SYNTAX: Stent Thrombosis Has Greater Impact on Mortality Than Graft Occlusion

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In patients with left main or triple-vessel coronary artery disease, stent thrombosis after percutaneous coronary intervention (PCI) occurs with roughly the same frequency as graft occlusion following coronary artery bypass grafting (CABG). However, stent thrombosis is more likely to result in mortality in both the short and long term, according to 5-year results of the SYNTAX trial published online October 16, 2013, ahead of print in the Journal of the American College of Cardiology.

In the ‘all-comers’ SYNTAX (Synergy Between Percutaneous Coronary Intervention with Taxus and Cardiac Surgery) trial, 1,800 patients with left main or 3-vessel disease were randomized to PCI with a paclitaxel-eluting stent (Taxus Express, Boston Scientific, Natick, MA) or CABG. At 5-year follow-up, there was no difference in all-cause mortality or cerebrovascular accident (CVA) between PCI and CABG, but the CABG arm fared better in terms of cardiac mortality, MI, repeat revascularization, and MACCE.

For the current study, Patrick W. Serruys, MD, PhD, of Erasmus Medical Center (Rotterdam, The Netherlands), and colleagues analyzed the incidence and clinical outcomes of stent thrombosis and graft occlusion at 5 years using SYNTAX protocol definitions. Later, the Academic Research Consortium (ARC) definition of stent thrombosis was implemented and an ARC-like definition for graft occlusion was created for direct comparison.

Five-Year Results

Follow-up data were available for 871 patients (96.5%) from the PCI cohort and 805 patients (89.7%) in the CABG cohort.

Per protocol stent thrombosis was found in 47 patients (5.2%), most frequently in the left main (19%) and proximal coronary vasculature (51.4%). Per protocol graft occlusion occurred in 32 patients (3.6%), most commonly in the distal right coronary artery (42%).

No difference in rates of ARC definite stent thrombosis and ARC-like definite graft occlusion was observed at 5 years. Landmark analysis showed more ARC definite stent thrombosis within 30 days of the procedure, but rates were similar between 30 days and 5 years (table 1).

Table 1. Estimates of Protocol-Defined Stent Thrombosis and Graft Occlusion

 

Stent Thrombosis
(n = 47)

Graft Occlusion
(n = 32)

P Value

Five Years

6.6%

5.5%

0.39

0-30 Days

3.0%

1.0%

0.03

31 Days-5 Years

4.2%

4.5%

0.68


Despite the similar incidence of these events, cardiac death was reported in more than one-third of patients following ARC definite (35.4%) and ARC definite/probable stent thrombosis (41.3%). In contrast, ARC-like graft occlusion was associated with no cardiac mortality and ARC-like definite/probable graft occlusion with 12 cardiac deaths (23.1%).

In multivariable analyses, lack of postprocedural antiplatelet therapy was the strongest independent predictor of ARC early stent thrombosis (P < 0.001), while any baseline angiographically visible thrombus (P = 0.003) or trifurcation lesion (P = 0.048) were the strongest predictors of late or very late stent thrombosis. The lack of a left internal mammary artery was predictive of graft occlusion (P = 0.050).

The causes of death in this population are multifactorial, the authors observe. “Consequently, directly attributing [stent thrombosis] to mortality is difficult, although it is clear there was a strong causal link,” they add.

Taxus Out of Date

Jeffrey W. Moses, MD, of Columbia University Medical Center/Weill Cornell Medical Center (New York, NY), emphasized that the study looked at the Taxus stent, which has subsequently been shown to produce higher rates of both restenosis as well as subacute and late stent thrombosis than contemporary DES.

“There have been enough comparative studies looking at Taxus vs. other stents to show that Taxus is significantly inferior,” Dr. Moses told TCTMD in a telephone interview. “These studies were in much less complex patients and there are certainly indications from these studies that the more complex the patient, the more that difference emerges.”

Clinicians must rethink how relevant SYNTAX is to contemporary treatments, he said.

“The stent thrombosis early and late had a devastating impact, with two-thirds [of patients] having myocardial infarction or death,” Dr. Moses said. “If we improve on that, then you have to recalculate what the true outcomes are in contemporary treatments of multivessel disease, and I don’t think that SYNTAX is applicable to that.”


Source:
Farooq V, Serruys PW, Zhang Y, et al. Short and long term clinical impact of stent thrombosis and graft occlusion in the Synergy Between Percutaneous Coronary Intervention with Taxus and Cardiac Surgery Trial: The SYNTAX Trial at 5 years. J Am Coll Cardiol. 2013;Epub ahead of print.

 

 

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Disclosures
  • The SYNTAX trial was funded by Boston Scientific.
  • Dr. Serruys reports no relevant conflicts of interest.
  • Dr. Moses reports serving as a consultant for Boston Scientific.

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