In general, unless a person with CAD is having one of the acute coronary syndromes (ACS, that is, unstable angina or myocardial infarction), the use of stents or bypass surgery does not seem any better than medical therapy alone in improving the risk of myocardial infarction or death. However, doctors have known for a number of years that in the minority of patients who have severe CAD -- those who have either significant blockage in their left main coronary artery, or who have significant blockages in three other major coronary arteries (the right, left anterior descending and left circumflex arteries) -- survival can be improved with bypass surgery. Indeed, these are the only patients with "stable" CAD (that is, CAD which is not currently causing ACS) who pretty clearly do better with treatment that is more aggressive than drugs alone.
Accordingly, these cases of left main or triple-vessel CAD have remained something of a "last stand" for the cardiac surgeons -- these patients are nearly the only ones the cardiologists still feel obligated to refer for bypass surgery. And, as one might expect, the cardiologists have been chafing at the bit to produce clinical trials to show that stents are as good as bypass surgery even in these patients.
Their latest attempt to do so was the SYNTAX trial. This trial randomized 1,800 patients with severe CAD to either bypass surgery or drug-eluting stents, and followed them for 12 months after their procedures. SYNTAX was designed as a "non-inferiority" trial, that is, it was designed to demonstrate that stenting does not produce results significantly inferior to bypass surgery in these patients. The endpoint was a composite of death, stroke, myocardial infarction, and the need for repeat revascularization.
As it turned out, the SYNTAX study was negative. Stenting did NOT prove to be "non-inferior" to bypass surgery by the criteria laid out (that is, patients receiving stents had nearly 8% more of the bad endpoint events than patients having bypass surgery).
In response to these results, prominent cardiologists (including investigators participating in the SYNTAX trial) have been quick to point out that not all the "endpoint events" in this trial were of equal import, and that, for instance, patients randomized to stents had fewer strokes than patients randomized to surgery. And for that reason alone at least some patients with severe CAD ought to be considered for stenting (despite the overall results of the trial). To this end, the SYNTAX investigators are working to develop some sort of a "SYNTAX score" that will help doctors determine which individuals with severe CAD might do better with stenting.
The bottom line is that for people who have severe triple-vessel CAD or significant blockage in their left main coronary artery, bypass surgery still ought to be considered the primary mode of therapy. While there is no doubt many who would do well with stents, the results of the SYNTAX trial (being negative) should not to catalyze a major shift away from surgery and toward stenting in these patients.
Source:
Serruys P, Morice MC, Kappetein P, et al. Percutaneous coronary intervention versus coronary-artery bypass grafting for severe coronary artery disease. N Engl J Med 2009; 360:961-972.
