The Stent or Surgery (SOS) trial suggests that many patients with coronary artery disease (CAD) do better with bypass surgery than with stents.
SOS enrolled more than 900 patients with mutivessel coronary artery disease and randomized those patients to have either coronary artery bypass grafting (CABG) or stents. The study was originally published in 2002, and at that time, the surgery patients were reported to have significantly improved their 2-year survival compared with stent patients. A more updatereported on six years of follow-up data, shows a persistent survival benefit in CABG patients (93.2% in CABG patients vs. 89.1% in stent patients).
Critics of the SOS trial point out that other randomized trials have not shown a significant survival benefit in CABG patients compared with stent patients (though most of these studies have shown at least a trend in this direction) and that trials, such as SOS, were conducted with older technology, using bare metal stents instead of the newer drug-eluting stents (DES). Cardiology experts urge caution in interpreting the results of SOS and suggest waiting for the results of randomized trials, which are now being conducted, comparing CABG to DES.
One of the inherent problems with clinical trials in a rapidly advancing field, such as cardiology, is that by the time a study is concluded, technology will often have made the techniques used in the trial obsolete. In the case of SOS, both CABG surgery and stent technology have significantly advanced since the trial was designed and conducted. So cardiologists have a point when they urge caution in interpreting the results.
There are two reasons, though, that patients facing treatment for multiple coronary artery blockages may want to be aware of the SOS trial and of similar trials comparing stenting with CABG.
First, it is worth noting that as successive randomized trials have been conducted over the years comparing CABG with the latest catheter-based techniques (first angioplasty, then bare metal stents) in patients with multiple coronary artery blockages, the patients randomized to CABG therapy have consistently tended to do better. The results of the SOS trial are fully consistent with this trend.
Second, randomized trials comparing bare metal stents with DES have failed to show any survival benefit with DES over the older stent technology. Taking this fact into consideration, it is not obvious that DES should be expected to do any better than bare metal stents when compared with CABG. The results of SOS, therefore, might not have been measurably different had DES been used instead of the older stents.
So while cardiologists are correct in saying that the results of SOS do not prove that CABG provides a better chance at long-term survival than DES, that's not the whole story.
Based on current evidence, it seems clear that cardiologists who march patients with multiple coronary artery blockages directly to therapy with DES may be doing their patients a disservice. They owe these patients a straightforward discussion on the option of CABG, a discussion that includes addressing the possibility (even the probability) that the patient's outcome may be equivalent or better with surgery.
And while they're at it, cardiologists shouldn't forget to mention a few other relevant facts about the treatment of coronary artery disease. For instance, many patients with coronary artery blockages probably do not need either stenting or CABG but can be expected to do just as well with drug therapy. This was demonstrated in the COURAGE trial, reported in 2007. Also, using a DES carries with it an obligation for prolonged therapy with Plavix, a blood thinner that is expensive and whose management can be challenging. (See the current thinking on the risks and benefits of DES here.)
Patients with coronary artery disease should expect their doctors to discuss all these issues with them in some detail before ushering them in to the catheterization lab for stent placement.
Booth J, Clayton T, Pepper J, et al. Randomized, controlled trial of coronary artery bypass surgery versus percutaneous coronary intervention in patients with multivessel coronary artery disease. Six-year follow-up from the Stent or Surgery Trial. Circulation 2008; DOI: 10.1161/CIRCULATIONAHA.107.739144.
Taggart DP. Coronary revascularization surgery is effective on clinical and economic grounds, but stenting does not seem to be cost effective. BMJ 2007; 334:593-594.