Abstract
Recent randomized trials comparing coronary artery bypass surgery (CABG) versus drug eluting stents (DES) observed better survival, survival free of myocardial infarction (MI) and free from death, MI and stroke in patients with 3-vessel disease and diabetics if they were treated with DES. In the past, when we used bare metal stent (BMS) and meta-analysis of randomized trials with BMS and CABG, patients with 3-vessel disease and those with diabetes at 5 years of follow up had similar incidence of death, MI and stroke with CABG and BMS. The results reported recently by the SYNTAX and FREEDOM trials suggested a lack of clinical benefit with DES compared to BMS. The author in the article compared these recent results with the above meta-analysis and made an indirect comparison among DES, BMS and CABG. Reasons for these intriguing findings were discussed, and also a search for potential solutions was conducted.
1
Introduction
During the main session of Transcatheter Cardiovascular Therapeutics (TCT) 2003, when results from the RAVEL and SIRIUS trials had just been released, one of my colleagues suggested that the introduction of drug-eluting stents (DES) in clinical practice would drive the end of restenosis, the Achilles heel of percutaneous coronary interventions (PCI). This in turn would immediately be translated into the end of coronary artery bypass surgery (CABG) in the majority of patients with coronary artery disease (CAD). Zero percent of angiographic restenosis with DES in the first pivotal trial justified the great enthusiasm seen in the interventional cardiology community. Although at that moment only limited pre-clinical data were available, only a few people raised points of concern around the widespread use of these devices .
Over the last 10 years many randomized trials and registries comparing DES and bare metal stents (BMS) have shown superiority of DES to prevent restenosis and target lesion revascularization. Despite a high incidence of very late stent thrombosis with DES , a large network meta-analysis confirmed the safety and efficacy advantages of DES over BMS during PCI procedures. This year, long-term results from two randomized studies comparing DES versus CABG were reported . In both, surprisingly, a significant survival advantage with CABG was seen. Also, the benefit of CABG over DES was also present in subgroups traditionally defined in the past as good candidates for PCI.
In the SYNTAX trial , patients with three-vessel CAD and left main disease were randomized to DES implantation or CABG. Significant lower cardiac adverse events, including death, myocardial infarction (MI) and a composite of death, MI and cerebrovascular accident (CVA) were seen with CABG at 5 years of follow-up. Additionally, the rate of repeat revascularization procedures was significantly in favor of the surgical arm. The benefit in the subgroup of patients with three-vessel CAD was significantly in favor of CABG treatment, a finding which strengthens for the first time the indication of this strategy in a randomized trial. The main results of SYNTAX determined that in 80% of patients with three-vessel CAD, CABG provided better survival, a lower incidence of MI and repeat revascularization procedures than did DES implantation. In the pre-DES era, a meta-analysis from randomized trials comparing PCI to CABG showed that only diabetic and elderly patients had a survival advantage with CABG. In that analysis, extension of CAD was not a predictor of poor outcome with PCI.
This month, the largest trial comparing revascularization strategies in patients with diabetes mellitus was reported. Five years of follow-up results from FREEDOM revealed that death, MI and CVA, the primary end points of the study, were significantly lower with CABG compared to DES (26.6% vs. 18.7%, respectively; p < 0.005). All-cause death and MI were also significantly lower with CABG.
Interestingly, in both trials, such results were not present in the first years of follow-up, and the DES group of patients had a continuous loss of their initial benefit beyond the first year. If we search for randomized trials comparing BMS and CABG in patients with multi-vessel disease, indirect comparisons between BMS and DES can be made. Previously, a meta-analysis of 3051 patients, including in the randomized trials from ARTS, ERACI II, MASS II, and SoS , reported similar incidences of death, MI and CVA between BMS and CABG at 5 years of follow up, despite a threefold increased rate of new revascularization procedures with PCI.
If we compare the results of SYNTAX at 5 years in the subgroup of three-vessel CAD with the above meta-analysis , we can assume that all adverse events, including death, MI and CVA, are now worse with DES. As seen in the Table 1 , any cause of death was 8.5% with BMS and 14.6% with DES, translated into an increased risk of 42% of such an event (p < 0.001). The same finding was observed with the 10.6% rate of MI when treated with DES versus 6.6% from the old BMS data, again meaning a 38% increased risk of such an event with DES (p = 0.003). In fact, the composite of death, MI and CVA was significantly higher (22% vs. 14.2% in DES and BMS, respectively, p < 0.001, Table 1 ). Surprisingly, a similar rate of target vessel revascularization was observed in the DES and BMS arms (25% and 25.4%, respectively). We may argue that in the meta-analysis, patients with two-vessel CAD were also included; although , if we analyzed only those patients having three-vessel CAD, any cause of death with BMS or CABG were similar (10.2% vs. 9.5%, respectively p = 0.71). Again, we can compare these results with the SYNTAX-DES arm and results are still significant in favor of BMS; death: 14.6% in 546 patients treated with DES versus 10.2% in 548 patients treated with BMS, p = 0.034 .
| BMS ⁎ (n = 1518) | DES # (n = 546) | p value | CABG ⁎ (n = 1533) | CABG # (n = 549) | p value | |
|---|---|---|---|---|---|---|
| Death | 8.5 % | 14.6% | < 0.001 | 8.2% | 9.2% | 0.52 |
| MI | 6.6 % | 10.6% | 0.003 | 6.1% | 3.3% | 0.017 |
| CVA | 2.5% | 3.0% | 0.64 | 2.9% | 3.4% | 0.66 |
| Repeat/revascularization | 25.0% | 25.4% | 0.86 | 6.3% | 12.6% | < 0.001 |
| Death/MI/CVA | 14.2% | 22% | < 0.001 | 14.6% | 14.0% | 0.78 |
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