The results of the BEST (Randomised comparison of coronary artery bypass surgery and everolimus-eluting stent implantation in the treatment of patients with multivessel coronary artery disease) study indicate that the long-term rate (4.6 years) of major adverse cardiac events is significantly lower in patients with multivessel disease undergoing coronary bypass grafting (CABG) than those undergoing percutaneous coronary intervention (PCI) with an everolimus-eluting stent. However, a registry study has indicated that there is no difference in mortality rates between PCI with everolimus-eluting stents and CABG
Writing in The New England Journal of Medicine, Seung-Jung Park (Asan Medical Center, University of Ulsan, Seoul, South Korea) and others state that previous studies have shown that CABG is associated with better outcomes than PCI in multivessel disease but add that these studies “may have been limited by their use of first-generation drug-eluting stents”. Therefore, the aim of the BEST study—which Park presented at the 2015 American College of Cardiology Annual Scientific Session (14–16 March, San Diego, USA)—was to compare outcomes with CABG in patients with multivessel disease with those of PCI with an everolimus-eluting stent (ie. a second-generation stent).
In the open-label study, 438 patients with multivessel disease were randomly assigned to the PCI arm (413 of whom actually received PCI) and 442 were randomly assigned to the CABG arm (382 of whom actually received CABG). The primary endpoint was a composite of death, myocardial infarction, or target vessel revascularisation. Major second endpoints included a composite of death, myocardial infarction, or stroke and a composite of death, myocardial infarction, stroke, or any repeat revascularisation.
At two years of follow-up, there were no significant differences in the rate of the primary endpoint between groups: 11% for PCI vs. 7.9% for CABG: p=0.32 for non-inferiority). There were also no significant differences in the as-treated analysis (11.2% vs. 7.5%, respectively; p=0.44). However at the long-term follow-up point (4.6 years), PCI was associated with a significantly higher rate of death, myocardial infarction, or target vessel revascularisation: 15.3% vs. 10.6% for CABG (p=0.04). Again, the findings of the as-treated analysis were similar to the intent-to-treat analysis (15.5% vs. 10%, respectively; p=0.02).
PCI was also associated with a significantly higher rate of death, myocardial infarction, stroke, and repeat revascularisation at the long-term follow-up point—19.9% vs. 13.3% for CABG (p=0.01). According to Park et al, this increase can be “attributed largely to the preponderance of events of any repeat revascularisation in the PCI group” (11% vs. 5.4% for CABG; p=0.0003). They add that there were no significant differences in the composite rate of death, myocardial infarction or stroke between groups—11.9% for PCI vs. 9.5% for CABG; p=0.26).
However while there was not a significant difference the rate of myocardial infarction between groups, the rate of spontaneous myocardial infarction was significantly higher in patients who underwent PCI (4.3% vs. 1.6% for CABG; p=0.02). Park et al comment: “In the landmark analysis of events that occurred more than 30 days after randomisation, there were more patients with myocardial infarction in the PCI group than in the CABG group (3.5% vs. 0.7%, respectively; p=0.004).
Speaking at the ACC, Park said: “Based on our data, CABG is still the preferred option for multivessel disease. We had thought that previous trials may have been limited by their use of first-generation drug-eluting stents, but the results show CABG still leads to better outcomes.”
Registry study shows no difference in mortality between CABG and PCI
An observational registry study, which was also published in The New England Journal of Medicine, has indicated there are no significant differences in the rate of all-cause mortality—at a mean follow-up of 2.9 years—between patients with multivessel disease undergoing PCI with an everolimus-eluting stent and those undergoing CABG.
In their study, Sripal Bangalore (New York University School of Medicine, New York, USA) and others compared data (using propensity matched scoring) for 9,223 patients with multivessel disease who underwent PCI with an everolimus-eluting stent with 9,223 patients with multivessel disease who underwent CABG. The primary outcome was all-cause mortality.
The immediate post-procedure follow-up (in-hospital or ≤30 days after the index procedure), PCI was associated with a significantly lower risk of death than was CABG (0.6% vs. 1.1%; p<0.001) and was also associated with a lower risk of stroke (0.11 vs. 0.29; p<0.001). At 2.9 years follow-up, the risk of death was similar between groups: 3.1% for PCI vs. 2.9% per year for CABG; p=0.50). In the BEST study, Park et al also found that there were no significant differences in mortality between PCI and CABG. They note that the increase in repeat revascularisation and spontaneous myocardial infarction they observed in the PCI arm did not seem to “translate into an overall increase in mortality”, but comment: “The power to detect a difference in mortality was limited; longer-term follow-up may help to determine whether these findings are durable.”
Similar to Park et al, Bangalore et al found that PCI was associated with a significantly higher risk of repeat revascularisation (7.2% vs. 3.1% per year for CABG; p<0.001) and a significantly higher risk of first myocardial infarction (1.9% vs. 1.1% per year, respectively, p<0.001) that was “driven by a higher risk of spontaneous myocardial infarction”. However, the use of complete PCI seemed to lessen these risks. The authors report that patients who underwent complete PCI did not have a significantly higher risk of first myocardial infarction than those who underwent CABG, and the difference in risk of repeat revascularisation between PCI and CABG was “less pronounced” in those who underwent complete PCI (although CABG was still more favourable).
In their conclusion, Bangalore et al state: “The choice between CABG and PCI with everolimus-eluting stents may depend on whether complete revascularisation can be achieved with PCI. If the answer is yes, the choice between PCI and CABG should be made on the basis of weighing the short-term risk of death and stroke with CABG against the long-term risk of repeat revascularisation with PCI.” However, they add that if complete revascularisation is not possible, their data “suggest that such patients do better with CABG.”