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Evidence-Based Practice: MIDCAB or MADCAB

Chatswood, NSW, Australia

"I respect no study, and deem no study good, which results in moneymaking".

– Seneca

Evidence-based medicine can be seen as working towards minimizing variations in practice by making available the best information of the outcomes of different treatments.¹

Increasingly, Government and other healthcare funding bodies are concentrating on the economic variabilities in the provision of competing surgical technologies sometimes independent, or even ignorant, of the different health outcomes.

In the field of cardiothoracic surgery, the precipitant rush to minimally invasive cardiac surgical techniques (MICS) has been at the expense of failure to assess efficacy, safety, long-term outcomes, proper cost comparisons and failure to admit that minimal access direct coronary artery bypass (MADCAB) does not necessarily imply minimally invasive direct coronary artery bypass (MIDCAB).

Whilst accepting that the "minimalist" procedures can be performed by a limited number of surgeons, whose published results demonstrate their capability, the question is not whether the procedure is possible, but whether it should be undertaken by the majority of surgeons.

Limited surgical access for congenital cardiac conditions and some aortic or mitral valve procedures confers cosmetic improvements in patients in whom this is a consideration (children and some females), but the surgical demands are higher and therefore potential risks greater. These incisions are not new, but the publicity has.

However, in the field of coronary artery surgery, there are two fundamental groups of techniques. Those involving the use of the extracorporeal circuit and those operating on the "beating" heart.

In terms of exposing the patients to the "harm" of the systemic immune response syndrome (SIRS) and other alleged deleterious concomitants of cardiopulmonary bypass (CPB), no benefit can be claimed from port-access systems which are used for CPB in association with MICS. These devices may in fact be more harmful in patients with aortic and major vascular disease. Open exposure of the heart and great vessels for cannulation and inspection of the coronary vessels in their entirety confers major safety benefits at the expense only of a larger sternal incision. This is of greater importance in the increasing group of older surgical patients. In addition, cannulation and exposure in the less sterile, less accessible groin poses certain theoretical disadvantages.

It has been said that cardioplegic myocardial preservation allows average surgeons operating on a still surgical field to achieve accuracy of suture placement and graft geometry with excellent results.

Minimal access procedures on the "beating" heart, even if stabilized or with pharmacologic bradycardia or arrest do not allow the same safety of careful suture placement in a bloodless field. One can only imagine that this translates to a less perfect anastomosis, even in the most dexterous hands.

Review of series of patients in whom MIDCAB procedures are currently performed suggests that they would be ideal low-risk patients for intervention or traditional "open" procedures.

An unhealthy sextet of promoters continues to market the unbridled proliferation of minimally invasive techniques as promising lesser physiologic trespass and therefore better outcomes:

1. The uninformed and gullible public readily accepts smaller incision size, reduced hospital stay, and worse still, lesser cost, as equating with lesser "invasion" and better surgical result.
   
2. Healthcare economists and providers, who are cost containment driven, fail to comprehend the lack of association between optimal health outcome and cost, and are easily attracted to, and will even attempt to enforce, procedures which lessen high-cost hospital stay and transfer costs to the patient's community.
   
3. Cardiologists are at major fault for failing to properly assess the "new technology" and appropriately offer it to patients. The decision for MIDCAB surgery is often initiated by the referring cardiologists, some of whom display blissful ignorance of any surgical technique deeper than the skin incision. It would not be defamatory to suggest that some cardiologists trivialize the role of their surgical colleagues in cardiac care and presume to direct the operative procedure performed by an unequal surgical partner. The patient then presents to the surgeon with the full expectation that a specific surgical technique will be employed. Surgeons should learn from the history of angioplasty. Its early widespread use, without controlled application, led to the delayed realization of its limited role.
   
4. Major culpability for excessive promotion of minimally invasive cardiac surgery rests with the device industry. A great proliferation of instrumentationhas, in many ways, led the profession to experimentation with the "keyhole" techniques. It is true that newer devices have contributed in major ways to advancing minimal access surgery, but have equally inappropriately encouraged adventurous surgeons to greater pursuits in the absence of proper controls and review.
   
5. Surgeons also shoulder responsibility for being infected by the enthusiasm for minimally invasive cardiac surgery. The cardiac surgical community is not free from self promotion by more competitive members who advertise a higher capability related only to performance of minimal access surgery. Poor early results, often glibly attributed to the "learning curve", are hard to justify in the light of established safe techniques.No craft group nor accrediting body has formalized training for minimally invasive techniques. Attendance at one of the many short courses on minimal access surgery, often sponsored by industry, is often assumed to confer competence.
   
6. Predictably, the media promotes minimal access surgery. Objective information is subjugated by the need for sensationalism, and the enthusiasm for leading-edge technology.
   

The suggestion that MIDCAB should be employed to retrieve patients from interventional cardiologists is to be deplored. Combined procedures involving MIDCAB and concomitant coronary angioplasty or stenting would appear to substantially increase cost and need critical controlled study.

In order to satisfy the ethical and economic validation for a widespread application of minimal access procedures by the general cardiothoracic surgical community, major initiatives are mandatory. Controlled trials comparing MIDCAB with traditional open procedures and with angioplasty/stenting are urgently needed. Proper training of surgeons and accreditation of competence, by licensing bodies, will be essential to establishing a credibility for MIDCAB to withstand the test of time. Not all surgeons will be able to demonstrate the necessary skill to achieve acceptable results. Moreover, outcome analysis of clinical results and costs will be essential for the evidence base to allow widespread use of MADCAB procedures.

Reference

1. Smallwood RA. The realities of evidence-based medicine. Asia Pacific Heart J 1997;2:121–4.

This Article Extract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Alan W Gale Permission Requests Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Gale, A. W Search for Related Content PubMed Articles by Gale, A. W