that of the cardiologists - is one in which too many greedy doctors are ruining the healthcare system by over-utilizing too much expensive technology. (Like all world views there is something to this one, and the recent actions of DrRich’s cardiology colleagues are doubtless adding force to it.)  But such bias on the part of the soon-to-be all-powerful governmental payers will quite predictably lead to new tricks of statistical legerdemain, tricks that, one fears, will render the kind of “cardiology logic” we’re seeing today a fond memory from a more innocent time.

Perhaps we should thank our cardiology friends for demonstrating the kind of results a hidden agenda can produce when highly educated individuals are engaging in purported scientific activity. The accurate interpretation of scientific data requires that there be no hidden agendas, otherwise the results will be predictably damaging.

And when it comes to healthcare, covert rationing is the most damaging hidden agenda of all. It is one against which neither scientific methods, nor ethical standards, nor the rules of civil society can prevail.

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