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SYNTAX Trial – Is CABG Underused?

The CFA Staff

We were recently discussing our years in the field of cardiovascular medicine and one of my colleagues vividly remembered the day our hospital performed its first percutaneous transluminal coronary angioplasty (PTCA) more than 30 years ago. 


 Our cardiovascular program was very early adopting the technology which required the hospital to send two of its best soon-to-be “interventional” cardiologists to Switzerland to learn the procedure directly from Dr. Andreas Gruentzig himself.  A new day dawned and the development and inevitable ascent of percutaneous coronary intervention (PCI) began.  With the rapid dissemination of this new technology, and the eventual addition of coronary drug-eluting stent technology, cardiologists had a new, clinically effective and cost effective tool that obviated at least some patients from having to undergo coronary artery bypass graft (CABG) surgery.  As it turned out, a lot of patients have avoided CABG since then!  According to the National Center for Health Statistics, PCI increased from about 561,000 patients in 2000 to about 1,313,000 patients in 2006 (up 134%).  CABG began its concomitant decline in volume from a high of about 607,000 patients in 2000 to a low of about 448,000 patients in 2006 (down 26%).  Not-so-gradually, a less-invasive, less expensive and safer procedure was able to eliminate a large number of more costly surgical procedures with considerably higher risks and recovery implications.  A good thing, right?

Maybe not.  The SYNTAX Trial (Synergy between Percutaneous Coronary Intervention with Taxus and Cardiac Surgery) the first large trial to compare stenting and CABG directly, first reported in early 2009, has continued to stir the controversy.  The trial randomized 1,800 patients (in Europe and the U.S.) with severe CAD to either CABG or drug-eluting stents, and followed them for twelve months thereafter.  On September 12, 2010 in Geneva, additional results were reported.  The researchers conclude that tens or even hundreds of thousands of Americans are having coronary artery angioplasty and stenting every year when they should be having CABG, and the result is an extra 5,000 or more deaths annually.  The trial randomized patients with severe CAD -- triple-vessel or left main disease.  This group has remained nearly the only subset of patients that cardiologists feel compelled to refer for CABG surgery.  It has been suggested that cardiologists have long been desirous of trial results that would show that stents are just as good as CABG even in these patients.


SYNTAX seems to prove otherwise. Three years after the procedure, those that received a stent procedure were 28% more likely to suffer a major event such as a heart attack or stroke, and 46% more likely to require a repeat revascularization.  They were also 22% more likely to have a mortal event.  It seems that, for the most severe disease, surgery has a real patient advantage.   For patients with mild disease, the two procedures offer equivalent results.  But the differences were much more dramatic for patients with more severe CAD.  Approximately 50% of all patients undergoing angioplasty in the U.S. have more severe disease.  Hence, the researchers conclusion that CABG is underutilized for patients in this category.


While surgeons have touted these results, some cardiologists continue to believe that some patients with severe CAD should still be considered candidates for stenting despite the results of the trial.  They argue that some of the “endpoint events” in the study, such as the rate of stroke (lower in stents than in CABG) are more important than others and work in coronary stenting’s favor.  To this end, the SYNTAX investigators are working to develop a “SYNTAX score” that would help physicians determine which patients would benefit the most from which procedure.  It seems inevitable that additional clarification will be produced; guidelines, protocols (and perhaps even governmental and/or insurance company dictates) will be produced to reflect the SYNTAX conclusion.  Cardiac surgeons may be happy, but how far will these results go in settling this issue with cardiologists and their patients (let’s not forget the need for a well informed patient in all this), and how will this impact CABG volumes over the next few years?  Despite SYNTAX, the struggle between competing procedures and competing specialists will surely continue.  Well designed research should clarify and enlighten.  Unfortunately, no matter how good the research and compelling the findings, sometimes enlightenment is often a difficult end point to achieve.


CFA invites your thoughts and comments.

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