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EDITORIAL |
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Mid-Atlantic Heart Institute Lancaster General Hospital Lancaster, Pennsylvania, USA |
No man should test the depth of a river with both feet.– African Proverb
With the advent of minimally invasive and off-pump coronary artery bypass grafting (CABG), cardiac surgery has reached a "strategic inflexion point" at which alternate pathways offer both dangers and opportunities that may lead to increased success or dismal failure. Since the price of a cardiac surgeon's misjudgment is ultimately paid by the patient, at critical junctures it is vital to maintain our profession's tradition of vigorous discussion and debate about new technologies. Most of my comments will be about off-pump coronary artery bypass (OPCAB) because avoidance of the pump seems a worthwhile goal. In contrast, with current technology, the complexity and risk of port-access coronary bypass with the pump seem to outweigh the benefit of merely avoiding a sternotomy. This view may change as we improve port-access techniques but I know from personal experience that sternotomy incisions are not so bad. Furthermore, port-access CABG is done in relatively few centers compared with off-pump CABG.
When coronary bypass was first introduced, there were many loud voices of skepticism in the cardiology community asking for randomized trials before even one more patient had surgery, while the surgeons countered that CABG surgery should be disseminated widely without further delay.1,2 Why the more cautious attitude toward innovation now?3 The simple answer is that in 1967 to 1968 we had nothing else to offer coronary patients who were dying without surgery. Today, there is already a highly satisfactory surgical option for coronary patients.
Michael Mack4 has pointed out that we must not fall into the inertia of our past success and must grasp the opportunity to change. I agree, but would add that our success with conventional CABG is not irrelevant and has a strong bearing on the discussion. It is not as if the new techniques promise better long-term results due to more complete revascularization with more arterial conduits, higher graft patency rates, or better myocardial preservation. On the contrary, the conventional operation offers the gold standard for all those parameters that bear on long-term results, whereas minimally invasive techniques only strive to match that standard. Rather, these new approaches claim the advantage of smaller and more cosmetic incisions, avoidance of the pump's morbidity, shorter hospital stays and recovery, and hopefully, decreased costs. When a new technique only offers short-term benefits, it must first demonstrate that its long-term results are at least as good as the established technique. This important principle must not be overwhelmed by the fervent hope that these techniques will provide an alternative to interventional cardiology techniques and increase surgical volume with new cases that would otherwise have been managed by interventional cardiologists without surgery.
Of course there is always room for improvement but conventional coronary bypass has many characteristics that provide a benchmark for assessing any new technique. Modern coronary bypass surgery is offered to patients with diverse manifestations of advanced coronary disease by a vast cadre of highly experienced surgeons who perform operations that are safe, effective, durable, consistent, complete, versatile, and teachable, and that deliver long-term cost savings because of the low incidence of complications, follow-up catheterizations, and repeat revascularizations. The documented excellent outcomes with conventional coronary bypass are due to a number of critical components: uncompromised selection of the best sites for the anastomoses; ability to respond to unexpected circumstances such as intramyocardial vessels; use of properly chosen optimal conduits of exact length; avoidance of trauma to conduits and native vessels; optimal conditions for microvascular anastomoses; and complete multivessel revascularization.
Operations without the pump or through small incisions are prolonged and technically more challenging, and it may be difficult for some surgeons to achieve the kind of results they are accustomed to with a flaccid arrested bloodless heart. It is a paradox that the pioneers of minimally invasive techniques, many of whom are exceptional surgeons, now assure us that anyone can do it well. We must have data, preferably from controlled randomized trials, to confirm that the short-term benefits of off-pump and minimally invasive surgery do not come at the cost of incomplete revascularization or diminished graft patency due to the more difficult anastomoses, intraoperative trauma to conduits or coronary arteries, or selection of poor conduits or target vessels.
Although this field is advancing rapidly and there are reports of satisfactory early graft patency in selected patients at certain highly experienced minimally invasive direct coronary artery bypass (MIDCAB) centers, these reports only mention left internal mammary artery-to-left anterior descending coronary artery (LAD) grafts.5 We still have no data about the far more difficult anastomoses to branches of the circumflex and right coronary arteries, not to mention the high diagonal branches of the LAD. To say that "these early results are comparable to any published series on graft patency with conventional coronary bypass surgery," is to ignore the importance of any artery except the LAD.4
Although "hybrid revascularization" combined with angioplasty is an intriguing option for other arteries, and I have used it myself in highly selected and usually very elderly patients, coronary bypass became accepted as the preferred treatment for coronary disease only after multiple long-term studies demonstrated improved survival compared with medical management, and this improvement was demonstrated principally in patients who had complete revascularization. If we advocate incomplete revascularization, we undermine the entire clinical basis for the legitimacy of coronary bypass and we will once again have to defend its value. We have criticized cardiologists in the past for ignoring secondary lesions in their zeal to carry out so called culprit lesion angioplasty. Are we now to succumb to the same tunnel vision? We are told that the public demands these techniques. Yet this is the same public that spends vast sums of money on unproven alternative medicines. The public unwisely demands all kinds of new therapies and we must guide them without bias or self interest. Many alternative-medicine therapies work because people believe they will work, which illustrates the power of positive thinking. Yes, MIDCAB patients leave the hospital a bit sooner and return to full activity somewhat sooner than after conventional surgery but patients who have MIDCAB surgery are told in advance that they will recover quickly and this expectation has a powerful effect. Recall that for all patients the current rapid or "fast track" recoveries would have been considered impossible just a few years ago.6 One reason for their success is simply that patients expect a short stay and welcome rather than resist early discharge.
But let us accept for the sake of this discussion the assertion that the patency rates of OPCAB grafts to the LAD, in certain selected patients at particular centers, are acceptable and perhaps even comparable to patency rates reported for the millions of unselected patients who have had surgery with conventional techniques. Let us also agree that these current acceptable results and patency rates for OPCAB procedures are considerably better than those achieved only a short time ago, to a great extent because of the introduction of stabilizing devices but also because of the inevitable improvement that comes from increased experience with any new procedure, the so-called "learning curve". Even with all these assumptions, there are much broader implications to the fact that these results have improved so rapidly. Implications on the one hand for the patients who were operated upon too early in the evolution of these techniques and who had postoperative angiography that would not otherwise have been necessary, and then in many cases, reoperation because their grafts closed, and implications on the other hand for those fortunate patients who were not operated on during someone's learning curve but instead had successful complete revascularization by conventional techniques, although they may have had a few more postoperative injections of morphine and a week or two more before they could swing a golf club. These implications lead to the broader question: when in the course of any new operation's development is it appropriate to offer an evolving procedure to a patient? When a satisfactory operation already exists, we should be cautious about a new technology specifically because it evolves so rapidly. In other words, the very fact that improvement is occurring so rapidly makes it especially important that we are sure each and every patient is receiving the operation that at the moment is most likely to give that patient the best long-term result in the hands of the surgeon doing the operation. If we are unsure of the choice, then there is an obvious need for a randomized trial.
All surgeons surely agree that our therapeutic choices must be made only to further the patient's welfare and we must not embrace change merely for the sake of protecting our reputations, our influence, or, heaven forbid, our pocketbooks. We must always put the patient first.
References
This article has been cited by other articles:
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  L. I. Bonchek Off-pump coronary bypass: Is it for everyone? J. Thorac. Cardiovasc. Surg., September 1, 2002; 124(3): 431 - 434. [Full Text] [PDF]
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